Model Engine Maker
Supporting => My Workshop => Topic started by: zeeprogrammer on February 08, 2020, 09:24:11 PM
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I've been interested in CNC for a long long time and finally decided to take the plunge.
While everything I've done has had no need for CNC, there have been times where I've envisioned a part where CNC would be very useful if not required.
An example is making a set of identical bowling pins. Another would be engraving.
I won't go into all the reasons for the choices I've made in machine, software, etc. Here's some...
I wanted small machines that either were CNC capable or could easily be made CNC capable.
I've used Windows since the beginning.
I got hooked on Sherlines when they first came out (call it an old dream).
I still have my PM1030 lathe and PM25 mill and it looks like I'll be keeping them.
That means I have to re-arrange my shop which is part of the reason I'm doing this in "My Workshop".
This project will take a long time. There is so much to learn. I'll first start by playing with and learning about the machines prior to converting them to CNC.
The major elements of the project include:
1) A full workshop package from Sherline that includes their lathe and mill. I got the manual version and bought the CNC retro-fit kits separately. You can also buy CNC-ready machines. There's good arguments to go for CNC-ready but you have to install motors even if you intend to use the machines manually. I wasn't interested in their full CNC package. It includes a Linux based computer and seems to me to be outdated.
2) A CAD program. I have CubifyDesign which is fine for my purposes but will likely investigate Fusion360.
3) CamBam software for generating g-code. No particular reason other than it's very popular and has been around for years. A lot of support available.
4) Mach3 software to process the g-code and control motion. This is also very popular and has been around for years. (Note that it requires Windows.)
5) SmoothStepper Motion Controller. Also popular.
6) Gecko G540 stepper driver. Also popular.
I started out ordering quite a bit of Sherline stuff. Some of it I may not need once I convert to CNC.
Attached is a Bill of Materials spreadsheet.
A couple of pics of what I've collected.
1) 3 boxes from Sherline
2) Some CNC stuff (Smoothstepper, Gecko, Motors, and power supplies).
As always, criticisms, suggestions, examples of your own are most welcome.
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Some more pics of the goodies I got...
1) One of the boxes from Sherline was filled with a bunch of boxes. The ones to the right are the accessories etc. that was part of the workshop package. The ones to the left are the additional accessories I purchased.
2) These are the unassembled machines. The eagle-eyed amongst you will notice the mill's column is backwards. ::)
3) The machines lightly assembled. I will disassemble them for cleaning and oiling and then re-assemble and align.
4) This is the set of accessories that came with the workshop packaged.
5) This is the set of additional accessories I purchased.
6) This shows the CNC retro-fit kits.
Again, thanks to all of you who helped me in the Chatterbox thread.
It's 4:30 here. Close enough to 5:00 IF you know what I mean. :drinking-41:
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Christmas in February! :whoohoo: :cartwheel:
I'm looking forward to following your journey Zee. :popcorn: :popcorn: :popcorn:
Jim
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Zee:
"but you have to install motors even if you intend to use the machines manually"
Wellll... I got the zeroing dials, and put them on a little bit of 6.35mm rod (1/4 in old school) and on another CNC mill, milled faceplates that fit where the steppers go, with a 6.35mm hole in the middle so I can use them manually without the steppers in place. A bit of that label maker print with "----" stuck on provides a mark so I can match with the handle dials.
Do they work? Yes, but, with my lathe, with the stepper adapter in place, I can't easily slide the tailstock off. :???:
Like you, I think these little machines are great, and I'm glad Sherline are producing and designing more and more.
Keep going, and thanks for the updates.
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Thanks Jim.
Alex: Yeah, I forgot a couple of fellows on the other thread showed some ideas for manually moving the motors on a CNC-Ready machine. Thanks for the reminder.
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Zee,
Here's a link to the better Y Axis lock I was mentioning some time back: https://sherline.com/wp-content/uploads/2016/04/tip_028.pdf It works great and would be a great project to test out your new machines.
Here's a video about the same thing: https://www.youtube.com/watch?v=hFlbKQmm6Hw
Jim
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Zee,
Here's a link to the better Y Axis lock I was mentioning some time back: https://sherline.com/wp-content/uploads/2016/04/tip_028.pdf (https://sherline.com/wp-content/uploads/2016/04/tip_028.pdf) It works great and would be a great project to test out your new machines.
Here's a video about the same thing: [youtube1]https://www.youtube.com/watch?v=hFlbKQmm6Hw[/youtube1]
Jim
Seconded, I put one of those on my mill a while back, works great. Just have to remember to loosen it again when done with a position.
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Thanks!
You guys are going to get a lot of questions from me.
I (tried to) install the QCTP I got from LMS. I say 'tried' in the sense that I don't know if I got it right.
The instructions indicated I should use the short set screw and leave off the original base.
But that combination set the cutting tool too low regardless of adjustment.
I used the longer set screw and put the original base back in. Now I can adjust the cutting tool against the center line.
Only thing is...now the big nut on top that holds the QCTP to the table doesn't fully engage. There's about 2 threads (maybe 3) shy from the bolt to the top of the nut.
I feel like I'm asking for trouble.
But I just started playing. ;D So there are possibilities I haven't tried yet.
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Looks like a whole pile of fun there, Zee! ;D :popcorn:
I'm looking forward to following along with your learnings. I'm not ready to go CNC yet, but who knows, I may want to someday. And it's sure fun to watch and learn! :)
Kim
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The hieght of the holder on the qctp depends a lot on which tools you ate using. On mine I added a ali plate under the post to let me put another t nut out the side to prevent twisting with long boring bars. Had the side effect of raising the whole thing, which helped you issue too. Another quick fix is a bit of bar under the tool inside the holder. Too many combos of tool thicknesses and cutter tip positions to have aftermarket add-ons work everywhere.
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The hieght of the holder on the qctp depends a lot on which tools you ate using. On mine I added a ali plate under the post to let me put another t nut out the side to prevent twisting with long boring bars. Had the side effect of raising the whole thing, which helped you issue too. Another quick fix is a bit of bar under the tool inside the holder. Too many combos of tool thicknesses and cutter tip positions to have aftermarket add-ons work everywhere.
Zee..........here's an example of the plate Chris is talking about. My plate is for my A to Z tool post, but gives you the idea. It really stabilized the tool post (had trouble with it wanting to rotate before). You could add one whatever thickness gives you the height needed. Also, are you using 1/4" tools or 3/8"? Mine are 3/8" which might make a difference.
Jim
(https://listerengine.com/coppermine/albums/userpics/10010/P1030423.JPG)
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It helps to have an insert in the holder. :facepalm2:
Photo shows the insert within adjustable range without the base under the QCTP, the bolt is now fully engaged with more to spare, but I'm near the end of the range of height adjustment.
So yeah, I'll need the plate under the QCTP which will also minimize rotation of the tool post.
What did you all do to prevent the tool post from rotating on the plate?
Have you got a sketch or drawing of the plate?
In your picture, Jim, are you using 3 T-nuts?
Now...off to Home Depot to get the items needed to make the bases for the machines.
Initially I was going to mount the machines to my lab workbench but I didn't like the idea of drilling holes in the bench and it would set a terrible precedent if I needed to move the machines.
It is also true (as mentioned in the documentation) that mounting directly to the workbench will amplify motor noise and vibration.
With a machine on a base with rubber feet, I'll be able to move the machines around.
I'm limited to a 5' long workbench and this will allow me to move the machines around as I need them.
Hopefully they won't walk on their own.
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:lolb:
I used small countersunk screws through the plate up into the base of the qctp, to lock them together.
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:lolb:
I used small countersunk screws through the plate up into the base of the qctp, to lock them together.
Same as Chris, Zee.
I use the 2 Tee Nuts you see, plus the one on the QCTP itself. Makes it easy to rotate the tool post as needed. Before I got my plate made, I put a piece of sand paper under the QCTP, which helped some.
The small rubber feet on the bottom of my bases keep the machines from sliding around just fine.
My bench is 5' and has plenty of room to work.
Jim
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Zee:
I machined a block with a square recess (#35) (http://www.modelenginemaker.com/index.php/topic,7227.30.html) matching the base of my QCTP. Made one minimal height and one to match riser blocks on the lathe. The advantage is I didn't have to drill holes into the QCTP. One downside is the tool post can't be rotated.
The T-nuts from Sherline are very short. I made a bunch of T-nuts more along the lines of standard tie down T-nuts. For the QCTP I used a longer T-nut for more holding, spread the load toward the edges of the QCTP. Also use them for general purposes.
Thanks.
What did you all do to prevent the tool post from rotating on the plate?
Have you got a sketch or drawing of the plate?
In your picture, Jim, are you using 3 T-nuts?
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Now...off to Home Depot to get the items needed to make the bases for the machines.
Initially I was going to mount the machines to my lab workbench but I didn't like the idea of drilling holes in the bench and it would set a terrible precedent if I needed to move the machines.
It is also true (as mentioned in the documentation) that mounting directly to the workbench will amplify motor noise and vibration.
With a machine on a base with rubber feet, I'll be able to move the machines around.
I'm limited to a 5' long workbench and this will allow me to move the machines around as I need them.
Hopefully they won't walk on their own.
I mounted my Unimat to a plywood base large enough that I can, when necessary, clamp it to the workbench with a bar clamp. The plywood is also fitted with a steel plate in the area behind the lathe. This gives me a footing for a magnetic base indicator holder. If the steel plate is made thick enough (mine isn't) it could be drilled and tapped to hold other accessories (e.g. lights, drip oiler, etc.)
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And give the wood base a good coat of tough porch paint or something so it does not soak up oil.
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Thanks all.
I'll work on the QCTP a little later.
I got the bases built and installed. I used a white shelf from Home Depot. It's covered in some kind of plastic so I don't know if painting is needed at this point.
They're a huge improvement in stability and noise but I notice the mill vibrates a bit. I don't know if that will be a problem.
(Be sure to drill from the top side. The board tears a bit when the drill bit gets through.)
Went through Hugh's thread. Lots of neat ideas there.
Thanks Marv. I like the idea of putting a plate behind the lathe. That's another to-do.
Concentrating on the lathe for now...
Reviewing all the various adjustments (backlash, etc.) and alignments.
I should be able to cut some metal in a day or two. Probably just face and turn a bit of rod and try some drilling and parting.
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Overall things on the lathe seem to be nicely adjusted but I haven't checked the squareness of the headstock yet.
:help:
However, I'm having troubles with the cross slide (X axis).
The biggest problem is the handle (lead screw rather) moves significantly left/right. Even with the cross slide fairly well engaged.
See the attached pictures. (The insert is there for reference.)
A smaller issue is the brass round nut at the end of the lead screw that goes against the saddle. It's rotation is prevented by a 'knurled' similar round nut next to it.
See attached picture.
I can't get that round nut to seat against the saddle.
On top of that, the ring (at the handle) with the zero mark rotates slightly as I turn the handle.
And, I can't zero the dial. It won't budge. I don't have the same problem on the Y axis. Nice and tight and I can zero the dial.
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Thanks all.
I'll work on the QCTP a little later.
I got the bases built and installed. I used a white shelf from Home Depot. It's covered in some kind of plastic so I don't know if painting is needed at this point.
They're a huge improvement in stability and noise but I notice the mill vibrates a bit. I don't know if that will be a problem.
(Be sure to drill from the top side. The board tears a bit when the drill bit gets through.)
Went through Hugh's thread. Lots of neat ideas there.
Thanks Marv. I like the idea of putting a plate behind the lathe. That's another to-do.
Concentrating on the lathe for now...
Reviewing all the various adjustments (backlash, etc.) and alignments.
I should be able to cut some metal in a day or two. Probably just face and turn a bit of rod and try some drilling and parting.
That plastic covering is called Melamine. No further treatment needed. Masking tape can help tearout from drilling, as can using a brad point drill bit. I used another piece of shelving for a backstop for both the lathe and mill. I was then able to screw some holders, for accessories, to that.
Here's a link to a scribe that Clickspring made on his Sherline lathe: https://www.youtube.com/watch?v=o8Bd8G21Vv8 It was my first ever machining project. You didn't mention if you have your Compound yet, but it uses that as well.
Hugh has made some really neat accessories for the Sherline lathe and mills.
Jim
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Zee - two things on the cross slide leadscrew.
The brass nuts underneath control the backlash on the threads. To adjust that, you loosen the screw on the knurled ring on the side, turn the one on the leadscrew, then tighten the screw again.
But First:
The handwheel is what keeps the whole table from sliding off the leadscrew, that is where your main problem is. If you turn the graduated dial on the handwheel (loosens/tightens with the thin knob on the end) so that you can see the setscrew underneath (is that way in your photo), you can fix this. move things so you have the gap between the bed and the handwheel. Loosen that setscrew, and push on the table so it is pushing the leadscrew towards the handwheel. At the same time, push the handwheel in to close the gap. Then tighten the setscrew again. When you rotate the handwheel, you will likely still see around four or five thou of turning (as shown on the dial) before the table moves - this is normal, and is about as good as it gets. If you are seeing 10 or more thou, then the handwheel needs to go in more. That setscrew will make a divot on the end of the leadscrew rod, so you may need to turn the handwheel to a new position if it slips back into its old spot every time.
Once that is adjusted, then you can see if the brass wheels underneath are needing adjustment. Also, make sure the gib is in far enough to give some resistance to movement.
On my mill, I made a replacement handwheel that has a way of taking up that slack, but if you are going to put the CNC handwheels/motor/leadscrew in, you wont need that, the CNC version has a preload nut that fixes this flaw in the Sherline design. For some reason they are very reluctant to change anything that Joe Martin designed, even if a simple change will improve things a lot. He did a wonderful job, but any design can be improved.
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Thanks Jim.
Thanks Chris. I'll try that out. I will likely have more questions as I didn't quite understand everything.
A few other questions...
1) The tailstock, when not locked down, wobbles quite a bit. Once locked it is very stable. Is that expected? Will it be aligned properly? (I haven't measured yet.)
2) On the mill, I can lock the Z axis. I'm still hunting for a way to lock the X and Y. Is there a way? I see a knob to the left of Y but I can't move it.
3) Same thing for the lathe. It's not clear to me how the axes get locked.
(I'll probably do some googling this evening...but you guys are easy. ;D)
In any case, I couldn't help myself and did some cutting.
See attached picture.
On the mill I flycut the top, center drilled and drilled a hole, and took a pass with an end-mill. I was impressed. (However I have no idea how the flycutting did as the surface is nearly smooth as glass and devoid of machine marks. (Again, I haven't checked squareness on anything yet.)
On the lathe I faced, turned, center drilled and drilled a hole, and parted. Again I was impressed. Best surface I've ever seen (in my shop).
I may be moving to CNC sooner than I'd thought.
First though I need to rearrange the shop. I want to figure out a way to have all my machines in the back of the shop, arranged in a way to minimize swarf everywhere. I'm trying to get a 4x8 table in hoped of building a small railroad (I have grandchildren! Yeah.)
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Zee:
I don't think you want the brass round nut to seat against the frame. It is for backlash adjustment, you loosen the screw holding the meshing brass round to be able to turn the round nut. Once the backlash is taken out by rotating nut till "snug" tighten the screw to hold both in position. If the round nut were able to seat against the frame it would mean you're out of adjustment. See the Sherline directions.
A smaller issue is the brass round nut at the end of the lead screw that goes against the saddle. It's rotation is prevented by a 'knurled' similar round nut next to it.
See attached picture.
I can't get that round nut to seat against the saddle.
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Hi Zee,
The tailstock wobbling when not locked down is normal, you would only use it locked down.
For the mill table, there is a knob on the left side under the table, that is the one that Jim and I both suggested the replacement for, the little stepped block. The knob they provide will slow movement, but not lock it. That one controls in/out movement. For left/right movement, there is a SHCS on the front right of the leadscrew, on a little rounded bump. That is the lock - tightening it will lock the left/right movement. Also can be snugged just a little to give more resistance like the gib does.
For the lathe, there is no lock for the carriage.
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Zee:
I don't think you want the brass round nut to seat against the frame. It is for backlash adjustment, you loosen the screw holding the meshing brass round to be able to turn the round nut. Once the backlash is taken out by rotating nut till "snug" tighten the screw to hold both in position. If the round nut were able to seat against the frame it would mean you're out of adjustment. See the Sherline directions.
A smaller issue is the brass round nut at the end of the lead screw that goes against the saddle. It's rotation is prevented by a 'knurled' similar round nut next to it.
See attached picture.
I can't get that round nut to seat against the saddle.
Actually it should be against the frame - it has a stepped back that fits into the hole, and should be all the way in. Adjusting the handwheel should push it back in all the way.
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Zee:
I'd suggest, for CNC, that you put the machines in enclosures. A simple box with folding plexi front cover. That does a good job of keep swarf inside, then a shop vac can take care of it. The only pain is cutting fluid if you have to open the doors to apply. The Sherlines are small enough the enclosures aren't gigantic, but would make them more clumsy to move around.
I'll soon be setting up my shop more permanently and plan to build enclosures for my Sherlines. I also want to make up small mist coolant systems for them. That will eliminate hand application of cutting fluid for the most part.
First though I need to rearrange the shop. I want to figure out a way to have all my machines in the back of the shop, arranged in a way to minimize swarf everywhere. I'm trying to get a 4x8 table in hoped of building a small railroad (I have grandchildren! Yeah.)
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Crueby:
I'm wrong, and you're right. I though the nut was threaded into the frame but it's a slip fit on the outer OD. So its shoulder has to go up against the frame to work against the main nut and reduce backlash.
Thanks.
Actually it should be against the frame - it has a stepped back that fits into the hole, and should be all the way in. Adjusting the handwheel should push it back in all the way.
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Crueby:
I'm wrong, and you're right. I though the nut was threaded into the frame but it's a slip fit on the outer OD. So its shoulder has to go up against the frame to work against the main nut and reduce backlash.
Thanks.
Actually it should be against the frame - it has a stepped back that fits into the hole, and should be all the way in. Adjusting the handwheel should push it back in all the way.
No problem - I only know since I had to replace the one on my lathe last year, finally wore it out!
:cheers:
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No problem - I only know since I had to replace the one on my lathe last year, finally wore it out!
:cheers:
I'm surprised you wore a piece out already Chris. You've hardly used your machines! :lolb:
Jim
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:help:
Haven't had time today to work on the machines (infant grandson wasn't interested in napping) but I had a chance to learn more about the stepper motors and the G540.
Crud.
The motors have 8 colored wires.
The motor can be wired as unipolar, bipolar serial, or bipolar parallel.
What wiring diagrams I can find...the wire colors don't match (not surprised).
Check me...
The choice would be between series and parallel.
In series there is more inductance and less current per phase.
In parallel there is less inductance and more current per phase (motors get hotter but higher speed is possible).
It's not clear to me which provides more torque at low or high speed. I'm thinking parallel.
I'm leaning towards serial. The current per phase is half that in parallel. What do you think?
Got some wire and wire protection ordered.
Also ordered an e-stop (which is probably rated way higher than needed but I want it to look like an e-stop and be latching).
Ah. Grandson has gone home to daughter. Now I can...no...I can't. It's after 5. Stinking Hoppie time.
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If you turn the graduated dial on the handwheel (loosens/tightens with the thin knob on the end) so that you can see the setscrew underneath
This is going nowhere.
I can't turn the graduated dial relative to the handwheel at all (lathe cross slide only but I find all the other handwheels to be hard to turn relative to the graduated dial).
As it turns out, it's located such that I can see where a set screw would be. But no allen key fits. I'm suspecting there is no set screw.
I've tried imperial and metric (although I suspect all the set screws, bolts, etc) are imperial. No?
For that matter, I don't see a setscrew on any graduated dial/handwheel.
As for that thin knob - I can turn it on all handwheels except the lathe cross slide. I'm suspecting that's the problem. Pliers?
I'm tempted to take pliers to the thing but to what end?
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Zee,
Yes the thin black knob is what releases the graduated dial, I suppose that it could be so tight that you can't move it by hand. If that is the case you don't have much choice but to use a tool on it.
I would attempt to pad it with a cloth or something it may not take much to break it loose. Align the hole in the graduated dial with the hole in the hand wheel then use a 3/32 Allen wrench to loosen the hand wheel.
Dave
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If you turn the graduated dial on the handwheel (loosens/tightens with the thin knob on the end) so that you can see the setscrew underneath
This is going nowhere.
I can't turn the graduated dial relative to the handwheel at all (lathe cross slide only but I find all the other handwheels to be hard to turn relative to the graduated dial).
As it turns out, it's located such that I can see where a set screw would be. But no allen key fits. I'm suspecting there is no set screw.
I've tried imperial and metric (although I suspect all the set screws, bolts, etc) are imperial. No?
For that matter, I don't see a setscrew on any graduated dial/handwheel.
As for that thin knob - I can turn it on all handwheels except the lathe cross slide. I'm suspecting that's the problem. Pliers?
I'm tempted to take pliers to the thing but to what end?
