Model Engine Maker

Supporting => Tooling & Machines => Topic started by: Jasonb on February 20, 2019, 02:20:51 PM

Title: Going over to the dark (CNC) side!
Post by: Jasonb on February 20, 2019, 02:20:51 PM
This turned up earlier today

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825074.jpg)

And one of these KX-3 machines was inside

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825076.jpg)

So it looks like I'm going to have to work out what it does. Where are the handwheels :headscratch:

Not been a bad week for packages as these turned up earlier, now that's what I call a generous chucking spigot :)

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/20190220_141123_zpsiqq8z3vv.jpg)

Title: Re: Going over to the dark side!
Post by: steamer on February 20, 2019, 02:45:57 PM
Do let us know about the KS3
Title: Re: Going over to the dark side!
Post by: b.lindsey on February 20, 2019, 03:00:37 PM
Where's that Darth Vader emoji when you need it  :lolb:

Bill
Title: Re: Going over to the dark side!
Post by: kuhncw on February 20, 2019, 06:04:56 PM
Nothing dark about it.

Enjoy the CNC!

Chuck
Title: Re: Going over to the dark side!
Post by: Jo on February 20, 2019, 06:34:19 PM
Just need a bigger workshop so you can fit it in  ::)

Jo
Title: Re: Going over to the dark side!
Post by: Admiral_dk on February 20, 2019, 09:12:28 PM
Google  "KS-3 machine" did not give any clues and adding CNC to the search was no help either  :headscratch:

Will you elaborate with more info later Jason ?
Title: Re: Going over to the dark side!
Post by: crueby on February 20, 2019, 09:25:02 PM
Google  "KS-3 machine" did not give any clues and adding CNC to the search was no help either  :headscratch:

Will you elaborate with more info later Jason ?
Typo - its a Sieg KX-3
Title: Re: Going over to the dark side!
Post by: kvom on February 20, 2019, 10:09:25 PM
Rather than going to the dark side you have seen the light.   :cheers:
Title: Re: Going over to the dark side!
Post by: Jasonb on February 28, 2019, 09:05:06 AM
I got my Mack3 licence yesterday which meant I could run more than 500 lines of code so had a bit more of a play. The Sieg logo comes as a demo code so I ran that first.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825586.jpg)

This machine was a customer return and was known to have issues with the Z axis having been crashed into the top of the column and I was having problems getting the heights right so pulled all the electronics off the back (8 screws) so I could have a better look at the mechanicals, found something loose and tightened that up.  I ran this code about 8 times last night and could not get depths right - (tool finished up higher than when it started) before tightening the loose part. Have run it 3 times this morning and so far all seems OK, will run it a few more times later..

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825631.jpg)
Title: Re: Going over to the dark side!
Post by: Jasonb on February 28, 2019, 11:21:52 AM
KdVKuZ7b9XI
Title: Re: Going over to the dark side!
Post by: jadge on February 28, 2019, 12:37:42 PM
Never thought I'd see the day..................  :o

Andrew
Title: Re: Going over to the dark side!
Post by: Jasonb on March 01, 2019, 05:55:38 PM
Looks like my days of buying cast iron flywheels could be coming to an end if I can produce ones like this in metal, notice that it even has the spoke halves out of line just like the real thing :shrug:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825715.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825716.jpg)
Title: Re: Going over to the dark side!
Post by: b.lindsey on March 01, 2019, 06:30:33 PM
What is the material Jason? Some type of plastic I assume, but looks fuzzy in places so wasn't sure.

Bill
Title: Re: Going over to the dark side!
Post by: ddmckee54 on March 01, 2019, 07:37:19 PM
With fuzzies like that, it's most likely some flavor of that brown stuff that Jo hates.

Don
Title: Re: Going over to the dark side!
Post by: Jasonb on March 01, 2019, 07:50:55 PM
It's just some offcuts of UPVC facia board which has a dense foam type core, not the best for getting a good surface on but ideal for getting the hang of using the machine as it's a bit more forgiving if I get feed rates wrong. Having said that it's happy with me cutting it at 5000rpm and 1500mm/min (60"/min) feed with a 3mm 3-flute cutter.