Zee,
The Allen wrench that fits my dials is a 3/32. I think it came with my equipment.
The thin black knob on the hand wheel on my cross slide only turns about 1/4 turn from lock to unlock. It might be worth trying to gently turn it counter clockwise with some pliers.
I'm sorry to hear you're having to deal with these issues. Both my lathe and mill worked great right out of the box. It looks like Sherline may be falling down on their set up procedure.
Jim
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Yup, the setscrews are all imperial. If that knob wont turn on a brand new machine, I would call sherline and see what they say. Between that and the backlash star wheel, sounds like someone there drank lunch that day. Sure that they will stand behind it.
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:help:
Check me...
The choice would be between series and parallel.
In series there is more inductance and less current per phase.
In parallel there is less inductance and more current per phase (motors get hotter but higher speed is possible).
It's not clear to me which provides more torque at low or high speed. I'm thinking parallel.
I'm leaning towards serial. The current per phase is half that in parallel. What do you think?
You'll want to use the parallel wiring if your drivers are capable. The lower inductance and higher current are both beneficial, the current helps with more torque and the lower inductance will achieve greater speeds (or more torque at equivalent speeds compared to series).
The trade off is higher current uses more power - but this is not the concern here, especially as when a motor is "idle" on a cnc it may not be actively moving but might very well be actively holding position..
Mike
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Thanks Dave, Jim, and Chris. I took pliers to the thin knob and managed to loosen it. Finally found the set screw. It turned out my 3/32 didn't quite fit which fooled me but I found another and managed to loosen it. Attached picture shows the ring with the zero mark. The small bolt holding the ring to the cross slide is completely loose.
I'm thinking that ring should be tight up against the cross slide and that would take care of the issue.
Thanks Mike. I'm still not sure.
In serial, the current per phase is 2.1A with an inductance of 8.8mH.
In parallel, the current per phase is 4.2A with an inductance of 2.2mH.
The Gecko provides 3.5A. The power supply is rated 48V, 12.5A.
Now, I believe those currents are a bit bogus. The RMS values are about 70% of that. (1.47 for serial, 2.94 for parallel).
With 4 motors running, it looks like either way the 12.5A power supply will do.
A bit more concerning is the inductance. Gecko documentation shows the equation 32 * sqrt(inductance) = power supply voltage.
2.2mH gives 47.5V (which is within the power supply).
8.8mh gives 94.9V (which is twice the power supply).
It's been many many years since I've played in this arena so I'm not sure about anything.
Whether serial or parallel, the same 4 motor leads are used with the only difference being how the other 4 motor leads are connected and they can be connected at the motor.
So I can try both ways easily enough. I just don't want to blow the driver.
BTW the colors of the motor leads mean nothing. Need to go by where the wires are connected to the motor.
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That ring should be tight, definitely.
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Getting to and tightening up the ring with the zero mark seems to have done the trick.
Backlash appears to be 4-5 thou so I'll leave that alone for now.
Thanks for all the help!
As for the mill's Y axis lock, it doesn't seem to do anything. Not sure why but I can't get it turned in enough to slow/stop the axis.
I'll try making that alternative stop Jim and Chris mentioned early in the thread.
That knob didn't come with the machine. It was replaced with a longer one that came with the axis cover.
I had used a promo code when I ordered the Sherline stuff with the expectation it applied 20% off my entire order.
Checking showed I got something just over 16%.
Called Sherline yesterday and they said it applied to the machines only. But they had (mistakenly) applied it also to the CNC retro-fit kits.
But I have an email from the salesperson confirming it was to be applied to the entire order.
Sent an email (with copy of previous email) to the salesperson to check on that.
The difference in cost is over $100 so I'm interested in getting that back.
The person yesterday said the discount was applied automatically by their system so maybe there's a problem in their software or the salesperson was wrong.
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Glad you got the backlash sorted! The ad with the code does say the discount is on machine packages, not everything, still would be a great deal.
Looking forward to seeing some swarf!
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Glad you got the backlash sorted! The ad with the code does say the discount is on machine packages, not everything, still would be a great deal.
Could be although that's not what the salesperson's email says. But, she may have boo-booed.
I won't hold her to it if that's the case. I didn't find out about the discount until later so it's kind of a bonus anyway.
Looking forward to seeing some swarf!
What? Got none of your own? ;D
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Looking forward to seeing some swarf!
What? Got none of your own? ;D
How many buckets-full should I send down to decorate your workbench? :LittleDevil:
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Looking forward to seeing some swarf!
What? Got none of your own? ;D
How many buckets-full should I send down to decorate your workbench? :LittleDevil:
None! One (or more) of your elves may be hiding in it and I've already kicked out enough of them. ;D
I got the full discount from Sherline. I think the salesperson made a mistake in saying the promo code applied to the entire order but she honored it anyway.
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I got the full discount from Sherline. I think the salesperson made a mistake in saying the promo code applied to the entire order but she honored it anyway.
:ThumbsUp: :whoohoo:
Did you talk to Kat? I've ordered so much stuff from them that we're on a first name basis. :naughty:
I was going to send them a "nastygram" telling them they need to set their machines up better before shipping, but now I won't. :) At least not until you get your refund. :thinking:
Jim
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I used to know slightly a woman named Pam who worked for Sherline and went to the shows from time to time. She's a great machinist; I wonder if she's still there.
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I used to know slightly a woman named Pam who worked for Sherline and went to the shows from time to time. She's a great machinist; I wonder if she's still there.
I've talked with a number of the folks there over the years, always very helpful with questions.
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I used to know slightly a woman named Pam who worked for Sherline and went to the shows from time to time. She's a great machinist; I wonder if she's still there.
Apparently so.
https://www.sherline.com/about/sherline-people/
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Did you talk to Kat?
That's the one. All my communication with her was by email.
Her name stuck with me because one of my daughters goes by Kat (Katherine).
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Checked the tram on the mill. Wow. It was pretty good.
Found the lock for the X axis. It was hidden behind the Y axis cover so that may be an issue (when working manually).
I'm thinking the mill is good to go...but see some questions later.
I can't find a lock on either axis for the lathe (Chris mentioned there is none for the carriage (which if he means X axis then that's the same on my bigger lathe).
But I'm very used to locking the lathe in Z when parting or facing.
I suspect locking an axis is not an issue when I go to CNC. Particularly for the mill where you could be driving in all 3 axes at the same time.
I tried checking the tram on the lathe but I'm struggling to figure out how to mount a dial test indicator. Nothing seems magnetic.
Marv's suggestion for a plate behind the lathe may do the trick.
I could also build a holder that fits the carriage.
Crud...I forgot the questions about the mill I was going to ask. Well, it is after 5:00 after all.
I'm thinking of doing a small project before converting to CNC.
Perhaps a couple of finger treadle engines I can give as gifts to the kids.
Any other suggestions? Must be fairly simple. I did candlesticks already.
No cannons. Kids aren't into that. Although I may do one for an old friend of mine.
Ah! I remember now. When tramming the mill, I used a square clamped to the table.
When I went to remove the clamp, the T-nut and bolt were tight. Had to bring out pliers. The bolt had gone past the T-nut and into the table.
I recall people making T-nuts in such a way that the bolt can't pass through it.
What do you do to ensure the bolt can't pass through the T-nut (on these Sherlines)? (I say bolt but probably should be stud.)
I'm having fun.
I've been reading up on documentation for the G540. Lots of good info I can download.
The Smoothstepper is a different story. The site is good but I can't find a downloadable version of their information. I can find things on other sites but I don't know if the versions are correct. This so reminds me of when we changed processor families and compilers back at...that place where I used to make money.
I'm still a paper guy and going back and forth between computers is a pain.
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Zee - here is how I put a dial on the lathe for trueing up and offsetting parts in the 4-jaw, couple simple blocks with a snug fit hole for the indicator, t-nut underneath to bolt it to the cross slide (Jim made one of these too).
(https://i.postimg.cc/CLng0Z1k/IMG-6284.jpg)
For t-nut bolts, there is not much depth to have the nuts with a blind hole, unless you make them stick up higher from the table, which means you have to under-cut whatever you are bolting down. As you can see in the picture, I've down the same thing occasionally, can see some marks in the bottom of the slot. Go to the hardware store and get a selection of socket head screws different lengths, and some washers to put on top - solves that issue.
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Oh - and I like the idea of doing some of the finger treadle engines while its still manual - will give you a better feel for speeds/feeds/etc and what 'normal' cuts sound/feel like on these machines. Who knows, you might get hooked on non-CNC (Come Over To The Grey (oily) Side, Durth! ) :ROFL:
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The Sherline T nuts I have have a restriction just before the bolt would come through the hole. However, I've found that if I tighten them hard enough I can force them past this restriction and still jam them into the table. :facepalm:
If I remember right, there's a procedure in the lathe manual for checking alignment of the head stock by turning a length of material and then measuring the diameter at each end. Speaking of manuals, there's a huge wealth of information in all the manuals (and sheets that come with the accessories). Well worth reading. Also check out all the information by other users that's located on the Sherline website.
Jim
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Jim, remember that Zee was a software engineer, he never reads manuals!!
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Jim, remember that Zee was a software engineer, he never reads manuals!!
Of course........................what was I thinking! :facepalm2: :Doh: :ROFL:
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:facepalm2:
There's a word for you guys...but I'll keep it in the shop. :D
Chris: Yes, I remember that. I should've mentioned it. That gives measurement to the carriage whereas the plate does not (easily).
Jim: I think you're referring to "Rollie's Dad's Method" which is what I was going for.
Jim: None of my nuts have that feature.
P.S. There's actually more than one word for you guys.
P.P.S. And no...they're not pretty.
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:facepalm2:
There's a word for you guys...but I'll keep it in the shop. :D
Chris: Yes, I remember that. I should've mentioned it. That gives measurement to the carriage whereas the plate does not (easily).
Jim: I think you're referring to "Rollie's Dad's Method" which is what I was going for.
Jim: None of my nuts have that feature.
P.S. There's actually more than one word for you guys.
P.P.S. And no...they're not pretty.
I collect those kind of words. Email them! :LittleDevil:
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:facepalm2:
There's a word for you guys...but I'll keep it in the shop. :D
Chris: Yes, I remember that. I should've mentioned it. That gives measurement to the carriage whereas the plate does not (easily).
Jim: I think you're referring to "Rollie's Dad's Method" which is what I was going for.
Jim: None of my nuts have that feature.
P.S. There's actually more than one word for you guys.
P.P.S. And no...they're not pretty.
:Lol: :lolb: :LittleDevil:
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To keep the studs from exiting the bottom of the nut, the standard procedure is to "stake" the bottom of the nut - displace a bit of metal with a punch to obtrude into the path of the stud. Of course, this is harder to do if the nut is hardened ... is it?
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To keep the studs from exiting the bottom of the nut, the standard procedure is to "stake" the bottom of the nut - displace a bit of metal with a punch to obtrude into the path of the stud. Of course, this is harder to do if the nut is hardened ... is it?
File tested one of mine, its fairly hard, file wants to skate but will dig slightly.
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Hmm - if it is medium hard, might do better staking it with a small cold chisel rather than a punch. Won't take much ...
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Of course your first project could be more t-nuts. Then thread depth would be under your control.
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I knew about the feature on the bottom of T-nuts from my other machines. I was just surprised that the Sherline ones don't have that.
It may be that I grabbed the wrong ones but it seems to me that all of them should have that. No?
Currently re-arranging the shop. No new benches or cabinets but somehow I've got less storage than before. ::)
Need to get some plywood and masonite that will be used to create backs to my lab benches and to separate the 'dirty room' from the 'clean room'.
The boards will also be used to hang tools.
Once the shop is in order then I'm hoping to start the finger treadle machines and a 'franken-board' for learning about the Smoothstepper, Gecko, and Mach3.
So far this seems to be pulling me out of my depression. :ThumbsUp:
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My guess is sherline didn't do that since the nuts are so thin, ones on minimills are twice as tall.
Looking forward to seeing your build of the finger engines!
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What a great adventure Zee. I just read through the whole thread and will be following along now. Looks like you have done your homework with the help of others here. Have fun!!
Bill
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Thanks Mike. I'm still not sure.
In serial, the current per phase is 2.1A with an inductance of 8.8mH.
In parallel, the current per phase is 4.2A with an inductance of 2.2mH.
The Gecko provides 3.5A. The power supply is rated 48V, 12.5A.
Now, I believe those currents are a bit bogus. The RMS values are about 70% of that. (1.47 for serial, 2.94 for parallel).
With 4 motors running, it looks like either way the 12.5A power supply will do.
A bit more concerning is the inductance. Gecko documentation shows the equation 32 * sqrt(inductance) = power supply voltage.
2.2mH gives 47.5V (which is within the power supply).
8.8mh gives 94.9V (which is twice the power supply).
It's been many many years since I've played in this arena so I'm not sure about anything.
Whether serial or parallel, the same 4 motor leads are used with the only difference being how the other 4 motor leads are connected and they can be connected at the motor.
So I can try both ways easily enough. I just don't want to blow the driver.
BTW the colors of the motor leads mean nothing. Need to go by where the wires are connected to the motor.
Hi Zee,
Just to be clear the motors and controller aren't from Sherline are they?
I think a poke :stickpoke: to the folks at Gecko is in order to determine the G540's ability to handle the stepper motors wired in parallel. That is the way I would go, the only caveat being that 4.2amps motor draw being greater than the drives specified 3.5amp supply ability. Now some drives limit the amps they supply so it doesn't matter - you could have a short circuit on the output and the drive will limit to its rated amps, others don't have that kind of feature and will try to drive the load and fail (sooner or later).
Not sure about the Gecko - their documentation isn't specific. I would think its self limiting as you can limit the amperage to less than 3.5 amps (with a current
imiting resistor) but I would ask to be safe. :zap: I know that Gecko have been known for great customer support in the past though I've never owned a gecko product myself.
If you have details on the motors (Part numbers, supplier, pictures, wiring colours etc.) I can see what I have or can find. I've hoarded info on that stuff / googled it immensely in the past during my cnc conversions and can probably help.
Mike
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Thanks Mike. That's very appreciated.
Attached is the data sheet on the motor. I got them from Automation Technology. About a 3rd of the price from Sherline.
Along with the information I provided earlier, they are 282 oz/in whether serial or parallel.
NEMA 23, KL23H276-30-8B. Bought through Amazon.
The controller is a Gecko G540, also bought through Amazon.
The Gecko information is pretty good but I can't find a downloadable version of their manual. I can only read the data online.
Good idea to contact Gecko and I have more googling I can do.
I've got the shop rearranged but I'm still setting things up.
I need to make a cover for a wall outlet that's right behind the mill. (Don't want chips getting in there.)
Similarly, I'm enclosing some of the benches so the swarf gets to the floor rather than into the bench shelf.
I'm not thrilled with the shop change. Getting storage where I wanted it is a problem.
Worse, the Sherline equipment barely fits my 5' bench and I think it'll be a problem once the motors are installed.
(The Sherlines have extended beds.)
My backup plan is to move another 5' bench next to it but I lose a work station.
Once the CNC is installed I'll also want to make move-able enclosures for the equipment.
As for the finger treadle project, I've been collecting/cutting the metal for it but the flywheel (due to its size) will be a problem.
Hopefully I'm carving metal in a couple of weeks as well as putting together a frankensystem for learning CNC.
On top of all that, I have to manage Chris's misplaced notion that I'm building a chassis for his Stanley engine. ;D
Funny how a thorn in one's side can live in another state but still poke you.
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Zee:
I found the attached on the Gecko site. It came up as a *.pdf and I saved it from that.
The Gecko information is pretty good but I can't find a downloadable version of their manual. I can only read the data online.
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I found the attached on the Gecko site. It came up as a *.pdf and I saved it from that.
The Gecko information is pretty good but I can't find a downloadable version of their manual. I can only read the data online.
I apologize Hugh for sending you on that quest. I got confused and meant a downloadable version of the SmoothStepper documentation.
Thanks very much.
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As for the finger treadle project, I've been collecting/cutting the metal for it but the flywheel (due to its size) will be a problem.
Do you mean the diameter is too large to turn or the flat area too big to mill spokes on the milling machine as X & Y travel not enough?
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As for the finger treadle project, I've been collecting/cutting the metal for it but the flywheel (due to its size) will be a problem.
Do you mean the diameter is too large to turn or the flat area too big to mill spokes on the milling machine as X & Y travel not enough?
Mainly that I don't have the material. The project calls for a 3" flywheel but all I have is about 2 1/4.
I have a couple of spare flywheels from an old project that I may start with.
Lots of options even the spares are too light (or likely won't look in proportion).
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Zee,
Could probably find something laying around here in the odds and sods and am what, eight miles away?
-Doug
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Thanks Doug.
I had no idea you were that close.
Thanks for the offer. I may take you up on it.
Carl
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Some progress.
Got the shop re-arranged but still a few minor things to do. Not very happy with it but it'll do and I got the space I wanted for a 4x8 table (i.e. a train set).
1st picture shows the various hardware components.
2nd picture shows the franken-system ready for wiring.
The current plan:
1) Install Mach3 and connect it to the SmoothStepper motion controller and see that it does what it should. (Need to wire 5V power supply and emergency stop at a minimum.)
2) Connect the G540 driver and use Mach3 to drive the two motors. (Need to wire the 48V power supply and motors.)
3) Convert the Sherlines to CNC, install the above hardware, and have a go.
My plans usually go awry as I don't have Baldrick as an adviser.
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Those are the same e-stop buttons we used to put on all our printer test fixtures, for when a sensor wire came loose and it accelerated the carriage at the wall at light speed. They work very well.
Now that you mention Baldrick, make sure you dont think of the BlackAdder theme song or it will get stuck in your head. ... Ooops, too late! :Lol:
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A bit more progress.
I went with configuring the stepper motor phases in parallel.
1st pic shows the DB9 with a resistor used for current limiting.
I doubt the resistor is needed. The motor will take 4.2A per phase but the Gecko will only provide 3.2A.
I also turned off the charge pump on the Gecko (as recommended in a video I'd watched.)
2nd pic shows everything wired up (I think).
Next step is to disconnect the 48V supply and concentrate on the Smoothstepper.
First, I'll disconnect the 5V supply and verify its operation (there's a trim pot to adjust the output - earlier I had measured 5.3V so I want to bring it down a tad).
Then reconnect only the 5V supply, verify the SmoothStepper is operating and configure it and Mach3.
Then I'll move onto trimming the 48V supply, connecting the Gecko and testing that.
I'm not using the remote sense on the 48V supply.
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So far so good.
Trimmed the 5V supply a little. The 48V was fine.
Installed Mach3 and got it talking to the SmoothStepper.
Attached picture shows the top green led solid (it's running!) and the bottom green led (though you can't tell) is blinking which means the ESS is talking to Mach3.
Somewhat easy but confusing. Several re-launches before things seemed to get stable.
Went on to the Gecko. Tried their XML file to configure Mach3 inputs/outputs but that didn't seem to take. So I manually configured some pins.
Also tried the charge pump. Some documentation said it was needed, other documentation not.
When I enabled it, the system faulted. So it's off.
Not sure if the forum will accept the video. It just shows one of the motors spinning when I jogged it via Mach3.
Woo hoo! :whoohoo:
Now to take apart the franken-system and move things over to the machine bench.
Next step is to manually use the machines to get a feel for them before I convert them to CNC.
Off to "Pull My Finger"
[EDIT:] Doesn't look like the video took. No biggie. Just a motor spinning.
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For videos I usually upload to youtube, and post the link from there.
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Now to take apart the franken-system and move things over to the machine bench.
Oops. Getting ahead of myself. Before I take it apart and move it, I'll create and run a lathe and/or mill g-code program and cut some air.
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Now to take apart the franken-system and move things over to the machine bench.
Oops. Getting ahead of myself. Before I take it apart and move it, I'll create and run a lathe and/or mill g-code program and cut some air.
Make sure you anneal the air so it cuts easier!
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Now to take apart the franken-system and move things over to the machine bench.
Oops. Getting ahead of myself. Before I take it apart and move it, I'll create and run a lathe and/or mill g-code program and cut some air.
Make sure you anneal the air so it cuts easier!
It's my shop. The air is always annealed. ;D
Either by words or deeds.
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Not being able to use my left thumb, I've put my finger treadle project on hold and now learning more about CamBam and Mach3.
One area I've always had trouble with is 'speeds and feeds' or 'cutting speed and feedrate'.
I think I've got a handle on cutting speed where the idea is to determine spindle speed.
I know there's several ways to calculate or estimate RPM. Here's one...
RPM = (SFM / diameter) * 3.82 * correction factor
SFM (surface feet per minute) seems to be a value taken from a chart of materials.
diameter is the diameter of the workpiece (lathe) or tool (mill).
3.82 is a constant (some people use 4, others use pi).
The correction factor seems to depend on tool type (HSS or carbide). For example if carbide is used then the factor is 2.
Finding said chart has been difficult and I'm not sure there's agreement across the board.
It seems to depend on material type, material hardness, mill or lathe, tool type, drilling or not, etc.