It does have a black woodgrain finish on one side ;)
Title: Re: Going over to the dark side!
Post by: Admiral_dk on March 01, 2019, 07:58:36 PM
I can relate to your trials as I either cut air first time I try a new G-code file or a piece of soft scrap if possible - my very first was soft wood. Now I just need a mill / router that will do aluminium and steel without problems ... the one at work is for PCB (Printed Circuit Board).

Congratulations with yours and enjoy  :cheers:
Title: Re: Going over to the dark side!
Post by: kvom on March 01, 2019, 10:02:33 PM
I use GWizard for feeds and speeds.  I break very few mills as a result.
Title: Re: Going over to the dark side!
Post by: TobyTetzy on March 02, 2019, 08:21:32 AM
Hello Jason,

you have a great machine, I like it.
I also use Mach3, which CAD and CAM software do you use?

Greeting Toby
Title: Re: Going over to the dark side!
Post by: mikemill on March 02, 2019, 10:23:26 AM
Jason

Welcome to the wonderful world of CNC, you are about to discover a whole new world of model engineering.
Models you made in the past such as enlarged Antony Mount's engines without castings become a lot easier.

I took the plunge eight years ago and have made many models on the mill since. also had bags of fun

A few tips, watch out for is rapid movements crashing into work hold clamps, easy tool change method is to use 6mm throw away cutters in one collet you get a range from 1mm through to 6mm

The only restriction is your imagination

Enjoy

Mike
Title: Re: Going over to the dark side!
Post by: jadge on March 02, 2019, 11:15:48 AM
A few random notes:

Personally I don't like Mach3 - I used a customised version for the Tormach, but the screens are messy and inconsistent, and a lot of the 4th axis stuff plain didn't work. And tool tables weren't stored at the time of filling. I now use PathPilot, which I believe is based on Linux.

Early on (10 years ago) I had a number of issues using a basic PC for control - I've still got the clamp bolt with half the diameter missing after the cutter went doolally. Turned out there was an internal issue with the PC that caused the program to change to incremental mode at a tool change, but only about 1 in 20 times.

After a lot of faffing about touching off tools to fill tool tables I took the plunge and bought an electronic tool height setter - really makes life easy.

I used to air cut before cutting metal for real. Experience shows that my CAM program doesn't always generate G-code that reflects the toolpath it is displaying. I now check the actual code with a backplotter (NcPlot) which gives enough confidence that I don't need to air cut first. If nothing else I get bored air cutting a program that may take several hours to run.

I've tried feed 'n' speed programs, but they seem to produce silly answers. I prefer to use experience to set spindle speeds and the calculate feeds from the cutter manufacturer's recommended chip loads, which can vary within a program according to width of cut to account for chip thinning.

I don't recall anyone mentioning post-processors? I've written my own to include a setup line to ensure I always operate in the planes and units I want and to cancel unwanted modal commands. The post-processor also tells the machine how to interpret some commands, like G02 and G03, that have multiple possible parameters. Since I don't have an autochange tool system I also use the post-processor to move the tool somewhere sensible (home) when a tool change is needed.

One of the real challenges of CNC, which rarely gets a mention, is fixtures. It can require some imagination to design fixtures for the work so that the total area to be machined is clear, the toolholder clears clamps (note toolholder, not just the tool) and the work and/or scrap material doesn't jam things as the cut finishes.

A significant proportion of what I CNC mill are parts I've designed. It pays to think about the machining while doing the design, and there are important differences from manual milling, which requires a different mindset.

There's probably other things I've forgotten, but I now need to get my rear in gear and drive over to Oxford Airport to collect the oxygen cylinder for my glider, which has undergone it's five yearly inspection and pressure test. It runs at 2000psi and sits alongside me in the glider, so it would be messy if it failed.  :embarassed:

Andrew
Title: Re: Going over to the dark side!
Post by: RonGinger on March 02, 2019, 01:23:40 PM
CNC is by far the best way to break tools. A couple days ago I was using a 1/4" end mill to cut out a pocket in a loco frame. A combination of a dumb programming error, I missed a plunge depth setting and went to fast. That overloaded the X motor and a mounting screw slipped so the tool stalled and did a great attempt to friction weld itself to the work. I actually turned the tool cherry red for about a 1/4 inch long. The end is now a melted glob.