Question...what do you people use to determine spindle speed?
I'm not doing production nor looking to be a 'professional'. I'm looking for rules-of-thumb.
I'm having more difficulty with feed rate which seems to be a function of the number of flutes and depth of cut (or size of chip).
Question...what do you people use to determine feed rate?
This all sounds fundamental and even though I've been at this hobby for some 10 years...I've been winging it.
Having played with the machines for a little bit, I've decided to convert the lathe first. I may end up not converting the mill (or at least waiting until I have a project where it would be an advantage).
Thanks
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I've mostly been using the tool library that comes with F360 as a basis for speeds and making small adjustments mostly reduction in feeds. I also look up the charts from the tool makers who give speeds and feeds for various materials and type of cut/cutters.
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Zee
Charts and graphs are all well and good but there is nothing better than experience
I you look at you tube video's of CNC mills the tool is running at 10k rpm and the feeds are whizzing around, don’t try to emulate.
Basic principles say for a 1/4in dia end mill, ere on the cautious side to start with
For steel speed 1k to 1.5k rpm feed 2-3 in per min plus suds
Brass speed 2k to 3k rpm same feed to start with
Aluminium same as brass but needs suds as ali is very sticky
There are special cutters for ali with wide gaps between flutes to avoid sticking
Just go slowly and be VERY aware of G0 rapid movement, its faster than you can get to the E stop.
Good luck and enjoy CNC when you get used to the process it is very rewarding.
Mike
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Zee, if you watch any of my videos in the "over to the dark side" thread on youtube I usually put the cutter, speeds, feeds, cut etc in the description so that may give you an idea of what works on my machine.
Typically for a 6mm cutter on steel I would be 2.5-3K rpm feeding at 200-400mm/min Aluminium would be at my max 5000rpm.
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I can recommend that you buy G-Wizard for f&s. I have recouped its cost many times over in tools that I didn't break and work not gouged.
cnccookbook.com
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I've found G Wizard very helpful as well. The program lets you vary feeds and speeds to minimize cutter bending
Chuck
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I've tried a few F&S calculators and didn't get on with them. I'd rather compute my own numbers based on experience and manufacturer data. The two important parameters are spindle speed and chip load (which determines feedrate).
For spindle speed as a starting point I use the figures in Machinery's Handbook. I might downgrade them a bit especially for tougher materials like stainless steel. I simply divide the wanted cutting rate (feet/min) by the circumference of the cutter (diameter x pi) to get a spindle speed. For smaller cutters (<6mm) my CNC mill is often the limiting factor.
I take chip load (in thous) values from manufacturer datasheets, plus experience of what worked. Feedrate is chip load times number of flutes times spindle speed. The chip load varies with the type of cut. A full width and one diameter deep cut will be at a lower chip load than a full depth, but shallow width cut. Read up on chip thinning.
For finishing I usually climb mill but for roughing I use both, otherwise the cutter spends ages lifting and traversing to the beginning of the cut rather than just going back and forth and cutting in both directions.
Of course one needs to take into account the size and rigidity of the mill. I learnt that it's better to use smaller cutters running at high spindle speeds and feedrates rather than larger cutters running more slowly as one might do on a manual machine. I rarely use cutters bigger than 10mm on my CNC mill.
I use YG cutters (Korean) and their speed and feed tables seem pretty reasonable. Certainly not the all out industrial stuff you see on youtube. The biggest problem is that for cutters smaller than a few millimetres my mill runs out of spindle speed.
There are two important points to note. Do not feed too slowly, the cutter needs to cut, anything else just rubs the cutter and destroys the edge. This is just as important on a hobby CNC mill as an industrial mill. The metal and cutter do not know what sort of mill they are on. Second get rid of the swarf either by flood coolant or airblast. Nothing fudges a cutter quicker than recutting swarf.
I normally do a roughing pass and a small width of cut finish pass to get the best finish.
Andrew
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The problem with 'experience' is that I virtually don't have any and what machining I've done is without knowing what feed rate or speed I was using. I mainly did what sounded and looked okay.
Experience equates to months, if not years, of learning so I can't depend on that yet.
Going through various documents and videos has been frustrating. Too often I come across statements like "and calculate X using the desired Y" but I have no idea what Y is.
I'm looking at the setup screen for G-Wizard.
I found the min/max spindle speed for the lathe.
Spindle Power was an issue. I came across 70 watt for the Sherline which I believe is 60/745.7 = .08 horsepower. No?
Now I'm stuck again on 'max feedrate'. No idea and can't find anything other than one statement that seem to indicate something around 18 ipm.
I'm a procedural kind of guy and this stuff is exceedingly frustrating.
As for the Machinery Handbook. $72 and I don't know what it provides. Some charts for speeds/feeds? Is that the only source? What else does the book provide for the hobbyist?
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Zee, I find Machinery's Handbook useful from time to time ... and sometimes interesting just to read through bits of it. But I wouldn't spend $72 on it. I bought a copy well-used for a few bucks many years ago, but since then I've discovered that there are some .pdf scans of older editions on the internet. Not sure how legit they are, but I think - ?? - there may be a Google Books version, which I would presume to be legal.
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I have to admit I'm really in the dumps.
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The only pages in Machinery Handbook I have used many times are those with the specs on threads when I wanted to single point. On occasion I might look up something new, but I haven't opened my copy in a long while.
Max feedrate is whatever your rapids are set to.
The Sherline DC motor is .06W at 6100 RPM, but is higher at lower RPM. It replaced a 1/2 HP motor according to Sherline.
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Hi Zee, as machining was never even a tiny part of my work experience, my hours of hobby experience may not be too far ahead of you, but I am fortunate to have a very experienced mentor. But the spread out nature of hobby work means I have to do a lot of learning over and over again.
One of the best tips was his starting point for cutting speed which is to assume 500 rpm for a 1/2 inch or 12 mm workpiece on the lathe, for high speed steel tools cutting carbon steel. Then rpm is inversely proportional to the workpiece diameter. So for 1 inch dia use 250 rpm, but for 1/4 inch use 1000. You can also work out the surface speed in FPS or m/min as you prefer, but these days I work with “easy to remember”.
This same approach is the reason for the very high speeds people use with tiny cutting tools on CNC machines.
My machine has a nine speed gearbox, so only limited speeds available. Use the nearest one, higher or lower as you wish, lower for a first trial if you are not confident, or for interrupted cuts and parting. But hey are not that critical.
Then aim for half that rpm on stainless steel to avoid heat causing work hardening. I have no trouble with type 304 or 316 on this basis and enjoy working with them.
You can use higher speeds for brass, bronze and aluminium, but my max speed is 1600 rpm and I am fairly sure older machines only go to 1000. This never stopped the old timers from making parts.
My understanding is that industrial calculations are aimed at the minimum cost to machine a part, including the cost of time for tool sharpening. So they go to much higher speeds, and sharpen more often as necessary. They also have the power necessary to cut at these speeds. Clearly hobbyists generally prefer to minimise the need for sharpening, so slower speeds are in order. I have tried to find information about whether too slow can also be a problem, but have not found anything so far. But very slow speeds do make it harder to cut, as you find on a facing or parting cut where the cutting speed varies as the remaining diameter reduces, but the above guide seems to fit nicely between too fast and too slow, and high speed steel tools last a long time between sharpening, apart from the occasional touch with a small stone before a critical cut, more for me than for the tool I suspect.
For the milling machine the tip speed of the tool rather than the work piece diameter.
Insert tools need to go much faster, but I rarely use them, others will have to answer for them.
Like others I was at first disappointed with the brazed tip tools, but once I was shown that they do not come sharpened, I am finding very good results, at faster speeds. You need the appropriate wheel on the grinder, but once done they stay sharp really well.
I only have manual machines, so judge feed by feel and finish and probably normally too timid. Tool supplier recommendations are probably aimed at industrial users, so I would guess something between those feed recommendations and just rubbing gives a broad area to experiment in, and again probably not too critical when “time is not of the essence” as one supplier always replied to our commercial people, who always included the opposite in the contract conditions. I would start a bit slow for a trial cut, and if you are getting a healthy chip production, and somewhere within guidelines, it will probably be ok, but I will leave it for other more experienced members to refine the suggestions.
This is getting too long as usual, so boring bar holders another time if still of interest.
Your machines certainly arrived at a good time for the opportunity to play with them while you learn. And great job on those finger treadles, keep them going.
MJM460
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Zee:
I've looked at Machinerys Handbook for feed and speed. It is quite complex and I don't think too useful for hobby use. I believe it's for commercial applications where they are trying to get the "most" out of a process. It pushes the tools harder than we would want to, the time vs tool wear is different for us. Machinerys Handbook is very useful for other information, but I usually find an Internet search easier.
I found a feed & speed calculator at The Little Machine Shop. (https://littlemachineshop.com/mobile/speeds_feeds.php) Just input units, mill/lathe, material to cut, HSS/carbide, diameter, and # cutting edges. Hit calculate and it gives back spindle speed and feed rate. Likely a good starting point.
You need spindle speed but seldom feed rate for manual machining. But for CNC you need to put in a number for both. Even when jogging or using MDI commands you have to tell it something. You'll get a feel for these as soon as you start using the CNC.
Your mileage may vary.
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Zee
Don’t be in the dumps, by experience I meant your experience by trying different speeds and feeds.
A rough guide if the machine makes a lot of noise and the chips are dark colour and getting hot then you need to slow things down.
However, if the machine makes no more noise than without cutting and the chips are bright and shiny then all is well.
Just try things and you will feel better
Mike
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Hi Zee,
Mach 3 has a very handy Speed Over-ride that lets you decrease or increase travel speed during on the fly. If things are getting out of hand, just slow up. Dawdling, increase.
All the best,
Martin.
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The problem with 'experience' is that I virtually don't have any and what machining I've done is without knowing what feed rate or speed I was using.
.............
I'm a procedural kind of guy and this stuff is exceedingly frustrating.
As for the Machinery Handbook. $72 and I don't know what it provides. Some charts for speeds/feeds? Is that the only source? What else does the book provide for the hobbyist?
I've got three copies of MH, one 1992 that I bought at the SAE show in Detroit, one 1943 that belonged to my father when he was doing his apprenticeship and one 1948 that belonged to the father of a gliding friend who was a toolmaker. The speeds and feeds in MH are based on experiment, not made up as a lot of the ME stuff is. Of course MH is based on industrial experience but there's no reason not to cut at the same speed as industry, albeit reducing width and depth of cut for smaller machines. If using inserts and/or carbide milling cutters they don't always work well at slow speeds. For instance a TiAlN coating needs to run at many hundreds of degrees to be effective. I use MH for, among other things:
Geometry equations
Moments of inertia, section modulus and radii of gyration
Deflection equations
Strength of beams and buckling equations
Gear design
Speeds and feeds, alhough I have some problems with the US material numbers
Wire gauge information
Materials and techniques
Tapers
Loads of information on threads - metric/BSW/BSF/BA/BSP/NPT, sometimes UNC/UNF as well as square and ACME
Plus other things!
Experience starts to be gained the moment you write down what you do and learn from it rather than winging it. Doesn't matter if it's wrong but learn from it and make adjustments. Most people feed too slowly. It took me a while to learn that the answer to chatter when milling is often to increase feedrate. Remember that at the end of the day cutting tools are consumables. They don't last for ever. I've broken very few cutters due to over ambition, although I have stalled all my machine tools except the horizontal mill, so I know where the machine limits are. I've mostly broken cutters due to finger trouble and on occasion due to material problems.
Andrew
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Rather than spend a lot for MH, check your local library book sales. When starting out, I paid a lot for a 23rd edition. Since then I've acquired at least four at library sales, each for less than a dollar (folks at these sales are looking for romance novels, not engineering books so the prices of the latter are very low). My bargain buys included one from my birth year and a 24th edition - a year later than my original, expensive buy.
Another typical bargain was a 1944 printing of "Shop Theory" from the Henry Ford Trade School for $1.
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Thanks everyone for your support. :ThumbsUp:
Today I thought I'd try to find some success by playing with Mach3.
I have to say, whoever says this system is plug-n-play is full of crap.
After a number of reinstalls, reboots, and reading...I got the motors to run again.
My hope for this thread as any kind of help or reference has been dashed.
I'm concentrating on the lathe and it's been confusing when I see references to the Y and A axis as if I'm on the mill.
I believe you can modify the screens but I'm not about to go down that rabbit hole (yet).
I did find a speed/feed calculator in Mach3 so that seems convenient.
Now I must go apologize for the horrible noises that were coming out of my shop this morning.
Next step is to manually write some g-code and see if it runs on Mach3.
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I suggest you work on the mill first and get very comfortable with running and writing or otherwise creating, G code. Mill is by far the most common and you will find lots more experience to help you. You will discover lathe to be the weakest part of Mach3, in fact getting lathe to work consistently was a big reason Mach4 became a full redesign and coding.
I know I have a bit of bias, but I would go to Mach4. It will cost you the addition of some motion controller, like a Smoothstepper or PMDX smartBOB. Mach3 has had no development now for many years- at least 6 or 7, I dont recall exactly. Contrary to many opinions Mach4 is a fully released system being sold into many industrial sites. There are numerous OEMs that bundle it with their machines. You dont see much web traffic about it because it just runs and people are using it, not talking about it. Years ago there was a hobby of building your own CNC machines, and the Mach3 mail list and forums had lots of activity. Now the hobby users mostly just assemble a system and run it.
If you have Mach3 questions the yahoo mail list has been moved to groups.io and has some activity. Question posted there will get response. Machsupport.com is the official site of the Mach business and there are people assigned to follow the site and help users. Although Mach3 is officially 'not supported' you will frequently get help. If you use the Mach3 wizards I can help, and I can help if you decide to get into screens or writing the VB code. I wrote parts of the wizards and am the 'official' support for them, although thats been a pretty quiet activity for a few years, kind of like the old Maytag Man.
If you would like to talk about your issues I am willing to take phone calls at reasonable times. PM me for the contact info. I can even connect into your machine and help find or fix problems.
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I also wonder if you might be better off using CAM to generate your code first rather than trying to write it, I've been able to make quite a few parts and have yet to write a single line of G-code. Not sure what your CAM is like but expect it is similar to F360 where you can run a simulation of what the tool is going to do and actually see it removing the material, it also has a big red warning each time the tool crashes on the simulator which is a far better option that doing it for real on the machine and you can instantly see the affects of changes to feed, speed, tool paths, etc.
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Thanks Ron.
For what I'm trying to do, I don't know the difference between mill and lathe by which I mean, I'm not using any home switches, spindle control, or anything really other than moving a combination of motors.
In any case, I'm interested in the lathe for a couple of reasons 1) I want to make some turned parts with certain curves (very difficult to do manually) and 2) Keep things relatively simpler.
It's possible I won't convert the mill at all.
For now, I seem to have Mach3 running well enough and need to try a g-code program.
Just a reminder, I haven't converted the lathe or mill yet. I just have two motors mounted on a board along with power supplies, the motion controller, and the motor driver.
And just to clarify my statement about plug-n-play being crap. I wasn't referring to Mach3, CamBam, or any of the other components by themselves. Getting all the components to work together has been the trouble where you need to adjust/configure many aspects and have to do some easter egg hunting to find the settings needed.
Jason...that's where I started yesterday using CamBam. Next step is to try a simple part in CamBam, produce the g-code and see that I can transfer it and run it on my frankensystem.
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So I did a CamBam example and generated some g-code. The example is a mount for a nema23 servo motor.
Then I loaded the file into Mach3 and hit Cycle Start (even though I don't have a Y axis).
That's a decent start for me. Now I'll peruse the g-code file, learn what g-codes were used and what they do.
Then I'll start learning more about the terminology, controls, etc.
But I feel like I have a system I can try different things on and learn.
Sorry the focus is wrong when I videoed my frankensystem but you can get the idea.
(It doesn't show both motors running but they do.)
https://www.youtube.com/watch?v=sa6dsB40Zp0
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Just remember that for lathe the spindle axis is Z, with Z0 usually at the end of the work and towards the headstock is negative Z. The cross slide is the X axis with negative X towards you. X units can be in terms of radius or diameter. I personally find diameter to be easiest mentally.
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Thanks Kirk. Yeah that's why I don't have a Y axis.
I'm a little worried...the program is still running. I think I would have been done by now if I had done this manually.
Well...still more to learn.
Again, thanks all for the support.
I feel like I'm being pretty stupid silly but I'm sure glad to be on this forum.
P.S. I may have to let some of Chris's elves into my shop. Going batty. Must be if I'm thinking of letting a stinking elf in. ;D
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Program finally stopped. Took at least an hour.
Supplies are cool.
Driver is warm-ish.
Motors are too hot to touch. That doesn't seem right. Thoughts?
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What size was the part and what sort of cuts were you taking? The CAM simulator should give a time for the job so you know how long it will run.
Not easy to see from the screen but if you have it in imperial than you were taking 0.05" deep cuts, can't read the speed so don't know if the 2"/min feed is right for that.
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Hi Zee, Jason, if this is the chosen spindle speed, it seems to me more than slow.
May be this link on how to calculate for hobby purposes will help.
https://webseite.sorotec.de/download/fraesparameter/schnittwerte_en.pdf (https://webseite.sorotec.de/download/fraesparameter/schnittwerte_en.pdf)
If you cannot archive the in the first calculation recommended spindle speed, than it can be reduced to what is achievable in the second part of the calculation.
I prefer not to overload a cutter.
That means Ap, depth of the cutter into the material 1/5 of cutter diameter in aluminium and 1/10 of cutter into steel.
By milling a slot, that means 1/2 diameter of the cutter and the ground are cutting material , it is better to use even less.
Ae, width of cut (from the side), 1/3 of cutter diameter.
May be this will help you over all to find your way of CNC machining.
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That's one reason I asked the size of the part 972rpm would be OK for certain diameters and if it is large then cutting times will be longer than a small dia part.
Though feed per rev would work out at 0.025" ( 2" /972) which is quite aggressive for a small machine even 0.05" DOC.
Zee if you can post the part file I'd be interested to see what it comes up like in F360 if I base it on the type of cuts I could take with my Unimat. Either the Alibre part file or .STP would do.
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Hmmm, 2"/min feed and 972rpm spindle speed is 2.06 thou per rev. Seems pretty low to me, but I run a bigger lathe.
Andrew
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Thanks guys.
The part was created from an example CamBam, found here...
http://www.cambam.info/doc/plus/SimpleExample.htm
The size is 5" x 2.375" and 1/2" thick.
All the settings were given in the example. Such as 7 ipm feedrate, 2 ipm plunge rate. Tool diameter is 1/8".
There is no spindle control.
All I did was load the g-code file into Mach3 and ran it. I hadn't set/changed any settings in Mach3 (thinking the program does what's needed).
I haven't read the g-code to see what it does.
Attached is, what I think is, the drawing file from CamBam.
I loaded the g-code in the Mach3 simulator and it gave a 59 minute run-time.
The example may not be real-world but was good enough to make some progress.
I'm still curious why the motors got too hot to touch. However, I haven't done any motor tuning or checked what controls there are for setting acceleration etc., or what, if anything, I should do to optimize.
I know there's a procedure for tuning the Gecko drive which I haven't done yet.
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Don't use the 0.9.8 CB files, 1.0 is the official release now.
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Don't use the 0.9.8 CB files, 1.0 is the official release now.
Is there a particular reason or just because it's newer? (1.0 was released end of February but I don't know the year.)
I tried tuning the Gecko driver. The procedure is to run the motor at 2 rev/sec and adjust a trim pot until an audible sweet spot is heard.
I couldn't figure out how to run the motor at 2 rev/sec so I just held the jog button down. I could hear a slight difference as I trimmed the pot but I can't say I detected a 'sweet spot'.
Of course, having lost the ability to hear higher frequencies may be part of the problem.
Lots to learn...
1) If I run a CamBam generated g-code file, what settings on Mach3 need to be addressed?
2) What motor characteristics (if any) need to be set and where? (e.g. maximum acceleration).
I'm still hoping for any thoughts as to why the motor got too hot to touch. Driving too fast? Driving too long? Something else?
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I thought you were running something for the lathe, that looks to be a part milled out of plate :facepalm:
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Zee:
I'd also start by CNCing the mill. It will be more useful and there are far more examples and help available for milling than turning.
If I'm seeing it correctly the example cuts a 1.5" diam pocket 0.064" deep then a 0.5" diam pocket 0.51" deep. I think a 1/8" end mill is small for this part and may be one reason it runs so long. Try to run it again with a 1/4" end mill, which is what I'd use in the Sherline (probably 3/8" in a larger machine). CamBam used 10,000 rpm spindle and 7.0 in/min feed rate, Little Machine Shop calculator suggests 6000 rpm at 7.0 in/min (if 2 flute/HSS end mill in aluminum) so 7.0 seems reasonable. Also, increase the depth of cut from 0.02" to 0.022" for the first pocket. That reduces the number of passes from 4 to 3 (unless you want that last 0.004" pass for finishing.
I understand that stepper motors run hot. Those on my Sherline are too hot to comfortably touch. You're using a Gecko G540? Did you insert the correct resistor for the current control? If not see the manual for value and placement.
Good progress.
P.S. And as Jason says, it is a program for the mill. :-)
EDIT: Speeds should be 7.0 rather than 0.7. Changed in text.
Thanks guys.
The part was created from an example CamBam, found here...
http://www.cambam.info/doc/plus/SimpleExample.htm
The size is 5" x 2.375" and 1/2" thick.
.................
I'm still curious why the motors got too hot to touch. However, I haven't done any motor tuning or checked what controls there are for setting acceleration etc., or what, if anything, I should do to optimize.
I know there's a procedure for tuning the Gecko drive which I haven't done yet.
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CamBam used 10,000 rpm spindle and 0.7 in/min feed rate, Little Machine Shop calculator suggests 6000 rpm at 0.7 in/min (if 2 flute/HSS end mill in aluminum) so 0.7 seems reasaonable. Also, increase the depth of cut from 0.02" to 0.022" for the first pocket.
Wow, those are slooooow feeds, and are why I prefer to do my own calculations. The pockets on these steel parts were done with a 3mm cutter:
(https://listerengine.com/coppermine/albums/userpics/10022/normal_Spectacle_Plate_Bushing_1.JPG)
I was running at 5000rpm and 120mm/min (4.7"/min). I was using a 3-flute end mill but even so 0.7"/min is incredibly slow. For pocketing I was cutting with a width of cut of 75% of tool diameter and 24 thou depth of cut. I left 8 thou for a profile pass which was done at 0.093" depth of cut, ie, 3/32". Machining time for the two pockets in the part on the left was 16 minutes.
Andrew
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Zee's example is running at 7" (180mm/min) not 0.7".
I've just drawn out the part and then used Fusion to do the CAM, not all the details are in the CamBam example as it does not mention speed and only gives depth of cuts (vertical) but no step over so I used approx 2/3rds cutter dia for stepover (0.080") and my max spindle speed of 5000rpm otherwise all as per the example. and it takes 30mins to run.
As said it's not how I would cut it, preferring to use more of the side of the tool and a 1/8" cutter would need long flutes to get through the 1/2" material, also don't fancy trying to get the swarf out of the hole when using it to drill the 3.6mm holes at full depth. Will run the CAM again with some settings that I would use and see what it comes out like.
https://www.youtube.com/watch?v=6VbaBdNF9k8
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I thought you were running something for the lathe, that looks to be a part milled out of plate :facepalm:
Sorry about that but yes. I didn't find a CamBam example for the lathe so I used a mill example.
Remember though, I'm not running on an actual lathe or mill. I'm running a frankensystem that just has two motors turning air.
No doubt that means certain parameters are not optimal but the point was just to run Mach3 and a couple of motors.
Currently trying to create a part in CamBam for the lathe but it looks like I'm missing something. Perhaps a lathe plug-in.
I'll try downloading version 1.0.
...just saw a couple of posts...
The project I have in mind (the spinning wheel) doesn't have any parts (so far) where a CNC mill would be an advantage. All the mill parts are easily done manually.
However there are a couple of parts (legs and finials) that having interesting curves making manual machining extremely difficult.
Given the availability of help with CNC Mill, I can see where it would be easier in learning CamBam and Mach3 but I'm not sure it really reduces the learning curve for the lathe.
Remember...I'm learning on a frankensystem where I only have two motors (i.e. a lathe). No spindle, no tool, no anything else. I could easily add a third motor.
P.S. Max spindle speed is 2800 rpm. Sherline offers a pulley accessory that provides 10000 rpm (which I don't have).
Just saw Jason's post. That seems to indicate the example I used from CamBam is not real world (but was good enough to learn something).
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Just as an example Zee I redid the plate as I would probably cut it using a 6mm cutter and then swapping to a brill bit for the tapping holes. Also used full depth for the pocket and a tame 0.040" stepover and 12ipm feed.. Same cutter for the 1/2" hole ramping down at 2degrees in two passes so only half dia of cutter being used. Peck drilling to clear swarf and it came out at 8mins, even allowing for your slower speed spindle that would come out at abbout 15mins.
https://www.youtube.com/watch?v=8jqjm3J8ef8
I did try the F360 lathe option this morning for the first time and it was quite easy to face a part, rough turn a spigot and then do a finish pass, you could have a go at that to get some idea of the G-code. If you can attach a stp file of the turned column I'll see what it comes out like.
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Thanks Jason. That's interesting and shows there's ever more to learn. Stepover? Choice for 12 ipm feedrate?
What application are you using in the video (I can't read it)?
I'll need to redraw the column and will get back to you.
In the meantime, I downloaded CamBam 1.0 but I didn't see any real change in folders and contents.
I'm looking for 'lathe-test.cb' which according to CamBam is in the 'Samples' folder. But I can't find any 'Samples' folder nor a source for the file.
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Stepover is how far the tool moves sideways each time it goes round that 1/16" deep pocket, I set it at 1mm which is quite a light load and should be the sort of thing your mill can handle eg 0.050" deep x 0.040" horizontal. I would be using nearer to 4mm on my machine and that would still be quite light.
Feed is again light considering the depth and stepover but better to be safe to start with. assuming a 3 flute cutter this would be about 1/3rd of the book feed rate giving a chip load of 0.02mm per tooth rather than 0.06mm.
I drew the part in Alibre as that is what I'm used to and then exported it out as a .stp file which I then opened in Fusion 360 and used that to do the CAM and create the simulation
Yes there are so many variables that can be tweaked to get the best results both in time, tool life and finish and I've only scratched the surface. If you are using mill code then you may be better off with the X&Y motors running as they are the ones that move the most.
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Thanks Jason.
If you are using mill code then you may be better off with the X&Y motors running as they are the ones that move the most.
Good point.
I just registered on the CamBam forum. Odd that I only found 4 references to 'lathe-test.cb' but little else. Looks like a bunch of helpful people though.
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You're using a Gecko G540? Did you insert the correct resistor for the current control? If not see the manual for value and placement.
I did insert a resistor. As for whether it is correct...I used 3.3K ohm which should limit amperage to just under the 3.5A max.
If it helps any, there's no load on the motors. Just a plastic flag to see it turn.
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Zee just so you can see what it is like this is a simple turned part processed in F360. Basic piece of 12mm dia stock faced, spigot rough turned, spigot finish turned and then parted off to length.
You can see the various operations listed down the left side that get highlighted blue when they are taking place. Purple on the simulated part is waste material and green the finished surface. I just set cuts to 0.5mm (20thou) and a 0.25mm (10thou) finish pass. Part has 1mm of waste allowed for on t heend so it takes two passes to face that back to finished surface and so on.
https://www.youtube.com/watch?v=Ke7jnZUQRoU
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Zee's spigot, the mind boggles ::)
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Jason:
Thanks and you're right, the speeds I mentioned should be 7.0 in/min. Original post corrected.
The example does use a drilling cycle for the four small holes. However, it seems to use the 1/8" endmill for drilling. I guess it is just an example.
The step over in that example (from the CB model) is 0.4 (40%). I suspect this is the CB default.
I hadn't considered it but I like your scheme using depth first. It does use more of the side of the tool so tools should last longer. I'll try this next time I cut a pocket. Thanks.
Thanks.
Zee's example is running at 7" (180mm/min) not 0.7".
I've just drawn out the part and then used Fusion to do the CAM, not all the details are in the CamBam example as it does not mention speed and only gives depth of cuts (vertical) but no step over so I used approx 2/3rds cutter dia for stepover (0.080") and my max spindle speed of 5000rpm otherwise all as per the example. and it takes 30mins to run.
As said it's not how I would cut it, preferring to use more of the side of the tool and a 1/8" cutter would need long flutes to get through the 1/2" material, also don't fancy trying to get the swarf out of the hole when using it to drill the 3.6mm holes at full depth. Will run the CAM again with some settings that I would use and see what it comes out like.
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[I did insert a resistor. As for whether it is correct...I used 3.3K ohm which should limit amperage to just under the 3.5A max.
If it helps any, there's no load on the motors. Just a plastic flag to see it turn.
Is the 3.5A max the rating of the stepper motors? Or of the driver?
The more amps you are running through the motors, the hotter they will get. If you don't need as much torque, you can turn down the amps. Of course, you should not run the motors with more amps than they are rated for.
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Thanks Jason. Is that video of F360? How was the g-code generated?
Thanks Hugh. I also found a post-processor setting to use. I suspect I created the example using the default post-processor. I probably should have selected the Mach3 post-processor. I also see a Mach3-Turn post-processor. Not that I know yet what this does.
Is the 3.5A max the rating of the stepper motors? Or of the driver?
Of course, you should not run the motors with more amps than they are rated for.
I have the motors wired in parallel configuration. The current/phase in that configuration is 4.2A.
The Gecko drive provides a maximum 3.5A (but there's some question if that's really true. i.e. RMS or not).
My poor understanding is that the driver will only provide the maximum set by the resistor (i.e. 3.3A) and the fact the motors can take more shouldn't matter.
I chose this motor based on what I've seen other people do but it's been a question whether to wire in series or parallel.
Parallel has twice the current/phase but serial has four times the inductance/phase.
I don't recall now but I think it was the inductance limit that had me choose parallel.
Jason...the first part I hope to make (once I convert the lathe to CNC) is a bowling pin. Attached is an STL for imperial and one for metric. I use imperial.
However, these STLs were intended for my 3D printer and were drawn in the XY plane.
I suspect I need to rotate this or redraw using the XZ plane. No?
I believe that once I import a DXF into CamBam I have to delete everything except the profile line (i.e. 1/2 of the outline).
A fellow on the CamBam forum helped me out in finding the 'lathe-test.cb' file.
I felt really silly as it was in the ProgramData folder which I didn't even know existed (after all these years!!).
Also found it using the 'Tools' tab in CamBam and selecting 'Browse System Folder'. Not that intuitive for me.
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The steppers on my CNC mill (Tormach) get hot after a long run, but not so hot you can't hold your hand on them. So probably around 60°C.
Andrew
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Zee
You can definitely turn down the amperage, 3.2A at 48V ~ 150 watts - so yes they will get hot. Remember incandescent bulbs and how hot they got?
You don't need 150 watts of power to drive the X or Z axis. I think thats 2 times your spindle power?
As for post processors - it can have a big effect. The way that arcs (i.e. G2 or G3 commands) are interpreted and / or commanded can vary and if done wrong on the lathe you'll end up with odd loops in space. I can't help on CamBam or Mach3 as I don't use either (Fusion360 and LinuxCNC for me)
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Yes that was F360 in all the video's. Did not produce the G-code but assume it is the same for milling where I just click the post processor button, though not sure if it actually has Mach3 Turn at least in the unpaid version just Mach3 Mill.
In Fusion it does not really matter what way the part is drawn as in the initial setup you can move the 3 axis about to suit the way the work wants to be machined eg if milling two sides of a part like the curved aluminium one s I posted last week in the dark side thread then I moved the axis for the second curve as the work was moved in the vice. It also lets you work on the 3D image rather than having to use a profile drawn as a DXF as you can see in my last video
Can you post those files as .STP Step files as I'm having a job picking up the axis of the STL files, also check your units as the metric one is about 2ft long.
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Thanks Andrew.
Thanks Mike. Right, that's 2x spindle power. Yes, I've come across references about the G2/G3 commands and loops.
Thanks Jason. I do not see any option for creating an STP file.
I don't know what's happening with the metric file. It loads fine in Cura and looks okay in Cubify Design. Should be 63.5mm (2.5") long.
I'm wondering if the file contains any unit information. If I load the imperial version into Cura, I get an object just 2.5mm high.
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Gcode loops are caused by a mismatch in arc center mode between the CAM and the control. For a G2 or G3 command, the IJK options state where the center of the arc to follow is located. I highly recommend you use incremental, meaning the I and J words state the distance in X and Y to the center from the current position. This is the default setting in Cambam.
https://www.cnccookbook.com/cnc-g-code-arc-circle-g02-g03/
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Gcode loops are caused by a mismatch in arc center mode between the CAM and the control. For a G2 or G3 command, the IJK options state where the center of the arc to follow is located. I highly recommend you use incremental, meaning the I and J words state the distance in X and Y to the center from the current position. This is the default setting in Cambam.
https://www.cnccookbook.com/cnc-g-code-arc-circle-g02-g03/
Crop Circles, I used to struggle with them years ago when I first converted my mill; mostly due to using cutter comp at the control. When I quit using cutter comp and let the CAM software deal with it, the problem pretty much went away. When hand coding it is easier to let the control do the cutter comp as you have one thing less to think about. But with the modern CAM systems I'm not sure why anyone would want to do that anymore.
Dave
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Progress of sorts.
Found a video that showed a simple CamBam part (like a spigot!) with roughing cuts followed by finishing cuts.
Managed to create a g-code file.
Loaded that into Mach3 and was quickly confused. Didn't look right when I ran in simulation mode. In fact, it looked more like it thought the part was in a mill.
When I had installed Mach3, I had created both a mill and a lathe profile. It doesn't look like the lathe profile was setup right (or something).
Instead, I took the Mach3Turn profile that came with the app, configured the port and pins, and found myself looking at the part I wanted. :pinkelephant:
So I ran it.
https://www.youtube.com/watch?v=BALlxbWVDFA
So far everything looks as expected but you can tell something is wrong. The part is nearly 2" long but the Z axis motor only rotates maybe once as it traverses.
Somewhere there should be a setting for configuring the gear ratio etc that says the motor has to turn so far to move a given distance.
I also recall something about handling backlash and various offsets that I need to look into.
I will admit, I'm still vacillating between giving this up (it's way more work/learning than I had counted on) and plowing on.
I'll plow on some more.
A little :cartwheel: goes a long way.
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But with the modern CAM systems I'm not sure why anyone would want to do that [use cutter comp] anymore.
Using cutter comp makes it easy to make corrections for the finished size, without re-posting the program. However I'll admit I do not use cutter comp for roughing passes. I rely on the correct tool radius and the roughing allowance in the CAM software. Its close enough for roughing.
That is for 2D and 2-1/2D. For 3D my CAM package will post for cutter comp, but the CNC mill cannot deal with it in its tool offsets. So I rely on defining the tool nose radius in the CAM package and posting 'without comp'. Generally when doing full synchronous 3D, the results are close enough because typically it is a sculpted surface replicating a casting or forging (a forgery!), that short of a CMM, I cannot inspect anyway. It has to visually look right more so than meet a particular tolerance. But if it did include a feature of size that I could measure with normal workshop measuring instruments, then I would have to define the tool in the CAM package as larger or smaller radius than it really was to get the desired feature size. Usually those features can be split out and done with other tools using cutter comp.
-Doug
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Cambam doesn't generate cutter comp in g-code. I've used it for dialing in threadmills but needed to edit the code to add the G4x codes.
As for the z axis motor, it needs to be configured to match a hypothetical leadscrew.
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Zee:
That video looks like a lathe part to me. Don't know if the dimensions are coming through, zero set appropriately, inch rather than mm, etc. But the first thing to do is get the scaling set right. Did you configure "steps per inch" in Mach? It sounds like you've not done that yet.
I think the G540 has 10 microsteps built in. i.e. it takes 10 pulses from the computer to move the motor one step. I suspect you have steppers that require 200 steps per revolution. Also, the Sherline lead screw has a pitch of 20 threads/inch (if your machines are inch rather than mm). Motors directly driving the lead screw. So:
10 * 200 * 20 = 40000 pulses/inch
You need to set this in Mach. Since I use LinuxCNC I don't know how to set it in Mach. There's a lot of information if you do a search for "Mach steps per inch". I think you're better off calculating this than measuring machine motion. Then measure machine motion to verify the calculations. Do this before worrying about backlash or other tuning.
But to check this scaling you need to have the motors on the machine. That may be your next step.
"giving this up". What! You've been at it less than what, two months. You've come this far you should keep going.
So far everything looks as expected but you can tell something is wrong. The part is nearly 2" long but the Z axis motor only rotates maybe once as it traverses.
Somewhere there should be a setting for configuring the gear ratio etc that says the motor has to turn so far to move a given distance.
I also recall something about handling backlash and various offsets that I need to look into.
I will admit, I'm still vacillating between giving this up (it's way more work/learning than I had counted on) and plowing on.
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But to check this scaling you need to have the motors on the machine. That may be your next step.
Thanks Hugh. You read my mind.
Found an XML file to configure Mach3 for the Sherline Lathe. That improved things regarding the motors but the step and direction pins were reversed for some reason.
Although improved, I know it's not right and, as Hugh mentioned, it's time to tune the motors on the machine itself.
1st Pic: Shows the 'stock' lathe and the various pieces to convert to CNC.
2nd Pic: Shows the lathe disassembled.
3rd Pic: Show the lathe assembled with stepper motors mounted.
I had to drill two holes in the end of the lathe bed to mount the motor. The cross-slide had already been drilled/tapped for its motor by Sherline.
I noted that the X and Y axes on the mill were also already drilled/tapped but the Z is not.
To drill the two holes was problematic. I ended up mounting the bed across the carriage of my 'big' lathe. With a bit of shimming and clamping I was able to drill the two holes.
Sorry, no pic. (It was a very ugly setup anyway...but it did the job.)
Soon I'll wire up the motors and play with the Mach3 jog functions.
Having a little trouble with CamBam to sketch a profile for a bowling pin.
I need a spline but every time I try I can't get the control points right. If I enter say 3 points, I'll see a dozen or more in the collection list (where you enter the exact coordinates).
Nor have I been able to import a DXF drawing and work with that. I haven't figured out how to delete everything except the profile I want.
Is there a 'trim' function in CamBam where you can lop off bits of drawing?
Instead of the bowling pin I'll try the spigot first. That's after I tune the motors, cut air, cry in my pillow, and pray to the machining gods.
You may notice the handwheels on the motor. Oddly enough, one slipped right on but the other is a struggle. A little reaming should do the trick.
Not that they are strictly needed but I think may be useful.
One of my better days for which I'm celebrating with a 'Stinking Hoppie'.
(Only the reason for celebrating changes...the Stinking Hoppie is a periodic occurrence even if the only reason to celebrate is "It's 5 o'clock!.)
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Is there a 'trim' function in CamBam where you can lop off bits of drawing?
Select the bits you don't want and hit delete.
To trim intersecting lines select the lines, invoke "break on intersections" ctl-B, then delete the unwanted parts.
It's not necessary to delete unused parts as long as the parts you want are correct. Only items selected in a Mop are used.
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Thanks Kirk.
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:cartwheel:
Got the motors wired up.
Did a little jogging to check things out then ran my spigot demo program.
So I've got a system 'working'. Now to tune the motors, double-check various settings, and do some testing.
https://www.youtube.com/watch?v=uNJROUiHkvg
[EDIT] The hand wheels will be removed. The Z axis one is barely on which is why it's wobbling.
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Can you do splines? I use a CAD system (linux based VariCAD) to draw the part in 2D, import DXF files into CamBam, then generate G-code for LinuxCNC. I tried this last night with a spline. The CAD system was able to generate a spline. That spline imported into CamBam well and was imported as a spline. Toolpaths were generated with CamBam OK, but the G-code output, using any of the post processors in CamBam broke the spline into arcs and lines. In a brief look I didn't see any post processor scheme or variables to output G-code for a spline. May not be the best forum to ask but I know there are smart people out there.
I was encouraged to find that LinuxCNC now recognizes G-code for splines:
G5 = Cubic Spline
G5.1 = Quadratic Spline
G5.2 = NURBS
So I think the problem is in getting G-code into CamBam and the post processor. Anyone out there able to cut splines?
Zee: I don't use CamBam for any drawing. I think a dedicated CAD system is better than CamBam. Thus I suggest you do drawings in a CAD then import into CamBam. I have had no trouble importing DXF into CamBam.
All the extraneous elements can be ignored in CamBam, just select the profile you want to cut. I have the best luck connection individual drawing elements into one polyline in CamBam before generating tool paths. To avoid confusion I generally delete unneeded drawing elements in my CAD before importing to CamBam.
Good progress.
Having a little trouble with CamBam to sketch a profile for a bowling pin.
I need a spline but every time I try I can't get the control points right. If I enter say 3 points, I'll see a dozen or more in the collection list (where you enter the exact coordinates).
Nor have I been able to import a DXF drawing and work with that. I haven't figured out how to delete everything except the profile I want.
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Thanks Hugh. Yes, I can (I think can) do splines.
I used CubifyDesign to CAD up a bowling ball which included a spline.
I then created a DXF and opened that in CamBam.
In CamBam (with Kirk's help on breaking intersections) I removed everything except the profile I wanted.
Then I created a rouging tool path and a finishing tool path.
Attached is a snap shot from CamBam. It shows the roughing tool path.
There are at least two issues I'm trying to figure out.
1) At the bottom of the bowling pin, left side, there's a small curve at the left of the spline. I suspect the cutter will rub against the bottom of the pin.