All CNC machines seem to have the big red Estop buttons. I believe these are quite useless, as the damage is always done well before you even have the reaction that says its time to hit the button. I saw a custom control panel once that had that button labeled "Oh Shit", I believe a much more appropriate label.

But I will never give it up, when its right it is very good.
Title: Re: Going over to the dark side!
Post by: Woodguy on March 02, 2019, 03:11:29 PM
Just a suggestion - buy or make some machinist's wax, or as an alternate, use blocks of insulating foam for testing.
Title: Re: Going over to the dark side!
Post by: Jasonb on March 02, 2019, 04:30:47 PM
Toby for CAD I have Alibre Professional but not their CAM so may have a go with Fusion360, the code for the things I have cut so far has been done with Vectric Cut2D

Mike, that is what I'm hoping for, I won't be getting rid of the manual mill and can't see me putting a casting onto this one but it should open up some possibilities for creating my own engines where manual would take a long time of just not be possible. I do tend to use FC-3 cutters for most things below 6mm so have a good stock of them.

Andrew, I'm going to try Mack3 to start with especially as it is all  ready set up for this machine and then as I get more used to it decide what way to go. As you know I'm not one for working out speeds and feeds prefering to suck it and see but you don't get the feel through a keyboard like you do on the manual machines but will base my settings on what I am use dto on teh X3 and that is one of the reasons I have recently fitted a tacho to it so I can see what speeds I was actually running at. The funny thing is that bot this and the SX2.7 have the direct belt drive brushless motors and they hardly seem to be running compared to the X3 with its brushed DC motor and gearbox which is so much louder when running.

Ron the UPVC board I have been cutting does have a ridgid foam core so it's a bit forgiving if settings are wrong and I have found the feed override buttom in Mach3 :)

Having said that there is only so much foam you can cut before the lure of metal becomes to much so I mounted up one the 80mm vice on loan from ARC rather than risk my own and put an offcut of 1/4" unknown aluminium in place. The part depth pockets were done with a 3mm FC3 cutter at 2500rpm, 150mm/min feed and 1mm DOC per pass. Different shapes are 1, 3 or 3mm deep. The Cut2D does seem to lift and ramp the cutter down more times that I think it really needs to and there is a slight over cut each time it does this which shows the most around the star. Apart from that you can't feel the pattern left by the cutter with a finger nail.

The two through holes were done with a 6mm FC3 cutter, 2500rpm, 150mm/min and I set it to work out its own depths in 5 passes. Finish seems nice and crisp with no indication of the hole being formed in 5 passes and a quick measure of the the square hole gives 19.99 x 19.98mm for the 20mm on the drawing which I'm reasonably happy with considering the mill is still just sat on the pallet and I have not looked at the gibs or tram.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825823.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825824.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/825822.jpg)
Title: Re: Going over to the dark side!
Post by: Dave Otto on March 02, 2019, 07:34:15 PM

All CNC machines seem to have the big red Estop buttons. I believe these are quite useless, as the damage is always done well before you even have the reaction that says its time to hit the button. I saw a custom control panel once that had that button labeled "Oh Shit", I believe a much more appropriate label.


Very well could have been my control panel.  :lolb:

Dave
Title: Re: Going over to the dark side!
Post by: kvom on March 02, 2019, 07:39:21 PM
The CAM system I and a number of other here use is CamBam.  You can try it out for quite a while for free.  I think it's quite intuitive.  You'd export DXFs from Alibre and load into CB; then apply a series of machine operations (MOPs) to the drawing.  You can also load STLs for 3D machining.  One benefit from CB is that the user forum is very active, so getting help or answers is quite quick.

The first advantage of CNC is that you never need to use a horizontal rotary table ever again.  Any cut involving and arc or curve is straightforward.

Nothing wrong with Mach3;  I used it for 6 years, although the parallel port interface and kernel interrupt pulsing meant my rapids were limited to 75 ipm (1900 mm/min).  I now run PathPilot;  here a card from Mesa generates the pulsing, and it's much smoother.  I've set rapids to 150, although I could have gone faster.  The screen layout is a lot better too.  The main disadvantage of PathPilot is that one can't jog the axes during a tool change, which is possible with Mach3.  So I need to stop the program, jog to where I can change the tool, and then select the line at which to restart.  The gcode is pretty much identical between the two controls.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 03, 2019, 10:43:04 AM
In this thread Jo commented that parts can take a long time to machine by CNC

http://www.modelenginemaker.com/index.php/topic,8873.0.html

I mentioned in that thread that the Forest engine I have been working on had several parts that I thought would be ideal for making with my new machine. I already have the parts modeled in Alibre so quickly exported a DXF of the leg into the vectric Cut2D software and 10mins later as there was a bit of a learning curve as it is the first time I have imported a DXF and have only been using for a couple of days it has produced the code.

The picture attached shows the simulated part after the metal had been "cut" on screen and you can see the top left that it will take 8.23 to cut, add another 1.28 for cutting teh web from the other side and th epart will take approx 10mins to cut, 20mins for the pair.

Doing it manually took me about 5 hours!

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Woody/20190121_1517041_zpszlsrpegf.jpg)

Think I may just cut one for the practice :)

As I said earlier I'm not going to throw my manual machines away but it does seem to make sense to use CNC on some parts.
Title: Re: Going over to the dark (CNC) side!
Post by: Jo on March 03, 2019, 11:38:11 AM
In this thread Jo commented that parts can take a long time to machine by CNC

I asked how long it took:

I can see lots of uses for one but its like 3D printers if it takes hours and hours to do the printing/machining  :Doh:

A CNC mill is a desirable item for the workshop. Being given one for free even more so  ;)

Jo

P.S Mike will confirm that I had been looking to buy a CNC mill  :-X
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 03, 2019, 11:49:32 AM
How are going to hold the stock for that part?

For the pocket, another option is to cut the inner through pocket first.,  then machine the flange with a profile.

Does your program support nesting?  That's the kind of part where you could do both at the same time.  If nesting isn't an option, then duplicate the polylines.

Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 03, 2019, 12:01:16 PM

The picture attached shows the simulated part after the metal had been "cut" on screen and you can see the top left that it will take 8.23 to cut, add another 1.28 for cutting teh web from the other side and th epart will take approx 10mins to cut, 20mins for the pair.

Jason,

 I will believe you when you have actually done it in that time.

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on March 03, 2019, 12:20:27 PM
Jason

Check out the standalone controllers like this one https://madmodder.net/index.php/topic,11598.0.html (https://madmodder.net/index.php/topic,11598.0.html) which doesn't require a PC, software, breakout board etc. John Stevenson and Steve Blackmore looked into this and were very pleased with what they found. I'd have thought something like that would be ideal for this machine.

If you want something a bit more serious, there are things like this https://newker-cnc.en.alibaba.com/product/60612188303-804601673/CNC_kit_NEW990MDCa_4_axis_for_cnc_machine_all_replace_for_gsk_cnc_controller.html?spm=a2700.icbuShop.41413.10.441e5e63dmyi40 (https://newker-cnc.en.alibaba.com/product/60612188303-804601673/CNC_kit_NEW990MDCa_4_axis_for_cnc_machine_all_replace_for_gsk_cnc_controller.html?spm=a2700.icbuShop.41413.10.441e5e63dmyi40) I got one for around £400 but that may be a bit OTT for what you need.

Murray
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 03, 2019, 01:40:46 PM
Jo,

 I based my comment on this one of yours, my bold

Quote
I can see lots of uses for one but its like 3D printers if it takes hours and hours to do the printing/machining  :Doh:

Kvom,

 I actually cut from a larger piece of material and if you look at the simulation there are some tabs around the outside. I'm happy to leave tabs as the parts had all the corners knocked off after machining to make them look more like castings and less like cut from barstock.


I've not looked for nesting but will do so and can see it would be good if you had several parts, for now just moving the flat bar along in the vice is OK.