2) At the very top, at both ends, are what appears to be tool paths. I haven't investigated fully. It's possible I have remnants of the drawing, the profile isn't located properly to the Z axis, or I did something else wrong. I'll be trying it again. It may have something to do with when I transformed (moved) the drawing to line up with the axes.
In the meantime I'm working on a couple of other issues.
1) While my work bench is long enough for the manual machines, the machines don't fit if the stepper motors are attached. I have to do some re-arranging.
2) I realized the place where I was going to mount the power supplies, drivers, etc., while safe enough from swarf flying, would be subject to oil flying off the chuck/part. I'm considering mounting the hardware on a board and putting the board under the bench. Not sure how to do that yet.
This won't be the first part I'll attempt to cut under CNC. I'll probably use that spigot I created earlier.
But the bowling pin is my measure of success to complete this thread.
Thanks again everyone.
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Zee:
I was able to produce workable G-code which matched the spline well. However, CamBam broke the spline into a series of lines and arcs. Open the G-code file in a text editor. If there are only G0, G1, G2 & G3 commands yours is also a series of lines and arcs. Check and let me know.
Thanks.
Thanks Hugh. Yes, I can (I think can) do splines.
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I was able to produce workable G-code which matched the spline well. However, CamBam broke the spline into a series of lines and arcs. Open the G-code file in a text editor. If there are only G0, G1, G2 & G3 commands yours is also a series of lines and arcs. Check and let me know.
Thanks Hugh. Yes, I can (I think can) do splines.
The g-code output only shows G0, G1, G2, and G3. So just lines and arcs.
My comment about doing splines was in CAD.
Some progress in CamBam. It did turn out there were a couple remnants of the drawing that needed to be deleted.
However, I'm still left with 2 (so far identified) issues...
1) I can't seem to place the profile at the exact location I need. Perhaps it's related to 'snap-to-grid'. (1st attachment).
2) More troublesome is when I looked at CamBam's point list, all the dimensions appear twice as large as the dimensions in the CAD drawing. [EDIT: Appears to be because I had scaled the drawing in CAD by 2X. If I don't do that then the dimensions appear (more) correct).
P.S. It was indeed the 'snap-to-grid'. But I'm still wondering how I can move (transform) the profile to an exact position rather than eye-balling it. (2nd attachment).
It's still off. I see two X positions, -.0302 and -.0305. I wouldn't think I'd see any negative position and I don't know why those two differ by 3thou.
I suspect some kind of rounding error in the calculations used to create the g-code.
Much more yet to learn. I don't understand how the g-code position relate to the machine. It seems to me, wherever I place 0, the machine is going to move to the right.
That's fine if 0 is at the far left but that doesn't seem right to me. I was thinking that once I have faced the stock, I would be touching (and zeroing) on the face.
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For positioning I suggest you look at the edit/transform/align function. It will move all of the selected item according to you choices in the box. For a lathe profile you want X-Right Y-top. This puts everything left of the Y axis and below the X axis.
I use the alignment tool on essentially every part.
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For positioning I suggest you look at the edit/transform/align function. It will move all of the selected item according to you choices in the box. For a lathe profile you want X-Right Y-top. This puts everything left of the Y axis and below the X axis.
I use the alignment tool on essentially every part.
Thanks Kirk. That seemed to do the trick (at least for getting the profile in the right position).
I understand the 'X to the right' and 'Y to the top'.
I don't understand your comment about 'everything left of the Y axis and below the X axis'. I see the profile to the RIGHT of the Y axis and below the X axis.
See attachment. Is that what you expect? (This just shows the roughing tool paths.)
BTW After inserting the profile, I select 'Machining->Lathe' and then in the parameter block, I select the Work Plane as XZ.
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Align to the other side of Y axis.
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Align to the other side of Y axis.
I don't understand.
Attached is an example from CamBam documentation. Hopefully it's readable.
I don't see a difference between what they did and what I did.
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Normal lathe practice is to set Z0 to the end of stock at the tailstock end. So cutting is always in the -Z direction and Z g-code coords are all negative. But if this works for you have at it. All your setup does is displace all the Z coords. But you'll find it easier to actually set Z0 by touching the free end of the stock.
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Normal lathe practice is to set Z0 to the end of stock at the tailstock end. So cutting is always in the -Z direction and Z g-code coords are all negative. But if this works for you have at it. All your setup does is displace all the Z coords. But you'll find it easier to actually set Z0 by touching the free end of the stock.
Thanks! Touching off the stock was what I was thinking I needed to do but the g-code didn't make sense. Started a post about it but I was too confused to make the text understandable.
Thanks again!
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Well well. Success of sorts. Failure of sorts.
Now there are many many things wrong with this picture...
1) Yes, the stock is sticking way too far out. This is only a test. ;D
2) Depth of cut is too deep.
3) Part got pushed into the chuck. (Too deep a cut.)
4) Pulled the cutter out of its holder (see how it's angled?).
5) X at 0 was set along the X axis but it looks like it thinks it was nearly a half inch away.
6) Related to '5', it seems it thinks the raw stock had a greater diameter. Many cuts in air before it met metal. That is, the number of passes in Z seemed much more in Mach3 than in CamBam.
While running I heard a horrible high pitched scream. Happened only once while rapid moving back to home. No idea what that is but may be related to the motor tuning I did. I have no idea what the proper settings should be. It's supposed to be trial and error but I don't have a good idea of what I'm shooting for. At times I changed settings but it didn't seem to change operation.
Prior to this run, the X axis had gotten loose from the stepper motor. A preload nut is used to attach the lead screw to the motor's coupler. The nut was supposed to screw onto the lead screw but didn't. I found one in the mill CNC kit that fit. (Which means I need a replacement before I convert the mill.) A 4-40 goes through the coupler into the lead screw. I don't have a lot of confidence in that setup.
In any case, nothing broke, nothing caught fire, and I didn't hurt myself.
I call it success.
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Sure that scream wasn't a shop elf caught in the works? :o
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Sure that scream wasn't a shop elf caught in the works? :o
Wishful thinking.
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Hi Zee
The scream was probably one of your motors stalling, did you notice either one of the axis stop moving when this happened?
Have you checked that your step value is correct? if you command 1" of travel is that what you get?
Not sure how you set your x tool offset, on our lathe at work you manually (with the jog) take a fuzz off the OD of the stock and with out moving the tool in X, you mic the part and enter the value into the control. I have never done this in MACH but some how the control needs to know where the tool is.
Might be a good idea to set up an indicator and issue some commands in MDI and make sure that it repeats back to 0 in both X and Z (checking for missed steps) assuming that your step values are correct?
Dave
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Dave has it correct! Once the diameter is read and set in the DRO, both CAM and Mach need to use diameter mode. I think in Mach3 it's a Pots&Pins setting.
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The scream was probably one of your motors stalling, did you notice either one of the axis stop moving when this happened?
That's what I had thought too. It was a long scream but I didn't notice anything being off position as the process continued.
Have you checked that your step value is correct? if you command 1" of travel is that what you get?
Yes. I checked both X and Y. I do need to revisit that but I was within a few thou.
Not sure how you set your x tool offset, on our lathe at work you manually (with the jog) take a fuzz off the OD of the stock and with out moving the tool in X, you mic the part and enter the value into the control. I have never done this in MACH but some how the control needs to know where the tool is.
I used the jog function to face the stock. Then I jogged to its center and zeroed home. I was probably off a bit in X but not enough to be a problem. I'm sure Z was right but my placement of X home needs looking at.
Might be a good idea to set up an indicator and issue some commands in MDI and make sure that it repeats back to 0 in both X and Z (checking for missed steps) assuming that your step values are correct?
Did. But I should certainly do more checking.
I need to review the g-code again and verify the various movements. My suspicion is I probably didn't set (or I incorrectly set) some parameters.
Thanks Dave.
Feeling too good right now to pursue further until tomorrow. My celebratory drink(ing) means the machines stay shut down tonight.
Just saw your post Kirk. I do need to look into that. I'm not sure how 'diameter mode' changes things. My thought was g-code is g-code. If I say move G0 X1.0 Y1.0...it will move to position 1.0,1.0 from home. Are the positions given in the g-code modified by such parameters?
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Yes, the X words are just numbers that can indicate distance from centerline (radius mode) or twice that (diameter mode).
So CAM and control need to be in agreement.
My advice to you is to cut air for a while until you think it looks correct.
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The scream happening during a rapid is a sign of the motor stalling - likely due to
1) being asked to accelerate too quickly.
2) overall top speed is to high and the motor runs out of chooch at the top speed due to way and screw friction.
My bet would be on a combination of both, mostly 1 and a little of 2. They can be hard to separate as the machine is only so long so if you have a really gradual acceleration you may not achieve the top speed - run out of runway so to speak.
A few different ways to tackle.
1) try adjusting the acceleration only - bring it down 20% and rapid the z back and forth. You can setup an indicator, set it to 0 and slowly move away (G1 Z something positive and reasonable feedrate F) and then Rapid back same amount (i.e. G0 Z0). Note that I have rapid only one way. A lot less likely to smash your indicator this way - if it looses steps it will fall short, where as rapiding both ways can result in random loss of steps and could loose more steps moving away than back (experience here...). Should always return to 0 regardless of any other scalling if you go out and back the same amount. Be sure to set the indicator to 0 just like when running a manual lathe - i.e. account for backlash - were only working one issue at a time here! Repeat with more or less acceleration so that you know what its capable of before stalling, then reduce by a good amount (my rule of thumb is 30%) to account for cutting loads etc. Do the same for X as you didn't mention which one screamed.
2) with the same setup above try adjusting the top speed until it stalls or is not repeatable.
Top speed and accelerations are not important to hobby machines so you can really dial both back and be much happier with a reliable, but slightly slower machine than one that will also be reliable, but only at quickly making scrap pieces and making you scream. :Doh:
Mike
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Hi Zee
I wasn't sure how much setup and verification you had done, sounds like you are close.
Dave
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:cartwheel:
Changed the feed rates, the roughing clearance plane, and depth of cut and then used a simplified part drawing.
Verified both CamBam and Mach3 were in 'radius' mode.
Still many many questions but I think I have a 'Hello World' system.
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Hey Zee
That looks like pretty good progress!
Dave
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... I think I have a 'Hello World' system.
Your software background is showing! Still got your copy of K&R?
Glad its starting to come together!
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Now shorten the tool holder stickout.
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Your software background is showing! Still got your copy of K&R?
Left it at work for the next poor soul. ;D Nearly memorized anyway.
Now shorten the tool holder stickout.
Hee hee. I was waiting for someone to notice. But yeah.
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Your software background is showing! Still got your copy of K&R?
Left it at work for the next poor soul. ;D Nearly memorized anyway.
Now shorten the tool holder stickout.
Hee hee. I was waiting for someone to notice. But yeah.
I wound up keeping my copy - had it since college, couldn't bear to leave it behind. Though I have not opened it since!
Now shorten the tool holder stickout.
Good point - though on Sherline scale, its only out an inch! Question - other than keeping it in tight for rigidity, is there a rule of thumb for how far the tool point is out from the toolpost is okay?
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If it's > radius of stock that's all you really need.
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If it's > radius of stock that's all you really need.
:ThumbsUp:
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Your software background is showing! Still got your copy of K&R?
Left it at work for the next poor soul. ;D Nearly memorized anyway.
I wound up keeping my copy - had it since college, couldn't bear to leave it behind. Though I have not opened it since!
Everything I did in school was in Pascal. I didn't learn C till I got out on my own. Picked up a copy of K&R and never looked back. C is still my favorite :)
Kim
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If you are going to be playing with aluminium and non ferrous then also change the insert of a VCGT as it will cut better and put less load on the machine so you can run higher feed or deeper cut. Same with the mill get a few aluminium specific cutters if you are going to be working that regularly.
Apart from that looks like you will soon have a set of pins :)
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Your software background is showing! Still got your copy of K&R?
Left it at work for the next poor soul. ;D Nearly memorized anyway.
I wound up keeping my copy - had it since college, couldn't bear to leave it behind. Though I have not opened it since!
Everything I did in school was in Pascal. I didn't learn C till I got out on my own. Picked up a copy of K&R and never looked back. C is still my favorite :)
I burnt mine when I retired >:D I have kept all three volumes of Ward and Mellor ;)
Jo
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If you are going to be playing with aluminium and non ferrous then also change the insert of a VCGT as it will cut better and put less load on the machine so you can run higher feed or deeper cut. Same with the mill get a few aluminium specific cutters if you are going to be working that regularly.
Thanks all.
Jason...How did you know to suggest changing to VCGT? The ones I have are VCMW (HSS) and VCMT (carbide).
I've been searching for information on inserts...how to identify, how to choose, etc. but am having difficulty finding something simple enough for me to understand.
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VC was easy enough just looking at the shape, it's the GT part that makes them suitable for ali etc. In fact they work well on steel and stainless too but that will wear the sharper edge slightly quicker. I tend to use 0.2mm tip radius but you may be better with 0.4 as it is a bit more forgiving until you get the hang of things.
The other advantage they have over the coated carbide that you have there is that the aluminium will be less likely to stick though I would suggest a dab of Kerosene or WD40 which will stop that and also improve finish
The chart I tend to use is in the MSC catalogue, this is the UK one and you want pages 390 & 391, don't spend too much ;)
https://edition.pagesuite.com/html5/reader/production/default.aspx?pubname=&pubid=9c3eabd2-e3ba-4a9f-8bd3-aa6475bd6e37&_ga=2.33452094.1270605157.1588173128-37005281.1586275050
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Thanks Jason!
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Went for the bowling pin.
All went well until the last finishing pass.
Then it got caught and yanked out of the chuck. Got a little dent in the ceiling. ::)
I suspect my X zero was slightly on the other side of the center axis so when it moved out, the part was in the way.
Maybe reduce the plunge cut depth as well.
I need to figure out how to get X at zero. Z is easy enough.
To get X at zero would it be to touch the stock, measure the stock, and move half diameter? Seems inaccurate.
Still...this is considerable progress for me.
I need to play with the lathe some more but I'm noodling on whether or not to move on with converting the mill.
This is the start of the first of two finishing passes.
https://www.youtube.com/watch?v=m6xBnCLySTQ
1st two pics show the roughing process.
Last pic shows the 'result'. You can see the damage due to getting pulled out of the chuck and the damage at top of pin where the cutter got hung up.
It's always the last cut, the last hole, the last operation...then blooey. ;D
But I'm still :cartwheel:
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Nice! Run off some more, add a ball bearing, and your elves can start bowling. Anyone have plans for a mini pin setter?
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Even without CNC that is a far amount of stick out for a small chuck so could have happened on any machine. Apart from that it's a big step in teh right direction.
Have a look at Dave's answer yesterday about using the jog functions in Mach3 to take a skim off some scrap then measure that and enter the valve in mach.
J
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For X0 do what Dave suggested. Turn the end of the stock using the jog function. Back off in the Z direction without changing the X used to turn. Measure diameter with a micrometer. Set X DRO to that value.
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Hi Zee
Not sure how CAM Bam works but maybe there is an issue with your lead in or lead out settings, or depth of cut, or not the correct insert for aluminum, or....
That is a pretty dicey setup, given how tiny the chuck jaws are, at what point in your finish pass did the part get pulled from the chuck?
I think as others have indicated before, the 4 jaw chuck will probably hold better.
One ideal that I had would be to drill and tap the end of your stock and use a bolt through the spindle to pull the stock tight against the back of the chuck; it would be pretty hard to rip it out then. :Lol:
Then that part could be waste as you part off the finished piece.
Looks like you are hiving fun,
Dave
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Thanks.
Chris: The shop elves can just juggle the pins.
Jason: Yes, still sticking out a bit. Not sure how I would do this different.
Kirk: Yep. Gotcha.
Crud...
For another test I chucked up a 6" length of 5/8 diameter aluminum along with a live center in the tailstock.
Sheesh!
I used a depth increment of just 0.003" and a cut feedrate of 8 (it was 5 in an earlier test but got the same results).
Looks like it was threading (horrible noise) and then everything smoothed out.
The pic is after 3 passes of doing that.
Part of the problem too is that the live center would loosen up.
I'm suspecting the cutter was pushing the part into the chuck slightly.
Certainly, when I tightened up the tailstock, the part was getting pushed into the chuck.
I couldn't tighten the chuck any further without bending the tommy bars.
Not sure what's going on here.
Just saw your post Dave. As you see above, I had trouble with that chuck again. The 4-jaw needs to be tried. What a pain though.
The part got pulled out at the beginning of the last finish pass, at the tip of the pin. I'm pretty sure my X0 was slightly off (past centerline) and the depth of cut too much. So the cutter was coming out in X and a little in -Z. Because the cutter was 'past' the centerline, it was taking too much of a cut as it move out in X and in -Z.
I'm going to wait on converting the mill until I have more success with the lathe.
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Seconding what the others said, with softer metals like ali and brass, tailstock use is very important unless the bar is small enough diameter to go all the way past the chuck jaws. The jaws are shallow enough that they can dig in and twist under a cut an inch or two out. One thing about cnc is you don't have the same feel for pressures on the cutter as working manually. Small machine, light cuts, proper support.
(Written before your latest post)
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Wow that is some pretty serious chatter!
Looks like your stock is getting pushed away from the center right from the get go.
That gets back to the incorrect cutting tool, feeds and speeds, depth of cut etc.
What is your chip load? are you just winging it, or do you know for sure? You may be pushing things much harder than you think.
Dave
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What is your chip load? are you just winging it, or do you know for sure? You may be pushing things much harder than you think.
Well I think you're touching on the exact thing. Yes...I'm winging it to some degree. I've dropped feedrates and depth of cut...to values I 'think' are pretty low. But I am flying somewhat in the dark in that I don't know what to expect or what is typical. So I'm experimenting (winging it).
It just seems odd that about 3" out from the chuck the cutting seemed fine. More than that (even with the live center on the tailstock) and things go awry.
Lots to learn and gain experience in.
My main goal right now is not to get discouraged. If I get discouraged then things will fly out the window.
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You have to remember that you are not dealing with a very rigid machine, a "very" sharp cutting tool and modest feed rates are in order.
Do the fingernail test on your insert (like checking if your knife is sharp) if it just glides across it is not sharp enough.
Before you go to much farther you probably need to order some proper inserts or, sharpen and hone a HSS tool.
If your insert has a large nose radius that even makes the chatter problem worse.
Hope this helps,
Dave
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Did you set the tool "diameter" in CB to match the tip radius of the insert?
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Thanks Dave and Kirk.
I had flipped the insert around to the 'never been used yet' end. (The bowling pin test apparently broke the one tip. ;D )
The radius is spec'd as 0.015" which is what I used as the tool diameter. Should it have been .03"?
Dave: When you say "If your insert has a large nose radius...", my problem is I don't know what 'large' is. (Same problem with 'small' and 'typical'. ;D ) Experience and you all will get me there.
I seriously doubt this has anything to do with it but I remember the program was calling for a 1000 rpm spindle speed. I was running closer to 2500.
Which reminds me...It hasn't happened yet but there's a real risk that one can start the system going and forget to turn on the spindle. Whew. So far.
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One other thought...
I had faced and center drilled the part in my big lathe before putting it into the Sherline (so I had something for the live center).
I didn't know how else to get the part mounted.
I doubt things would have been so far out of whack that it wouldn't transfer well enough. No?
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Zee:
Facing and center drilling in a larger lathe should be fine. But if you don't have a larger lathe you can use a steady rest. Mount the part in the chuck then adjust the steady rest near the chuck. Then move the steady towards the end of the stock. That should support the end so you can face and center drill. Finally remove the steady and install a live center. Bob's your Uncle.
Or, if the stock is rough, mount in the chuck and smooth a small portion near the chuck. Adjust the steady on the finished area. Then turn the stock around putting the finished section outboard. Move the steady to the smoothed section and continue as above.
Did this last week on the Sherline, worked well.
Good progress. Congratulations.
I had faced and center drilled the part in my big lathe before putting it into the Sherline (so I had something for the live center).
I didn't know how else to get the part mounted.
I doubt things would have been so far out of whack that it wouldn't transfer well enough. No?
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0.003" DOC is not ideal for the standard VCMT insert as they are not so keen on fine cuts as they are not a sharp, another reason for going over to the VCGT
0.008" feed is also a lot for such a small machine, try 0.002"
What is the full spec of your inserts as that will have the tip radius includes, see my chart link yesterday, You may have VCGT 0602004 where the last two digits are the tip radius in mm eg 0.4mm (15thou) though they may have the US coding rather than ISO. Not sure how CAMBAM handles it but F360 uses radius. I would class a large radius anything above 0.4mm in our useage, the larger the radius the more cutter engagement and that can increase chatter.
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The radius is spec'd as 0.015" which is what I used as the tool diameter. Should it have been .03"?
yes.