Mike (Vixen)

I ran a test in the UPVC and it cut in that time though could have been a lot faster. After doing that I thought I would play safe as it's early days and reduced DOC to 1mm but did up the speed to 3000rpm and added an extra tab. This added about 3mins to the job according to Cut2D.

I'd be interested to know what sort of time you would expect it to take from your machine or anybody else for that matter, let me know if you want the part file. I'm just using a 6mm FC-3 cutter for now and could go faster if I changed to an aluminium specific cutter, also don't have any chip clearance or lubrication sorted yet so need time to keep up with that manually.

Murray,

Good to see you chipping in here, would definately be interested in how long this would take you as having seen your machine in action it can shift metal at a fair old lick :o

Yes I remember the posts about the alternative driver over on ME but will stick with this setup for a while until I find out what I want out of the machine.



So this is the test piece done in the 8mins for the main side, you can see the tabs around the edge but it has not cut through as its thicker than the metal part.

(http://img.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03554_zpsooinstol.jpg)

Now when I loaded up the revised code for the metal version I noticed that there was an extra path showing on the screen. Should really have stopped there and sorted it out but decided to just keep the mouse over the stop button.

(http://img.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03553_zpsgoru6qf6.jpg)

At least I have learn one thing today as with about 30secs left to run I got one of the unique features that Jo mentioned but stopped it soon enough so I need to trust whats on the screen

(http://img.photobucket.com/albums/v156/jasonballamy/Engineering/20190303_122727_zpszatyultn.jpg)

I did not video all the cutting but have stitched 3 clips together which show approx the first cut of each of the three paths, think I could also speed up the ramping which would reduce overall time a bit.

zyzXaDW7chs



Title: Re: Going over to the dark (CNC) side!
Post by: steamer on March 03, 2019, 02:05:32 PM
Yup    cnc tends to be pricey..    Yup it takes a while to climb the learning curve hill.   What isnt being mentioned is the set up time saved.   The tooling saved.

Think about those curves.   On the manual, theyre a RT job and a break down and set up cycle.   Everytime you break it down and set back up is time and loss  of accuracy.   You need to spend money ona rotary table and the furniture it takes to use it.    You need to schelp it on and off the mill, and you need to store it.  With CNC...you need an endmill Nd one set up.    Used right, cnc rocks!
Dave
Title: Re: Going over to the dark (CNC) side!
Post by: b.lindsey on March 03, 2019, 03:49:53 PM
Dave, remind me which tormach you have at work?

Bill
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 03, 2019, 04:26:49 PM
Apart from the fact that I used a scrap bit of 6mm aluminium that had a hole just in the wrong place this is it with all the machining done from the front. Just under 12mins from pressing run to completion.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/DSC03555_zpsdp0kqawh.jpg)

I'm sure it could be run faster, at least that is what Ketan is telling me but then again I don't think he knows machines can be run slower than 5000rpm  :ThumbsUp: Also he and the late JS used these these machines to make parts to sell so they don't want to be wasting time.

I'm sure JS has a chuckle in his grave when people say they prefer British Made tools, what would they say if they knew he was banging them out on a similar machine to mine along with all those extras for Myfords :LittleDevil:

(http://www.stevenson-engineers.co.uk/files/lathetools1.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: crueby on March 03, 2019, 04:28:45 PM
Much satisfaction to be had from cranking the mill with your own paws,  but there is!      Hmmmm!!
(https://i.postimg.cc/9F1NqK7D/IMG-2336a.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: steamer on March 03, 2019, 04:29:42 PM
Dave, remind me which tormach you have at work?

Bill
Tormach  PCNC 440
Title: Re: Going over to the dark (CNC) side!
Post by: b.lindsey on March 03, 2019, 05:02:20 PM
Ok thanks.

Bill
Title: Re: Going over to the dark (CNC) side!
Post by: Woodguy on March 03, 2019, 05:10:58 PM
I converted my SX-3 to CNC and have used it quite a lot. The problem with it though is that is has a maximum spindle speed of 1800 rpm. Since many of the parts I wanted to make were small, and needed small cutters, the machine required extremely slow feed rates. A good feeds and speeds calculator like GWizard is very helpful in keeping cutters in one piece.  Using the biggest cutter that would do the job was essential.


Fusion 360's cam really works well and the adaptive clearance toolpath is particularly useful.


I solved my spindle speed problem by shifting those parts to my CNC router with a 24K rpm spindle.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 03, 2019, 05:19:37 PM
Yup    cnc tends to be pricey..    Yup it takes a while to climb the learning curve hill.   What isnt being mentioned is the set up time saved.   The tooling saved.

............................................

Quite so Dave, I needed two plates machining to mount the parts onto with a different ctr point on each and each part needed to be mounted and removed six times. Not to mention the constant worry of winding a handle too far!
Title: Re: Going over to the dark side!
Post by: jadge on March 03, 2019, 08:17:16 PM
I now run PathPilot;  here a card from Mesa generates the pulsing, and it's much smoother.  I've set rapids to 150, although I could have gone faster.  The screen layout is a lot better too.  The main disadvantage of PathPilot is that one can't jog the axes during a tool change, which is possible with Mach3.

Yes, that's a bit of a pain. I used to manually add a G00 Z move to the program just before each toolchange. But I kept forgetting, so I've now set a reference point on the machine and I've tweaked the post-processor to include a G30 command as part of the toolchange sequence.

Another issue with PathPilot is that being a US program the metric side is a bit cavalier. A maximum jog increment of 10mm is likely to require an underwear change if you're not expecting it! Although I design in both metric and imperial I run the CNC mill solely in metric, mostly with metric cutters.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 03, 2019, 08:51:35 PM
A few more random thoughts:

A CNC mill and 3D printer are not the same. One is a subtractive process and other is an additive process. The way parts are designed for each machine is different. Something that is easy on a CNC mill may be difficult on a 3D printer and vice versa. The 3D printer is certainly the slowest, as one is limited by the fixed nozzle diameter and limit range of height steps. Whereas for a CNC mill you can just use a bigger cutter, within the power limits of the machine. A useful feature of the more complex CAM programs is re-machining. As an example take the nameplate made by JasonB. To decrease cutting time you could rough out the shape using a large cutter. And then remachine with a smaller cutter to finish off the small internal radii. The CAM program knows where the larger cutter has been, so the smaller cutter only mills out the features it needs to.

My CNC machining times have ranged from less than a minute to over 6 hours. But of course you can go and do something else, like make tea or cut the lawn while it's running. Same for a 3D printer, I sometimes leave mine running overnight.

I'd have tackled the engine pillars in a slightly different way. I'd have done a helix all the way through in the centre and then incremented out, leaving about 0.5mm of stock. Then I'd have done a profile pass full depth to finish using a circular approach and retract. That way you avoid possible tool marks from multiple passes, and minimise tool deflection. I'd then take out the recess in one pass. For the outer profile I'd probably do it in two depth passes, again leaving about 0.5mm stock. Followed by a full depth profiling pass. I'd probably leave the tabs, but experience shows they're a PITA to remove without impairing the visual appearance of the part. At least I'd try and put them in places that mate with other parts so they're not seen.

Using a CNC mill has changed the way I design parts and assemblies, and has also changed the way I machine, some of which has fed it's way back to the way I use the Bridgeport mill.

There are several uses for the CNC mill in my workshop:

To make repetitive parts, like traction engine wheel spokes that would be a pain to do manually

To make parts that could be done manually but would be time consuming to set up - like radii and fancy profiles

To make parts that are impossible on my manual machines like special cutters and true bevel gears

To save time and avoid foul ups when making parts commercially

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 03, 2019, 11:55:16 PM
My PathPilot screen has 1mm as the maximum jog.  I also set jog feed rate to 40% of rapid.
Title: Re: Going over to the dark (CNC) side!
Post by: steamer on March 04, 2019, 12:54:29 AM
My PathPilot screen has 1mm as the maximum jog.  I also set jog feed rate to 40% of rapid.