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Zee, one thing I noticed when looking back at your photos was the position of the stock in the chuck, it was about like the end of this ruler:
(https://i.postimg.cc/9MFGfmLb/IMG-7037.jpg)
This photo is also a good reference for the others here, showing the size of the jaws on the Sherline chuck. They are a LOT smaller than the ones on the larger lathes, and where that part is held gives only about 1/4" of length gripped for a long (at least 4.5 inches I am guessing) unsupported part in a soft metal - I'm surprised that it stayed in place as long as it did. Always better to run it all the way in to touch the face of the chuck for larger diameters, for smaller ones go at least to the back ends of the jaws, or even better back to the end of the spindle . The way you have it is like holding something in your fingertips rather than using your whole fist. At one point you mentioned having to use the other lathe to center drill for the live center - that should be a clue that the part is not held well since end drilling a shallow spot is putting the least amount of force on the part - if it is not stable for that, then it will not take cutting while turning securely. On these small chucks, go in as deep as the part will allow.
A second thing I was wondering about for CNC work on aluminum: depending on which alloy it is, ali has a tendancy to gall and leave a deposit on the cutting tip if there is no oil used, which makes the cutter longer and take off more metal than desired. How do you handle that in a CNC run? When working manually, if I see that happen I'll back off the cut temporarily, clean and re-add oil, then continue. With CNC is there a way to do that, or does it mean aborting the whole thing?
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Thanks all.
Hugh: Good idea. I do have a steady rest.
Jason: Here's the specs on the insert. I got them (along with holders) from LittleMachineShop.
Insert Carbide VCMT221, Relief : 7 degree, IC: 0.250 inch, Thickness: 0.125 inch, Hole: 0.110 inch, Top opening: 0.146 inch, Radius: 0.015 inch
I have 3 HSS inserts as well. Same specs.
Kirk: :facepalm: And of course the parameter says 'Tool Diameter'. So the tip is off by .015". That seems large. But I don't see how that explains things.
Chris: Not sure which picture but yes. If it was the bowling pin, the chuck end had not been faced so I didn't push it against the chuck. If it was the little spigot, I didn't have a longer piece at the time.
I use WD-40 when cutting aluminum but there are times if I don't spritz quickly enough I can get a little bit of aluminum welded to the cutter. I expect to babysit the machine while cutting and can spritz it occasionally.
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Yes, it was from the post with the bowling pin pictures and short video of it working. With Aluminum especially, but also brass and steel, getting the part as far as possible into the jaws on the Sherline chuck is very very important.One thing I have done sometimes is to chuck it as far as I can with the sawn end at the chuck, lightly spot drill the other end and set up the live center, then face the rim far enough so that the smooth end will extend in to smaller than 3/4", so that the part can fit against the chuck face solidly. When doing large arbors, I'll go further and take that new face along the length by 1/2", which lets the part be gripped by the entire jaw and also sit against the outer ends of the jaw. MUCH more solid grip that way - well worth the couple minutes to do.
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Success! :cartwheel: Of sorts. :facepalm:
So I went for it again. Despite having stock sticking too far out and not having the optimal cutter (I used an HSS insert this time)...I went for it.
I must admit though...the first attempt resulted in the part being grabbed and thrown out of the chuck. I was trying to jog to face and find home using MDI but must have gotten something wrong.
I re-chucked and tried again. This time eye-balling home. I was close.
I was pretty amazed at the finish I was getting during the normal turning.
It took about a an hour and half to complete. I was fairly conservative in feedrate and depth of cut. Used quite a bit of WD-40.
The bowling pin itself is 2.5" long with a little 1/8" extension. The cuts were taken at .005" and a feedrate of 3 ipm.
There's a little nipple on the top of the pin. Should easily be taken care of.
Will do a little sanding but now the issue is how to part it off from the parent stock. Once it's parted I don't know yet how to finish the bottom.
But I'm a happy guy. If you know the kind of day I had today...this is a huge win. (I was ready to throw in the towel when the part flew out.)
Main thing now is to learn how to jog better and find my home.
No...main thing is I'm a happy guy right now. :ThumbsUp:
Many many thanks to all of you that helped. I couldn't have done it without your support. Thank you!
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:whoohoo:
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I recon you should feel bowled over with that, looks good. Now to get the mill working.
regarding the long overhang I wonder if it would be worth tackling it in two goes setting the cuts in CAMBAM to only do the first 1/2" or so while you don't have the narrow bottom and then bring up a female ctr in the tailstock before running a second set of cuts from 1/2" to the bottom.
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That would work as long as the stock will fit through the chuck and you can accurately re-establish Z0. I doubt the finish would be as nice as I'd expect some degree of mismatch between the two halves.
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That would work as long as the stock will fit through the chuck and you can accurately re-establish Z0. I doubt the finish would be as nice as I'd expect some degree of mismatch between the two halves.
I read his post to suggest one chucking, but to do the cuts at the outer half first, so there was not a narrow section near the base when cutting at the outer end. Would that help?
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I was thinking of leaving it all sticking out, still not ideal but at least it will not have that narrow waist that is more likely to flex than the full stock diameter.
Also don't really see the need to have that narrow waist near the chuck, better to just round the bottom corner and leave a decent diameter and follow up with a parting off cut.
EDIt Chris got it
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Thanks all.
Yeah, it's not a great example with the stock so far out of the chuck.
A bowling pin is something I had in my mind from years and years ago (when all I could do was dream of machining much less CNC).
I couldn't get it out of my mind. Ah well.
Chris mentioned a miniature pin setter and I must admit I had an idea for a miniature bowling alley several years ago.
Getting pins up to the shark switch, the sweep, and lowering/raising the pin table is 'easy' enough. Distributing the pins into the pin table is the challenge.
Also don't really see the need to have that narrow waist near the chuck, better to just round the bottom corner and leave a decent diameter and follow up with a parting off cut.
The only reason I did that was to make parting a little easier. I've always struggled with parting solid material.
The stock is 1" diameter. The base of the pin is about 3/8" and the widest part of the body is about .8".
With the little waist, I can bring the parting tool up to touch off the bottom of the bowling pin.
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Did a little sanding and then parted.
For parting I didn't use CNC. I don't know the jog system well enough and was a bit worried after my disaster yesterday.
So I unplugged the motors and used a handwheel on the back of the motors.
Then I used a dremel to take off the nipple on the bottom.
The finish could be better. Something else I need to improve.
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I suggest nine-pin pins for easy of turning. :Lol:
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I'm calling this done until I get the mill converted to CNC (which may be a while).
To recap...
I wanted to have a go at CNC but didn't want to modify my lathe and mill. So I got a Sherline lathe and mill and converted the lathe.
I chose a bowling pin as my test. It's a poor choice as it required the stock to stick too far out but I'd had this dream for years before I knew anything about machining.
Attached picture shows the control board:
1) 48V supply for the motors
2) 5V supply for the motion control board
3) ESS Smoothstepper motion control board
4) Gecko G540 stepper motor driver
5) Mains switch
The emergency stop is next to the lathe.
I used CubifyDesign for CAD. I've used this for a number of years.
I used CamBam for CAM. I found this very difficult to learn but finally came across a video that allowed me to figure out how to generate toolpaths and g-code.
I used Mach3 for motion control. I found this also difficult but had had some familiarity with the controls from when I worked for a company making table-top robots.
I got licenses for all 3 programs.
I had wanted to provide step-by-step instructions in hopes that others would find this useful but it's just too much for me.
Thanks again to everyone who helped. I think I would have given up had it not been for the members on this forum being so helpful and supportive.
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I don't think the bowling pin was a bad choice, you did learn more because of it. Looking forward to the next step on this journey! :cheers:
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Took another run at making a maiden post for the spinning wheel I'm thinking about.
This was mainly about learning/experimenting with CamBam and Mach3.
It's supposed to have a threaded hole at either end...which I skipped for this experiment.
I used the wrong cutter too in that it interfered with the bigger bead.
I have a couple of questions.
1st picture shows the post during turning.
2nd picture shows the 'completed' post.
I had considered at least drilling the one end that has the live center (all I did was center drill). I don't think I would have tapped it prior to turning as the live center (I would expect) would damage the threads. I'm not sure how I would do the other end that was in the chuck. Ideas? Perhaps use a follower? The part is too thick to go through the headstock.
The bigger issue was the noise. See video. As the cut begins, there's a whole lot of noise (I assume chatter) which went away after some distance. The finish looked excellent though.
I noticed that as the part got turned down, the chattering would continue for slightly larger and larger distances.
The finish look great up until the very last finish cut (of two). Then it crapped up. (The rings you see was after applying some WD-40 before the next cut.)
Noise happened for every pass. This happened the other day as well on my first attempt.
.005 depth of cut and 3 ipm feedrate. It was slow. Took a little over an hour to complete.
What's the cause of the noise and what can I do? Spindle speed too high? (Dummy me didn't think to adjust it to see if it helped.) The spindle was running about 2200 rpm instead of the 1000 rpm that the feed/speed had said.
Thanks.
https://www.youtube.com/watch?v=Lb4BmWAChMw
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Chatter is resonance, so you could try varying both RPMs and feed rate. You should make only 1 finish pass as the second is likely just rubbing.
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What's the revs as can't tell how much you are cutting with just a feed rate.
Tool does not look to have much top rake which aluminium likes, is it cutting dry
Does CAMBAM not have a simulator that would show the tool cutting where it is not meant to?
That long extended ctr won't help with rigidity, same with tailstock extension, reduce it if you can and maybe even think about using a solid tool post which will not put the tool so far over to the left and therefore the carrage won't go so far right to hit the tailstock base.
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I don't know the capabilities of a Sherline, but based on that video, I would be inclined to say rpm too high and feed too slow.
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Thanks all.
I'll try varying the rpm. I think the feedrate was a tad slow but perhaps not by much. Need to buy some more material.
What's the revs as can't tell how much you are cutting with just a feed rate.
Around 2200. I'm thinking it should have been half that. (I don't have a means to measure yet.)
Tool does not look to have much top rake which aluminium likes, is it cutting dry
HSS tool. Doesn't look like there's any rake. I need to go shopping.
Does CAMBAM not have a simulator that would show the tool cutting where it is not meant to?
CamBam shows the tool paths but only the tip. I don't believe there's a way to model the shape of the cutter.
I wasn't surprised the cutter interfered on the sides.
That long extended ctr won't help with rigidity, same with tailstock extension, reduce it if you can and maybe even think about using a solid tool post which will not put the tool so far over to the left and therefore the carrage won't go so far right to hit the tailstock base.
I think the tool post can be moved to the Z+ side of the carriage. Have to check if the Z- side will hit the chuck before the cutter.
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Zee, which alloy of aluminum are you using? Some machine better than others.
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Zee, which alloy of aluminum are you using? Some machine better than others.
6061 aluminum
My selection of material is small.
6061 aluminum
360 Brass
303 Stainless
I haven't done much with steel. Some 12L14 and some cold rolled that I don't remember (I think 1018).
I welcome suggestions for machinable metals.
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Those are all good ones.
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Cast iron sarf is dirty but it machines nicely. 1144 stressproof is good.
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Thanks.
I've done next to nothing with cast iron. I should try the 1144. I saw that Chris used it as well. How is it for rusting?
Next silly stupid fun question...
Learning CNC is part of my goal to make a model of a spinning wheel for my daughter. So I've been experimenting with parts where CNC is beneficial, if not necessary.
First attachment is a finial. It would be made of brass and serves as a 4-40 bolt. The finial itself is about 3/8" long and just under 1/4" diameter. The nut is 1/4" and 3/32" thick.
I don't know of a tool that can be bought and used to cut that curve between the finial top and the nut.
Second attachment shows an HSS cutter that I'm thinking of making (an adventure for me in and of itself).
Thoughts and suggestions are welcome.
The cutter has a 1/16" nose to it. It doesn't necessarily have to be exact. The goal is to make 6 identical finials.
I'm still considering converting the mill to CNC. I'm seeing less and less reason not to and more and more reason to go ahead. Particularly as it would support engraving which might be pretty cool.
I came across a software tool that wraps text (generated in CamBam) around a round object (for example, a pen). I haven't seen too much about it though.
[EDIT]: I would take hex stock and make the thread first. Then put that into a holder for the chuck to do the CNC stuff. I'm wondering if I need to slit the holder and let the chuck act partially as a vise. But I'm thinking that just threading it is good enough.
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The 1144 is not stainless, it will develop a light surface rust if it gets wet and not oiled. Much less so than the 12L14 alloy. The only time I use 1144 is for parts where I am cutting non symmetrical parts from a larger bar, since it doesn't warp from stresses introduced while they roll it out. It is harder than 303, which I prefer for everyday parts.
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You can get tools with a 1/16" or smaller round end, I've got inserts 1mm wide with a half round end and others that are "lollypop" shape with a 2mm dia end on a thinner body which although a bit larger are cheaper than the 1mm holders available with 6mm shank and they also make a parting/grooving insert at the same width.
The other option is to use your CNC mill to cut a form tool from ground flat stock and simply use that to cut the shape if the sherline is upto it
My tactic on that part would be CNC the "head", over to the mill to form the hex then back to mill to take to bolt dia and part off, then probably best to manually thread. Not sure I would want to try it the other way round by doing the thread first and then screwing into a holder to do hex and shape as 4-40 may be a bit weak unless you did very fine cuts.
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Thanks Chris.
Thanks Jason.
Jason...any chance of some pictures or references to the cutters you mention?
BTW the shanks I have are 3/8" square. Although it looks like 1/2" and 1/4" can fit as well.
Also, I had planned to start with hex stock.
Yes, I think the 4-40 may twist off. The original design called for something bigger which might have been okay.
Not sure I can properly hold the part to do the threading. The 'nut' is 3/32 thick. I'll think some more on that.
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The Mini-radius cutters are the smaller ones I mention
http://niko-nikcole.com/wp-content/uploads/sites/6398/2018/03/Minisystems_web_v1d.pdf
And the 2mm inserts can be had from anywhere
https://www.shop-apt.co.uk/grooving-inserts-mgmn-style/mrmn-200-m-up25-copy-turning-insert-2mm-wide-1mm-radius-forming-pvd-coated-general-use.html
As can the holders
https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Lathe-Turning-Tools-Indexable/ARC-Indexable-Turning-Tools/ARC-MGEH-Parting-Grooving-Tool-Holders
Another option on your parts subject to teh diameter of teh "neck" would be to drill and tap 4-40 and part off. Then make a holder by tapping some rod, cut off a socket head screw and screw the shank into the holder ( stronger than cutting a make thread) and screw the embryo nut onto that and then CNC turn. that way you can either use as nuts or loctite in some threaded rod
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Thanks very much Jason! :ThumbsUp:
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In converting the machines to CNC, a thought that keeps popping in my head is 'locking the gibs'.
I'm very used to locking down axes that won't move during a cut. What are the 'rules' or 'best practice' when it comes to CNC?
P.S. I lied. I'm not used to locking down axes but I keep getting better at remembering.
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Zee:
Can you tap the part itself and use a set screw to extend a male thread out the end? I'd find it easier to tap the part than thread a 4-40 round. I'd tap the stock, put a piece in the chuck and tap it, then connect the two with a set screw. Steel set screw should be ok for further machining?
Hugh
Yes, I think the 4-40 may twist off. The original design called for something bigger which might have been okay.
Not sure I can properly hold the part to do the threading. The 'nut' is 3/32 thick. I'll think some more on that.
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Zee:
Can you tap the part itself and use a set screw to extend a male thread out the end? I'd find it easier to tap the part than thread a 4-40 round. I'd tap the stock, put a piece in the chuck and tap it, then connect the two with a set screw. Steel set screw should be ok for further machining?
Hugh
Yes, I think the 4-40 may twist off. The original design called for something bigger which might have been okay.
Not sure I can properly hold the part to do the threading. The 'nut' is 3/32 thick. I'll think some more on that.
Thanks Hugh. That was the original idea for this part. But I realized it had to work like a bolt to hold a horizontal piece on top of a post.
For now this is simply more of a concept. I'm more interested in learning how to shape the finial.
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No locking of axes in CNC. The steppers lock movement when not needed.
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Would that apply to non ball screw machines that may still have play in the nut/leadscrew like Zee has? Though you would have to work fast to keep up with the machine to unlock then lock an axis as it put on a cut.
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The only CNC machines that even have locks are converted manual machines. Steppers do the job; just try to turn the screw yourself when stopped in M01.
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Isn't that what Zee has? as I mentioned a conversion that does not have ball screws could have backlash even if the screw won't turn things could move.
would have thought that if there was movement when say boring holes on the mill you could set a slow plunge rate to give time to lock an axis and same with retract but would need to be careful it did not want to move to the next position before things were unlocked. Or if using conversational you could move to position then lock and run the spot, drill, bore etc with position locked if still on leadscrew and nuts.
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Jason:
You could use table locks between moves. You could even put in a pause between moves so the machine wouldn't try to move before you released the lock. However, this isn't really practical. But you are right, the table can move through the backlash when the lead screw is fixed, here by the stepper.
In my opinion, if the backlash is large enough to cause serious problems then the backlash needs to be addressed. Most CNC machines have ball screws with very little backlash. More than 2 or 3 thousands and, in my opinion, adjustments should be made. The controller I use (LinuxCNC) can be set to adjust out a few thousands backlash. The controller just throws in the correct number of steps when reversing to cancel the backlash. ("adjust out" assumes the backlash is the same through the travel.)
Small backlash also allows climb cutting, smoother finish and better tool life. If there is much backlash the tool is pulled forward through the backlash which causes all kinds of trouble if the backlash is "large".
I have a converted knee mill and I can't remember using a table lock after I converted it. But when setting tools I approach the final set point from only one direction. Important or habit, don't know?
Thanks.
Hugh
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Interesting discussion. Thanks. BTW I don't have ball screws. I believe they are available but didn't want to go through the expense until I'd learned enough.
I had trouble finding a suitable cutter and holder for the finial. If I knew I would be doing this a lot then I'd spend more time (and money) on it.
Instead, I found an HSS boring bar that only needed the tip rounding. Not a great job but useful.
You can see that the top of the finial is not round but has a small flat. I have some questions regarding finding the home position.
As an example, the tool is about .08" in diameter. This means the virtual tip is .04" in from the edges.
If I home in Z (or X) by touching off the stock, the virtual tip is .04" away.
It just seems to me that this is the source of the error.
Is this offset automatically taken care? Do I need to make some adjustment?
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That would probably depend on CAM Bam. On the machine that I run at work (Fagor Control) you define the tool shape and how it is referenced. It could be left edge right edge or center. Also the rotation of the tool is defined after all you could be cutting on the back side of the part with the spindle running in reverse, (probably not on the Sherline with the threaded on chuck though). ;D
This is a conversational control so all the programming is done at the machine, no CAM.
Dave
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On the machine that I run at work (Fagor Control) you define the tool shape and how it is referenced. It could be left edge right edge or center.
Thanks Dave. That tickles a memory. I'll check into it.
So far I'm fairly pleased with how things are going. I'm still not sure whether or when I'll convert the mill.
All the parts I'm thinking about are simple and, I think, more easily done manually.
On the other hand, converting the mill will facilitate engraving and that's something I'm interested in.
P.S. Dave...I don't think CamBam provides defining the tool shape for the lathe. It may be that you can create tools, along with their specification, and then be able to select one out of the set.
But so far I think that just amounts to defining the tool tip radius.
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I don't know your soft wear . to get the right end shape cutter compensation has to be made .modern machines with conversational controls make it easy tool file has the tool data and the programming system does the work.
older machines with more basic controls the cutter compensation g codes can be used .the tool does not cut at the
point so the tool path has to compensate.I frogman machines for a long time manually with g codes and a big part was using the controls cutter compensation G41 G42 on milling profiles on milling machines g41 42 though to 49
but one control needed I & j with the g41 to start correctly others needed g38 I& J at each change of direction.
3 d shaping i had to work out manually .
I would like to think the soft wear you are using will do the work for you .
I did program some older machines more nc no computer power. tool compensation had to be worked out manually each line g and m codes.even screw cutting was a separate line for each pass no soft wear or a computer that could do that or the ones that the company had were not much use .
John
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Zee:
It's been awhile, but I think CamBam automatically compensates for tool tip radius. If I remember correctly I've just touched off for Z and X using the tool as it touches the surface. Then specify the tool radius (or is it diamater?) in CamBam and the code comes out correctly. CamBam adjusts the G-code rather than using actual tool compensation. Thus, it should run on any controller. It does not take into account the shape of the tool, other than tip radius, so be careful the edge of the tool doesn't cut stuff you want to keep.
You can check all this. Pull up a DXF of the part and track through the G-code drawing lines as the tool would move according to the G-code. If the lines come just to a tool tip radius of the part you're golden. If not, track down why. This is a good way to see why there's a flat on the top. It's likewise a great way to learn some simple G-code commands.
This is the cheap man's CNC simulation, a very manual process. If you find a decent lathe simulation program for cheap please let me know, I have yet to find one.
Thanks.
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Going by the way F360 does it if touching off the side and end of the tool you need compensation set to "tangental" as the edge of the work is tangental to the circle formed by the tip. There are other option such as centre of tip so you would need to make allowance for that when touching off of tip radius. On F360 the image of teh insert comes up and you can see the setting point move as you click the various options. Also allows you to set the tool at an angle which is useful if the back edge is going to rub.
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Thanks all.
I've been doing some googling to try and understand this but I'm having a bit of trouble. In part because I'm just not that familiar with all the terminology.
Attached is a pic of what I'm trying to figure out.
The gray and yellow line is the profile I want to cut (i.e. the finial).
The red represents the tool tip (I'm showing 3 locations).
The tool tip is 1/16" diameter.
Consider the right-most tool tip (and assume its left straight edge is up against the yellow line)...
The home position is at X = 0 and Z = tip of finial plus radius of tool tip.
In that case the very tip of the finial won't get cut. Right?
But also note that the left-most tool tip should cut the 'neck' properly.
Then consider the middle tool tip. Here the actual tip is past the axis.
The home position is at X = -1/32 and Z = (as before) tip of finial plus radius of tool tip.
While that should take care of cutting the very tip of the finial...I'm not sure that the profile will be cut correctly.
And, I suspect the 'neck' may get cut too deep.
As for CamBam...you cannot define the shape of the tool, only its radius (actually diameter).
You can specify a 'Lathe Tool Radius Offset' but I don't know enough about it yet.
When I get a chance I also try the CamBam forum.
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Zee
The radius is sufficient .
your program soft wear produces a tool path to give the proper shape.
an example would be.you have set z0 by touching on the end with the side of the tool i don't know how you do it on your machine but x is set to turn a dia may be by touching known dia so x dia is set .
the first line for a tool path using g codes would be a facing cut so goo
z0x13.(for a 10 dia bar
go1 x-.8 (facing cut it has to go -.8 for a .4 radius tip so the edge cutting gets to the centre ) then
z2.
g0x7.2
g01z0
g03x10.z-1.4i-1.4 (to give a 1mm radius on the corner)
go1z-10.
hope you can follow a g code programmed tool path
so your program has to out put a program for your machine so the tool path so the sizes on the finished part
will be the wanted sizes and shape
side of the tool is set at z0 and the end of the tool is the x dia
John
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Thanks John.
I had faced the part using the jog controls. (CamBam doesn't support facing but it's easy enough to do. Can also use MDI.)
Then I found/set home pretty much as you described.
Then I ran the program.
In the attachment, the red represents two positions of the tool tip.
The right-most one is at the home position. (left side of tool is Z0 and tip of tool is at X0).
It seems to me the tip of the part will not see the cutter.
If I define X home such that the tool tip is further past the center line (i.e. X = -.03125 then I worry that the neck (at the left-most image of the tool tip) will be wrong.
BTW The lathe tool radius offset was set to true which places the 'virtual tool tip' for a right hand cut to the left and above (in my picture) the center of the circle of the physical tool tip.
If the lathe tool radius offset had been set to false then the virtual tool tip would be the center of the circle of the physical tool tip. I don't know if that makes a difference.
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The tip of the tool should be able to go beyond the centre line so that all of it's curved end is used for cutting so in your case it will move approx 0.031" forwards and maybe 0.010" towards the chuck when it is cutting the very end of the workpiece. This is just the same as any ball nosed milling cutter would do it.
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Hi
The tool tip needs to go past the centre so that side of the tool is at z0 x forward so that part of the tool at the side is at the centre .so it cuts to the centre .at the and of the program the tool can only go to the end face where
the side of the tool touches that face.just like an end mill would if it was cutting out a profile.
I found it was good to have a slightly larger radius than the tool so the tool has to move to produce the shape.
just a few thou can be enough tools don't like going into a corner were it does not move.
if you define the x home so it is past the centre then your x dia will also be wrong the tip or front of the tool
must be set to produce the correct dia.the program must go past the centre compensating for the radius then
when it goes along the shape the dia will be correct .when it gets to the end at that radius it has to fit into the corner if it thinks it won't fit it might only go as far as it think it can so the final dia may not be what you want.
John
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Zee:
Did you study either the CamBam cut lines in CamBam or plot the G-code moves on a DXF form? Those (particularly a plot of the G-code commands) will tell what is really going on. Can you show a plot of the cuts from CamBam?
If it's not cutting to X=0 due to the tool radius, just extend the cut line a tool radius past X=0. But I do believe it cuts to the center.
FYI, I was taught to make a cut radius a little larger than the tool radius. If they are the same it takes a very large bite when going into that cut. For example think of taking a 0.005" finish cut. The cut is very light moving over the profile. But when it drops into a radius the same as the tool, it will take a full bite over the entire arc at once. That's a lot more material and can give poor finish. Your tool diameter is 0.0625 (1/16") so make the tight arc at the bottom maybe 0.070" or 0.075" diam. I'd never have thought of this until it was explained to me. The same applies to milling.
Thanks.
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If you have a rough cut and leave a finish cut when the radius of the tool is the same as the finish size the rough cut won't fit so it may leave more than a finish depth of cut for the finish cut when it gets to that position and
can get lost if the radius means no movement for that radius will depend on the soft wear as to what it does under those conditions .As Hugh Currin suggested if you can look at a plot of the g-code commands have a look at what it is doing.
John
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With some CNC controls and software you will get an err message if you try to cut a radius the same size as your cutter. Most of the time you can avoid this my using a cutter with a smaller radius than any corners you need to do, but can cause problems when you need radiuses smaller than 1/8". Spent many an hour explaining to designers that just because they can draw it doesn't mean we can make it, and asking does that radius have to be that tight or did you just draw it that way because it looked pretty?
Gerald.
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You can declare the tool radius a tenth smaller than the radius to cut to avoid math errors in CAM.
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But is that likely to stop the chatter when a tool goes into a radius the same as the cutter? and what doe sit do to the O/A size of the part
Since I have got the CNC I have taken to drawing up any parts I want to make on it with a larger fillet radius than the tool I think I'm likely to use. eg where I may have specified a 3mm radius as its a reasonable round number I now find I go for 3.25 or 3.5 if I'm thinking of using a 6mm cutter, No doubt you would be thinking of drawing 1/16, 1//8" radius but probably need to think about drawing 0.035 or 0.070" radius as it is mostly easier to alter the part and use a standard cutter
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what ever is on the program the tool will not like cutting the full radius the same or very near the radius of the cutting tool by making the radius bigger than the tool like you suggest is good .you could always come back with a smaller tool and just finish that bit with a separate cut.
when programming old machine which old controls using cutter compensation a tangental radius had to be added
to internal corners for it to work the machine did not read ahead i would put a 5.5 rad for a 10mm end mill but any end mill 10mm dia that had been ground could be used as long as the radius was put in the offset.the bigger the difference from the radius the better they will cut.
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Very interesting discussion. Thanks for that.
I understand the issue regarding cutting the radius with a tool of the same radius.
Easy enough to make a change to the drawing.
I tried a couple of things today.
The first was to turn on the tool tip radius offset. That was a complete failure. Most of the tip of the part did not get cut and for some reason, neither was the side cut.
That's on the left side of attached picture. So forget that.
Then I turned tool tip radius offset off again but set the home position such that the tool tip Z was centered on the end of the part and the X was past the centerline by the radius of the tool tip.
Better but still off.
That's on the right side of the attached picture.
Not that shape of the part end that I wanted.
In any case, this seems to be about understanding where the virtual tool tip is, where the actual cutting edge is, and where home is defined.
When it comes to the virtual and actual tool tip...most of what I've come across has been about a left or right hand cutting tool.
In this case I'm using a tool that looks like a parting tool with its tip rounded over. No 'left' or 'right'. (Which I think is why I want the tool tip radius offset off.)
2nd attachment shows the tool paths.
Passes up to the lower green line are roughing passes.
The last green line is the finishing pass.
So where should home be? To the right of Y and along X? On Y and X? Past X for either Z?
But I don't know (yet) what the post processor does.
BTW CamBam generated two finishing passes (I believe someone mentioned it should be one.)
Could this be a mismatch between the roughing clearance profile and the depth of cut for the finish?
I really appreciate all the comments. Helps a lot.
I think I'm making progress. That's what counts.
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Hi Zee
when you set your xo front of the tool is on the centre line end of the tool will produce correct x dia you want
z 0 is still the end part is z-.these should remain the same what ever you are machining only adjust x togged correct x dia error.
then it is work on your part program to get the right part that you want.
the tool radius is on the approach side you are cutting from tail stock end to chuck just think of the radius on that side .
now with out cutter compensation you should get a tool path that will leave a little bit at the centre radius of the tool .then the overall dia should be correct ( x0 was set )the only error will be the radius on the part will have error ,The tool will cut at different points around the radius of the tip but the general shape should be there .
when you turn on cutter comp it should correct those errors by giving only slightly different path
so try plotting with out comp on see if you have the right shape don't change x0 or z0 that changes the position of the whole shape .whe that is right .try with comp on and see what the changes are to the tool path.
if that is not right you have to go back to see how the program starts and gets the compensation work .see if you can get the plot to look right.
John
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Thanks John. You gave me an idea.
I wrote a (very dirty) little program to plot the toolpaths and output the points so they were easier to analyze.
1st pic is a screen shot of the program.
The yellow crosshairs are the beginning of a cut. The length of a hair is the diameter of the tool tip.
Think of the crosshair as a circle representing the cutter.
The green lines are the axes.
Ignore the two crosshairs at the very top. They're a remnant of testing the drawing of the crosshair.
You can see that the cutter crosses the X axis.
With tool radius off I saw that the tool tip never crossed the X axis.
With tool radius on (as shown in the attachment), the tool tip cross the X axis at the end of the part.
I homed the cutter in X by moving the tool tip against the flat of the part.
The stock is 1/4" hex brass. So home was set to 0.125".
I homed the cutter in Z by moving the tool tip against the faced end of the part and setting it to 0.
2nd pic shows the result.
The left end was the very first attempt. The right end is the result of this attempt.
The diameter of the finial measured 0.246 (perhaps 0.245) which was pretty spot on according to my drawing.
You'll note the left end is significantly smaller. I don't know why. I don't care.
However, there's still a slight flat on the very end of the part (right side).
I think it's because of the cutter itself (and possibly an inaccurate Z home). The cutter was homemade and I don't think its tip is perfectly round.
But overall I think it worked. I certainly got a better understanding.
One thing that worries me is having the raw stock pushed into the chuck as cuts are made.
I don't think that happened this round (very light cuts) but I think contributed to the failure on my first attempt (left side).
3rd attachment is the g-code file.
4th attachment is the output of my little program...
1st column is whether the move is G0, G1, or G2.
2nd and 3rd column are the X and Z coordinates. You can see that X goes negative.
4th and 5th columns are the coordinates used to create the graph. This is after scaling but before applying offsets to keep the drawing from the edges.
Thanks everyone for your help. I learned a lot.
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Zee:
Now I'm quit confused. I can't find anywhere in CAMBAM to set "tool radius" on or off? I found "Lathe Tool Radius Offset" in the CAMBAM documentation related to post processors but can't see how to apply it. It doesn't seem to show up in any of the lathe posts. Where are you setting this?
I think CAMBAM outputs a tool path for the center of the tool, center of tip diameter. This is the same as it outputs the path for the center of the tool for milling. As long as the tool diameter is given to the controller this should work without any tool compensation.
Looking at the tool path plot on your previous post. I think this worked OK. If you take this path as the center of the tip diameter it starts cutting at the center of rotation. The top of the profile should be cut. It then follows the profile to the left as it should. It does look like it's not reaching the bottom of the cut on left side. It's like the tool is too large to get to the bottom. But this could be the way I'm seeing the drawing. If I'm seeing it correctly reduce the tool radius and see if it goes deeper. But the start of the cut at the far right should be OK.
You might try a lead in motion. This feeds the tool into the starting cut. Also, if you think the part may be slipping in the chuck you may not want to cut from the center. There's no relative motion at the center of rotation so cutting is like using a drill, takes some force. Starting the cut at the center of rotation could give a "large" cut to start. You could try taking a facing cut first to final size. Start from the OD and feed in to the center, like you would with a manual machine. Then run the profile cuts.
Starting past the center of rotation may be counter productive. This will put excess force on the part towards the chuck. If it tends to slip in the jaws this will make that worse. (yes, I did suggest this but after further thoughts I think it may be a bad idea.)
Good progress, congratulations.
With tool radius off I saw that the tool tip never crossed the X axis.
With tool radius on (as shown in the attachment), the tool tip cross the X axis at the end of the part.
I homed the cutter in X by moving the tool tip against the flat of the part.
The stock is 1/4" hex brass. So home was set to 0.125".
I homed the cutter in Z by moving the tool tip against the faced end of the part and setting it to 0.
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Thanks Hugh.
Now I'm quit confused. I can't find anywhere in CAMBAM to set "tool radius" on or off? I found "Lathe Tool Radius Offset" in the CAMBAM documentation related to post processors but can't see how to apply it. It doesn't seem to show up in any of the lathe posts. Where are you setting this?
Sorry about that. I meant Lathe Tool Radius Offset. It's in the System tab. Select the post processor (Mach3-Turn in this case) then scroll down in the lower pane. Same place where you set whether X mode is radius or not.
I think CAMBAM outputs a tool path for the center of the tool, center of tip diameter. This is the same as it outputs the path for the center of the tool for milling. As long as the tool diameter is given to the controller this should work without any tool compensation.
That was in part why I wrote my dirty little program. Seeing the tool paths in CamBam didn't tell me what effect the post processor had (if any). And, I couldn't tell by the plot if I was seeing the 'center' of the tool tip or the cutting edge. Keep in mind, that attachment showing the plot is my program, not CamBam.
Looking at the tool path plot on your previous post. I think this worked OK. If you take this path as the center of the tip diameter it starts cutting at the center of rotation. The top of the profile should be cut. It then follows the profile to the left as it should. It does look like it's not reaching the bottom of the cut on left side. It's like the tool is too large to get to the bottom. But this could be the way I'm seeing the drawing. If I'm seeing it correctly reduce the tool radius and see if it goes deeper. But the start of the cut at the far right should be OK.
I'm not sure I follow. It did not start cutting at the center of rotation. It started from just outside the surface of the stock, bringing the part to diameter. Then worked along the tip, then made the final roughing and finishing cut starting at axis of rotation. I think the reason you mentioned 'not reaching the bottom of the cut on the left side'...CamBam just shows the tool path and not the shape of the tool. In my program, the crosshair represents the shape of the tool. Just pretend it's a circle. (I had enlarged the part radius a bit so the cutter wasn't cutting along too much of its circumference.
You might try a lead in motion. This feeds the tool into the starting cut. I've seen references to 'lead in'. I don't know anything about yet or what it means.Also, if you think the part may be slipping in the chuck you may not want to cut from the center. There's no relative motion at the center of rotation so cutting is like using a drill, takes some force. Starting the cut at the center of rotation could give a "large" cut to start. You could try taking a facing cut first to final size. Start from the OD and feed in to the center, like you would with a manual machine. Then run the profile cuts.
If I understand you right, I think that's what was happening. That is, starting from OD, cutting right to left, and slowly moving towards axis of rotation. Or if you look at the plot from my program...start at the lower right. It moves left then starts over a litte closer to X.
Starting past the center of rotation may be counter productive. This will put excess force on the part towards the chuck. If it tends to slip in the jaws this will make that worse. (yes, I did suggest this but after further thoughts I think it may be a bad idea.)
It only goes past center of rotation during the last roughing cut and the finishing cut. By which time there is little part left. I think it was possible the part got pushed into the chuck on early attempts because the depth of cut was too large.
Good progress, congratulations.
Thanks!
With tool radius off I saw that the tool tip never crossed the X axis.
With tool radius on (as shown in the attachment), the tool tip cross the X axis at the end of the part.
I homed the cutter in X by moving the tool tip against the flat of the part.
The stock is 1/4" hex brass. So home was set to 0.125".
I homed the cutter in Z by moving the tool tip against the faced end of the part and setting it to 0.
After finding home I moved the cutter away from the part before starting the g-code program.
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it looks like you can see whats happening now .
the idea of a facing cut is what you would normally start a programme but as the roughing cuts have removed most of the metal as the program progresses that is not needed for the finish cut the tool going past the centre is because it is cutting at the side of the tool at this time not at the end.
moving in the chuck is problem from the force of the cut.on bigger industrial machines with big powfull hydraulic chucks it happens .machining harder tools steels even more likely turning whith a centre means as it moves the centre comes forward until thing get in the way the tool can come into the live centre or when there is not much room parts of the machine can bump.often using soft jaws they can be machined with a step ,the material has tone against something so it can not move .
good to see you can see whats happening now.
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Hugh
the calculations are done as from the centre of the tool radius but the tool is set to the edge either the side z0 or the front of the tool x when milling the x0 y0 are set in the centre of the tool.
hope that helps.
John
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Zee:
I was mostly going off your previous CamBam plot:
(http://www.modelenginemaker.com/index.php?action=dlattach;topic=9555.0;attach=114877;image)
Sorry about that. I meant Lathe Tool Radius Offset. It's in the System tab. Select the post processor (Mach3-Turn in this case) then scroll down in the lower pane. Same place where you set whether X mode is radius or not. No problem. I found it via your direction. I made up a small test part and had CamBam generate lathe code for it. I ran two versions, one with Lathe Tool Radius Offset true and one false. I couldn't see a difference in the tool paths. So, I compared the two *.nc files and found the only difference was the time stamp. Thus, this parameter doesn't seem to do anything, but I don't know what it is supposed to do? The description in CamBam documentation isn't clear to me. Can you explain what it's supposed to do?
I'm not sure I follow. It did not start cutting at the center of rotation. It started from just outside the surface of the stock, bringing the part to diameter. Then worked along the tip, then made the final roughing and finishing cut starting at axis of rotation. I think the reason you mentioned 'not reaching the bottom of the cut on the left side'...CamBam just shows the tool path and not the shape of the tool. In my program, the crosshair represents the shape of the tool. Just pretend it's a circle. (I had enlarged the part radius a bit so the cutter wasn't cutting along too much of its circumference. My bad, I'm not explaining things well. I was thinking of the final roughing and finishing cuts. They do cut at the center of rotation, but after the previous cuts it's taking little material. Although that depends on how much stock is left to cut on the right end. Looking at the CamBam plot above, the center of the tool radius, plotted points, do start at the center of rotation for the last rough and the finishing cuts. It should be cutting the whole profile.
In this plot again, it looks to me like the tool path doesn't reach the center of the circular profile on the left end. This is what I meant in my previous email. It's hard to see this in your plot as the profile itself isn't shown. If you increased this profile arc you've likely fixed this.
I've seen references to 'lead in'. I don't know anything about yet or what it means. This screen shot (attached) of CamBam for my trial part shows straight lead in and lead out moves. Here just moves so I know how it's approaching a cut. Lead in and out are more useful in milling where you can arc into and out of a cut leaving no noticeable tool mark where the cut starts and ends.
If I understand you right, I think that's what was happening. That is, starting from OD, cutting right to left, and slowly moving towards axis of rotation. Or if you look at the plot from my program...start at the lower right. It moves left then starts over a litte closer to X. What I was thinking of was a facing cut to size on the end of the part. Before taking the diameter down make a cut from outside to the center on the end of the part. But as you say, it probably wouldn't help considering the roughing cuts to reduce diameter.
It only goes past center of rotation during the last roughing cut and the finishing cut. By which time there is little part left. I think it was possible the part got pushed into the chuck on early attempts because the depth of cut was too large. But any motion past the center line will just have the tool rubbing. But you are right, it probably doesn't matter. How did you force the cutting beyond the center line anyway?
Thanks.
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John:
Yes, I agree. Thanks.
Hugh
the calculations are done as from the centre of the tool radius but the tool is set to the edge either the side z0 or the front of the tool x when milling the x0 y0 are set in the centre of the tool.
hope that helps.
John
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Zee:
I was mostly going off your previous CamBam plot:
(http://www.modelenginemaker.com/index.php?action=dlattach;topic=9555.0;attach=114877;image)
Sorry about that. I meant Lathe Tool Radius Offset. It's in the System tab. Select the post processor (Mach3-Turn in this case) then scroll down in the lower pane. Same place where you set whether X mode is radius or not. No problem. I found it via your direction. I made up a small test part and had CamBam generate lathe code for it. I ran two versions, one with Lathe Tool Radius Offset true and one false. I couldn't see a difference in the tool paths. So, I compared the two *.nc files and found the only difference was the time stamp. Thus, this parameter doesn't seem to do anything, but I don't know what it is supposed to do? The description in CamBam documentation isn't clear to me. Can you explain what it's supposed to do?
Odd. When I did it the files were quite different. Attached is a screenshot showing a portion of the difference between the two files. (My editor has a 'file difference' feature.) Here's an explanation from CamBam about the Lathe Tool Radius Offset... http://www.cambam.info/doc/plus/cam/Lathe.htm (Scroll to near bottom). You won't see a change in the tool paths drawn in CamBam.