Ditto
Title: Re: Going over to the dark (CNC) side!
Post by: Jo on March 04, 2019, 07:31:36 AM
Using a CNC mill has changed the way I design parts and assemblies, and has also changed the way I machine, some of which has fed it's way back to the way I use the Bridgeport mill. There are several uses for the CNC mill in my workshop:

To make repetitive parts, like traction engine wheel spokes that would be a pain to do manually

To make parts that could be done manually but would be time consuming to set up - like radii and fancy profiles

To make parts that are impossible on my manual machines like special cutters and true bevel gears

To save time and avoid foul ups when making parts commercially

Thanks Andrew, all of those confirm my thoughts of having CNC at home.

Short term I am delaying acquiring CNC as it is too much like what I used to do at work and I am trying to forget that horrible time of my life  :ShakeHead: Longer term with the likes of Honda pulling out of the UK I suspect there are going to be a number of machine tool acquisition opportunities to be had over the next two years and I can see CNC being in the mix of tools that become available so it could be something to spend some spare cash on invest in  :-X The far easterner tool manufacturers, once you get above their built down to a price DIY machines, do a reasonable compact CNC - the one Jason was given was one I was looking at but I couldn't justify the cost  :hellno: .

As for uses of a CNC ... I do have a number of engines with multiple items - there are a few traction engine spokes to make :) but the items that are really going to be multiples are my big rotary/radial builds - the Anzanis, the Bentley and the Gnomes. I am not sure if the straight 4 engines would benefit from CNC as much  :noidea:


One of the advantages of being retired is you have plenty of time  :headscratch:

Jo

 
 
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 04, 2019, 09:22:31 AM
My PathPilot screen has 1mm as the maximum jog.  I also set jog feed rate to 40% of rapid.

That's useful to know. I contacted Tormach about the issue and they promised to change the values. I'm still using an early version of PathPilot, so it may be that Tormach did indeed update the values in a later release.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 04, 2019, 01:03:31 PM

I'd have tackled the engine pillars in a slightly different way. I'd have done a helix all the way through in the centre and then incremented out, leaving about 0.5mm of stock. Then I'd have done a profile pass full depth to finish using a circular approach and retract. That way you avoid possible tool marks from multiple passes, and minimise tool deflection. I'd then take out the recess in one pass. For the outer profile I'd probably do it in two depth passes, again leaving about 0.5mm stock. Followed by a full depth profiling pass. I'd probably leave the tabs, but experience shows they're a PITA to remove without impairing the visual appearance of the part. At least I'd try and put them in places that mate with other parts so they're not seen.

Andrew

Thanks Andrew, that make sense as you get to use all of the cutter and as you say no risk of the various passes showing down the edges. I've done that with Cut2D and it does not make much difference to the suggested time though I did do the outer profile in 4 rather than two. May give it a run if I can find another bit of scrap Ali.
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 04, 2019, 01:37:56 PM
My PathPilot screen has 1mm as the maximum jog.  I also set jog feed rate to 40% of rapid.

That's useful to know. I contacted Tormach about the issue and they promised to change the values. I'm still using an early version of PathPilot, so it may be that Tormach did indeed update the values in a later release.

Andrew

PathPilot is derived from LinuxCNC.

With LinuxCNC, the jog increments are defined in the . INI file.

Go to the machines . INI file, in the [DISLAY] section you will find the INCREMENTS parameters listed. You can change and save the INCREMENTS parameters

I do not know if this works for Pathpilot as well as LinuxCNC. It is worth a try, you can always return to the original setup. :zap:

Mike

Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 04, 2019, 03:57:38 PM
I do not know if this works for Pathpilot as well as LinuxCNC. It is worth a try, you can always return to the original setup. :zap:

Me + fiddling with computer software internals =  disaster

Company IT managers have been known to turn white when I appear at their desk.  ::)

It's pretty windy here today, so I haven't gone out to the gliding club to rig my glider and measure the control deflections. Instead this afternoon I have updated my PathPilot to Tormach version 1.9.13 and lo and behold the metric jog steps have changed to slightly more sensible numbers. PathPilot is now on version 2.x, but to upgrade to V2 I need to buy a USB stick. Which will probably cost more to ship to the UK than the cost of the stick.  :(

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 04, 2019, 04:18:14 PM
A good practice is to place tabs on straight surfaces rather than curves.  Easier to clean up.  They don't need to be as large as yours.