I'm not sure I follow. It did not start cutting at the center of rotation. It started from just outside the surface of the stock, bringing the part to diameter. Then worked along the tip, then made the final roughing and finishing cut starting at axis of rotation. I think the reason you mentioned 'not reaching the bottom of the cut on the left side'...CamBam just shows the tool path and not the shape of the tool. In my program, the crosshair represents the shape of the tool. Just pretend it's a circle. (I had enlarged the part radius a bit so the cutter wasn't cutting along too much of its circumference. My bad, I'm not explaining things well. I was thinking of the final roughing and finishing cuts. They do cut at the center of rotation, but after the previous cuts it's taking little material. Although that depends on how much stock is left to cut on the right end. Looking at the CamBam plot above, the center of the tool radius, plotted points, do start at the center of rotation for the last rough and the finishing cuts. It should be cutting the whole profile.
In this plot again, it looks to me like the tool path doesn't reach the center of the circular profile on the left end. This is what I meant in my previous email. It's hard to see this in your plot as the profile itself isn't shown. If you increased this profile arc you've likely fixed this. The profile is the red line. I don't understand why you say the profile itself isn't shown. I did enlarge that arc a bit (not shown) but didn't see any real difference.
I've seen references to 'lead in'. I don't know anything about yet or what it means. This screen shot (attached) of CamBam for my trial part shows straight lead in and lead out moves. Here just moves so I know how it's approaching a cut. Lead in and out are more useful in milling where you can arc into and out of a cut leaving no noticeable tool mark where the cut starts and ends.
Ah. Thanks.
If I understand you right, I think that's what was happening. That is, starting from OD, cutting right to left, and slowly moving towards axis of rotation. Or if you look at the plot from my program...start at the lower right. It moves left then starts over a litte closer to X. What I was thinking of was a facing cut to size on the end of the part. Before taking the diameter down make a cut from outside to the center on the end of the part. But as you say, it probably wouldn't help considering the roughing cuts to reduce diameter. CamBam doesn't support facing. I would need to insert the needed g-codes into the file. In this case, I had faced the part on my other lathe. Not the best idea as accuracy can suffer but was good enough for this experiment.
It only goes past center of rotation during the last roughing cut and the finishing cut. By which time there is little part left. I think it was possible the part got pushed into the chuck on early attempts because the depth of cut was too large. But any motion past the center line will just have the tool rubbing. But you are right, it probably doesn't matter. How did you force the cutting beyond the center line anyway? I'm not sure about that. By the time the final roughing cut and the finishing cut start, the profile will have a series of steps in it from all the prior roughing passes. Then, as the tool tip moves along the profile, the steps are smoothed out. Think of the tool tip as a circle. It has to get past the center line in order for the left edge of the tool tip to cut. Note that the actual part of the tool tip that cuts moves as the tool tip 'rounds the corner' of the profile. The Lathe Tool Radius Offset made the difference. Setting it true caused the tool tip to go past the center line. What's curious to me...with the offset false there was still code showing the tool tip going past the center line but only by 1 or 3 thou. With the offset true, the tool tip went past the center line by the radius of the tool tip, which was what I wanted.
From what I can tell, CamBam plots the center of the tool. The post processor can make additional changes to the paths the tool takes depending on parameters (such as the lathe tool radius offset). This is why I wrote my little program to display the 'new' tool paths and give some sense of where the edge of the cutter is. In hindsight, I didn't really need my little program. Viewing the output file showed what was happening to the tool tip.
Thanks again, Hugh, John, and all the rest. All of this was very helpful (as well as fun and satisfying). :ThumbsUp:
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Zee:
Comments below:
Odd. When I did it the files were quite different. Attached is a screenshot showing a portion of the difference between the two files. (My editor has a 'file difference' feature.) Here's an explanation from CamBam about the Lathe Tool Radius Offset... http://www.cambam.info/doc/plus/cam/Lathe.htm (Scroll to near bottom). You won't see a change in the tool paths drawn in CamBam.
Yep. I wasn't saving the post processor correctly. Now it looks like a radius difference in X and Z which would match the desctiption CamBam gives. The description makes more sense now.
It's hard to see this in your plot as the profile itself isn't shown. The profile is the red line. I don't understand why you say the profile itself isn't shown.
Here I was referring to the plot from the program you wrote. I see the profile on the CamBam plots but not in the graph from your program.
CamBam doesn't support facing. I would need to insert the needed g-codes into the file.
I agree, I couldn't find an easy was to do a facing cut. Seems like there should be a way but I couldn't find it. Tried a milling profile cut which looked OK but the G-code didn't come out right. Could hand code it but that is a pain, particularly if you modify anything.
From what I can tell, CamBam plots the center of the tool. The post processor can make additional changes to the paths the tool takes depending on parameters (such as the lathe tool radius offset). This is why I wrote my little program to display the 'new' tool paths and give some sense of where the edge of the cutter is. In hindsight, I didn't really need my little program. Viewing the output file showed what was happening to the tool tip.
It seems like this is true. The machine controller makes additional adjustments. I'll likely use the nose radius, leave the "Lathe Tool Radius Offset" true, and enter the nose radius in LinuxCNC. That seems to work for my setup.
A good learning experience all the way around. Thanks.
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It's hard to see this in your plot as the profile itself isn't shown. The profile is the red line. I don't understand why you say the profile itself isn't shown.
Here I was referring to the plot from the program you wrote. I see the profile on the CamBam plots but not in the graph from your program.
Ah yes. I didn't bother to plot the profile. My little program was built from other programs I'd written in the past. All I had was the ability to plot straight lines, not circles or ellipses. Plus, I would have had to figure out how to input the profile (and scale it correctly) or figure out how to read and plot the DXF file.
In fact, I only plotted G1 movements. G0 seems to be used for rapids to clear the part. G2 requires a different Bresenham algorithm which I didn't want to bother with. G2 only came into play during the last roughing cut and during the finishing cut. (I suppose I could find some Visual Studio routines but I used what I'd written years ago.)
Lastly, I was more interested in seeing what was going on to the right of the part. The crosshair represented the tool tip so you can actually 'see' the profile by 'connecting' the appropriate hair ends (and squinting). If you draw a circle around and encompassing that tip in the neck...that would be the radius of the neck. The radius of the neck is slightly larger than the radius of the tool tip (crosshair) but the resolution of the system prevents seeing very small movements.
Thanks again. I'm very glad if you found all this useful.
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Well I'm having trouble finding/selecting a cutting system for that finial. Too many choices and not enough knowledge.
The nikcole system looks interesting but trying to find the right insert, as well as holder, is difficult. I just don't know what I'm doing.
I think the HSS cutter I modified will work well enough. I just need to get better at grinding the cutter shape.
In the meantime I'm wondering how to cut the part in the attachment.
The attached part is a simplified version of what I want but it will do.
Imagine a hole in the left end for a live center and imagine some parent stock on the right end.
I'm wondering if a thick parting tool would do the job. See 1st attachment.
That actually raises another question. I have a 1/8" wide parting tool which I've never used. I generally have used a .04 or 1/16 (P1) parting tool.
Under what circumstances would someone use such a thick (1/8") parting tool?
I'm hoping that the thickness plus low feed and light cuts will help the tool from bending.
Thanks.
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Don't bother with my last post. It doesn't work. I need to noodle on that some more.
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Temporarily closing shop.
We're back on daycare for my grandson and T has a decent freelance job that takes her time.
The booger really enjoys coming into my shop and playing so I've had to baby-proof it.
Family first.
Not that I haven't been struggling anyway. Ever since I retired (two years ago), my motivation and interests have taken a nose dive.
I hope to keep checking in and giving a few of you some pokes.
This is a great forum...with great people...not just people good at machining but just good overall. I love the learnings.
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Now I have grand-daughter spending time in the shop.
She's playing with a 3D printer pen.
Oh well. It's more important to 'influence' my grand-children right now.
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I've been pinged by a couple of friends here so I thought I'd explain myself...
Shortly after my last post, my wife was diagnosed with cancer in her esophagus. It may also be in a couple of lymph nodes near her clavicles.
No one knows why. She's not a smoker. Apparently this problem is common to smokers.
Surgery was deemed too risky. Tumor is in the middle of esophagus and very near to aorta, air passages, and heart.
Surgery would have meant removing the entire esophagus, making the stomach into a tube, and connecting the stomach near her neck. Fun, eh?
Fortunately, we live in an area that has proton radiation available. The radiologist seems optimistic. And the type of cancer she has is very susceptible to radiation.
This will be weeks of everyday treatment and likely followed by chemo.
We're doing okay but it's going to be a long haul.
Shop is going to be closed for a while.
I don't mean to bring anyone down but thought my friends would want to know.
Stay safe and healthy everyone.
If I don't get back for a while...thanks for your thoughts.
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Zee,
Very sorry to hear this. I hope all goes well. We will be thinking of you both.
Colin
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Our best wishes and thoughts!!
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Sorry to hear this Zee, my thoughts are with you and hoping for the best possible outcome.
Dave
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Zee,
May I wish you both the strength and courage needed to get through these next few months.
Hang in there
Mike
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Zee:
Not the best of news. We'll be sending you our best thoughts. I trust there will be a good outcome.
Thanks for keeping all of us in the loop.
Best Wishes.
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Very hard news to hear, and I'm sure much more so for you, your wife, and family.
We will be thinking of you all and wishing you the best, hoping for the best possible outcome.
Kim
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Sorry to hear the bad news. Best wishes for it to work out well.
--ShopShoe
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Zee, my prayers are with your wife and with you.
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Sorry to hear this, Zee. Our thoughts are with you and your family.
Scott
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Thank you all so much.
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Well it's March. Last post was July.
First, an update on my wife.
Surgery was a no go. Cancer had spread to a couple of lymph glands and lungs.
Proton radiation and chemotherapy didn't work.
She's now undergoing immunotherapy. She's had 3 treatments.
A 4th treatment a week from tomorrow and then a scan a few weeks after that to see how it's going.
She's been on a feeding tube since last summer and takes everything through the tube.
She can only swallow about a 1/2 cup of liquid a day.
Every 4 hours I give her meds and water through the tube. About 9 large syringes worth.
She's generally always in pain even with methadone and oxycodone.
She's better than she was a few months ago and comes out of the bedroom once in a while.
It's been grueling and I've had no shop time.
Lately though I've been giving a lot of thought to the shop, machining, and hobbies in general.
I've realized that I'm not a hobbyist. I'm a dabbler. Always have been.
I've come to accept that my joy comes from putzing around, always starting things and never finishing them.
Be it machining engines, playing with electronics, programming, model making, the list goes on and on.
It's been a release to accept myself.
I'm thinking of naming my shop "Das FurzHaus". There are 3 meanings behind that (no pun intended) and I'll leave it to you all to figure them out.
I've also realized that getting the bigger machines was a mistake.
So I plan on selling them off and going back to the minis. I hadn't realized how much I enjoyed them.
I'm thinking of the LMS HiTorque machines. I'll probably have many questions for you all as I go along.
It'll be slow going as I'm facing an interesting summer.
Besides the pandemic and caring for my wife, I've got two daughters...
Youngest is due March 18. Eldest is due May 1.
They both live nearby so I'm sure I'll be busy helping them.
I apologize if this is all a bit personal but I consider many of you friends and thought you'd like to know what's going on.
I can make no promises as to how often I can make it on the forum.
You all take care and keep making and posting.
And don't forget pictures!
Keep those 'happy dances' going.
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Thinking of you Zee, as you know the steamer household has had a visit from the C monster as well...were doing well and it looks.like my daughter beat it...again...thoughts and prayers my friend...
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Zee, I did wonder why we hadn't heard from you. Sad to hear about your wife and the consequent stress and heavy workload for you. I can only hope and pray for a good outcome. Do not apologise for your post.....you ARE among friends. Stay positive if you can.
Steamer, Good to hear y'all beating this horrible virus. Best Wishes Terry
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Zee, I did wonder why we hadn't heard from you. Sad to hear about your wife and the consequent stress and heavy workload for you. I can only hope and pray for a good outcome. Do not apologise for your post.....you ARE among friends. Stay positive if you can.
Steamer, Good to hear y'all beating this horrible virus. Best Wishes Terry
Well...no quite my daughter beat Cancer for a second time. 6 rounds of chemo and a bone marrow transplant....been a hell of a year. Agin thoughts and prayers to you zee...
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My apologies steamer. I miss understood the "C Monster".. Best Wishes Terry
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Nice to hear from you again Zee, sorry it has been such a lousy year or so for you. You are missed around here, whether it be as a big project'er or a dabbler, defintely stop in when you can. Best wishes on the future developments, we are all behind you!
:cheers: Chris
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Thanks for the post, Zee. Thanks for sharing with us. I have been thinking about you and wondering how it was going, so nice to get an update. Though the news doesn't sound so good. I'm very sorry to hear that the disease has been so hard on your wife, you, and the whole family. Our thoughts and prayers are with you.
As for the machines? Get what you want and do what you want with them. It's all about enjoying your time and if dabbling is your thing, then dabble away! But share your dabblings with us when you're able to.
Take care of your wife and kids. We'll be here when you have time.
Kim
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Hi Zee, I am so sorry to hear about T and the year you have been through. Your devotion to her through all this definitely makes you a hero in my view.
My thoughts and prayers go out to you and your family. You have many friends on the forum and are definitely missed when other priorities call you away.
As for your joy in dabbling, there is so much that strikes a chord there. Many of us feel the excitement of starting a new project, but also have unfinished projects on the shelf for one day that we imagine will come. Enjoy what you enjoy, and keep the best unfinished ones for some future day.
And do look forward with joy to those two new grandchildren whose arrival is fast approaching.
MJM460
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No apology needed Zee.
Sorry to hear about T's pain and tribulations - I really hope she gets well again, from that 'Damned disease' as we call it in my family.
So you are going to be a GrandPa twice over soon, eh -> some joy coming to you and your family soon then :)
While I do finish some projects - you have now told me (indirectly) that I'm a dabler too ;D
Best wishes to you and your family
Per
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".....As for the machines? Get what you want and do what you want with them. It's all about enjoying your time and dabbling is your thing, then dabble away! But share your dabblings with us when you're able to........"
Best advice I've heard this year!......
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Very sorry to read about your wife being ill, Zee.
I wish you all strength and courage in your support of her.
gary
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Thank you all. It really means a lot.
Although I haven't done anything in the shop, I'm getting enjoyment out of drawing up a new shop layout, making lists of goodies I want to get, and working on converting the Sherline mill to CNC.
I'm thinking of using the mill for engraving.
Probably won't be until late spring or early summer before I can do anything more meaningful.
Thanks again!
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You just keep being Zee...youll be by eventually...we'll be here then and in between....
Thinking of ya man
Dave
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Thanks Dave.
Well finally had a bit of time in the shop. (Not for a good reason, wife was in hospital. Home now and doing better.)
Wired up three steppers to D-subs.
Tested with Mach3.
Mounted X and Y.
Couldn't get one bolt removed from the carriage when taking off the manual stuff. So drilled it off. Unless I can get the stub out, it won't be a manual system again.
Now for the Z axis.
Crud. They had sent the wrong leadscrew.
Asked Sherline what I should do and they said they're sending the correct one.
Yay!
I won't name names but someone pointed out my 3rd signature line "Zee - Another Thread Trasher".
Time for a change.
I'm thinking of "I'd like to see the great Leslie try that!".
It's also a quote from "The Great Race" as is "To work. To work.".
I just saw the movie again the other night for the umpteenth time. Pretty silly.
I was 12 when I first saw it. It's been a huge influence in my life.
The cars, the airplane, the submarine.
"The Absent Minded Professor" and his basement lab was another.
Or "Those Magnificent Men and Their Flying Machines".
There were more.
I'd be interested in hearing what movies influenced you all when you were a kid. I mean a real kid in age. Not now. ;D
I'll let you be today's thread trasher. :Lol:
I digress.
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Bummer about the wrong part, but in my experience Sherline is very good about fixing things.
As for movies from kid-dom, also loved Magnificent Men And Their Flying Machines. Animated movies like Robin Hood (the one with animal characters), but my real favorites were Bugs Bunny, Roadrunner, Daffy Duck cartoons. My front hall has a Roadrunner/Coyote animation cel on the wall, guess I am still a fan! Somehow I bet you liked Foghorn Leghorn too...
:cheers:
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Prayers and thought go with you my friend keep your spirits high it’s in gods hands. We enjoy hearing from you Zee, but not bad news and we will be hear when your ready....
Best regards
Don
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Do what is important at the time, the rest can always wait.
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Hi all.
It's been a while but I thought some of my friends would want to know.
My wife of 45 years passed away May 25th from esophageal cancer. She was only 65.
It's been a hard road for myself and my kids but we're getting through.
I sold my big lathe and mill and went back to a mini-lathe and mini-mill. More my size.
I also finished converting my Sherline lathe and mill to CNC.
Keeping busy helps.
Unfortunately, I have no motivation to do anything else in the shop. That will take a while.
Will I get back in the shop? Will I be back to the forum? I can't say right now.
I know time heals but it can take a while.
You all take care and know that I'm lurking...infrequently perhaps...but lurking.
Stay healthy my friends.
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Hi Zee,
So sorry for your loss. Stay strong and keep busy at whatever interests you. Our thoughts are with you.
Chris
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Carl,
My deepest sympathies for your loss. We are all here for you.
Sincerely,
Bob
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Condolences to you and your family my friend. Good to hear from you and that your still with us. Take all the time you need Zee and I know it’s hard to get back to the things you love to do and it will come in time. Stay well my friend we will pray for you….
Regards Don
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Hi all.
It's been a while but I thought some of my friends would want to know.
My wife of 45 years passed away May 25th from esophageal cancer. She was only 65.
It's been a hard road for myself and my kids but we're getting through.
I sold my big lathe and mill and went back to a mini-lathe and mini-mill. More my size.
I also finished converting my Sherline lathe and mill to CNC.
Keeping busy helps.
Unfortunately, I have no motivation to do anything else in the shop. That will take a while.
Will I get back in the shop? Will I be back to the forum? I can't say right now.
I know time heals but it can take a while.
You all take care and know that I'm lurking...infrequently perhaps...but lurking.
Stay healthy my friends.
Oh man Zee. I'm so sorry to hear this, my thoughts and prayers are with you. That horrible disease has touched many, and I hate it....Like nothing else
I want you to know we're thinking of you and love you. You are my friend, and always will be...this forum or otherwise Lurk if you must...but poke your head in every once in a while...just to say hi.
My condolences to your family, and to you my friend.
Dave
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Zee, this is one of those times that I just don't know what to say. I'm so sorry for the loss of your wife; my condolences to you and your family.
I have been working in the shop this afternoon and can't stop thinking about you.
Take care my friend.
Dave
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I am so very sorry Zee. Please accept my sincerest condolences. Be well.
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Hey Zee,
So sorry to hear this incredibly sad/hard news. Thank you for sharing with us. Know that we're thinking about you.
KIm
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Hi Zee, So sorry to hear the sad news. Words are not adequate in the circumstances, but know that your friends around the world are thinking of you and praying for you at this time.
You will always have friends here when you feel up to looking in.
MJM460
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Zee, this is sad news indeed. My condolences to you and the rest of your family. From your past posts, I know you have a closely knit family. That will certainly help during these difficult times. Stay strong and please check with us once in a while.
Jim
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Zee:
Very bad news. I wish you the best as you work through these times. I do hope you'll stay involved with the forum, it isn't the same without you.
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I'm so sorry for the loss and pain for you and your family.
That dam disease has taken many loved ones away from me ....
Best wishes
Per
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So sorry to hear the sad news about Tee, Zee :'( Life is challenging enough and then just when you think it might pick up - it craps on you :toilet_claw:
Take your time, I am sure we would all love to have your "special input" on our threads :embarassed:
Look after yourself and your family - they need you. We will be here for you when you are ready.
Jo
P.S. Sounds like you need a curry :Love:
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I am so sorry to hear this Zee.
I can only imagine how you feel.
l almost lost my wife in Dec. Praise God didn't. That was bad enough.
Keeping you and yours in prayer.
Ron
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Sad times :( Remember all the good times, they are important :) :) :)
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Thank you all very much. It means a lot to me.
She was a very talented, intelligent, and beautiful woman. I miss her terribly.
Hopefully it won't be long before I get motivated to cut metal.
But the holidays are approaching fast and it's going to be a very rough time without Teresa.
I can't imagine putting up the Christmas tree with all of her homemade ornaments.
Happily, my two daughters live very close to me and I see each at least twice a week.
They've taken well after Teresa with cooking, gardening, writing, hobbies, etc.
They're fine daughters and I'm very proud of them.
They've been extremely helpful to me and I hope I am as well to them.
Both daughters were pregnant during this time. Can you imagine what they went through?
Happily both gave birth just weeks before Teresa's passing and she was able to see them.
I now have two granddaughters from one and two grandsons from the other.
It's good to have friends and a forum that lets one release once in a while.
Thank you.