For your engine parts, a no-tab solution would be to use stock thicker than needed.  The outer profile would then be milled so that it doesn't cut through.  Then fill the slot with an epoxy gel, wait for it to harden, and then face mill the back side to reveal the part.  The place in boiling water to release the epoxy.

Instead of epoxy, cut a pocket in some soft jaws that matches the output profile.  Then you can hold it securely when removing the bottom layer.  This is a good solution when making a lot of copies.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 04, 2019, 04:25:03 PM
@jadge

I'm running the 1.9 version myself on non-Tormach equipment and see no reason to update.  The CD version costs $100, and I doubt the USB stick would be more.

Notice that typing G20 in MDI will change the jog steps and DRO values to imperial; G21 back again.  Even when machining a metric part, I will often switch to imperial since I'm using an edge finder with a .200" diameter.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 04, 2019, 05:02:41 PM
This is the Cut2D version with the paths suggested by Andrew.

I have used smaller tabs but put them on surfaces that are not going to mate with others - the flat bottom and concave top therefor have clean machined mating faces. As I said the rest will get the corners knocked off with a dremel and files to get a better "cast" look and then be painted so my thinking is better to have the tabs there in this instance.

Gmv35vSUwtY
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 05, 2019, 08:42:55 AM
I'm running the 1.9 version myself on non-Tormach equipment and see no reason to update.  The CD version costs $100, and I doubt the USB stick would be more.

The USB stick for V2.x is $24.95; I've ordered one. Unexpectly the order went through with 'free' postage. Not sure I believe that! I had some trouble updating my profile (clunky website software) but it should be clear I'm outside the US. We'll have to wait and see what happens.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: gary.a.ayres on March 06, 2019, 12:27:05 PM
Jason -

the potential of this is huge.

Enjoy!
Title: Re: Going over to the dark (CNC) side!
Post by: DICKEYBIRD on March 06, 2019, 08:33:10 PM
@jadge00

 Even when machining a metric part, I will often switch to imperial since I'm using an edge finder with a .200" diameter.
After screwing up a part or 2 doing the edge finder switch-eroo, I recently started touching off my .200" E/F @ 2.54 mm.  Works great & no more miscues!
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 06, 2019, 09:17:04 PM
@jadge00

 Even when machining a metric part, I will often switch to imperial since I'm using an edge finder with a .200" diameter.
After screwing up a part or 2 doing the edge finder switch-eroo, I recently started touching off my .200" E/F @ 2.54 mm.  Works great & no more miscues!

One reason I do it the other way is when my stock isn't metric and I'm center finding using opposing sides, seeing the DRO at expected dimension + .2" gives a degree of confidence that I didn't screw it up.  Note that until the current engine build I'd never machined any metric parts, so habits are hard to break.
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 06, 2019, 09:54:12 PM
I use a Haimer Zero Master to pick up edges. Using one means you don't need to worry about imperial or metric units, simply jog until the needle is on zero.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 06, 2019, 11:58:00 PM
I use a Haimer Zero Master to pick up edges. Using one means you don't need to worry about imperial or metric units, simply jog until the needle is on zero.

Andrew

I recently bought a Haimer Taster.  The problem I've had with it is that I don't have a pendant and use the keyboard to job.  Accidentally hitting an arrow key instead of PgUp has resulted in destroying 2 of the probes at a cost of $50 each time.  So now it's confined to the Bridgeport.   >:(
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 07, 2019, 12:32:58 PM
For edge finding, centre finding and other work, I use a 3 axis touch probe and the LinuxCNC Probe Screen utility

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070333.JPG)

The probe is permanently mounted on a quick change toolholder and has a replaceable Haimer stylus.

The LinuxCNC Probe Screen utility will automatically find an inside or outside edge, corner, hole centre or bar centre at the touch of a button. The probe makes some beautifully choreographed moves to find the required edge or corner or centre, then moves to the clearance height resetting the appropriate X or Y coordinates to zero.

I crashed one of those expensive Haimer stylus tips while initially setting the search parameters. After that, I set the search speed fairly low ( 10 and 2 inches per minute) to be within human reaction times rather than having it whizzing about at the speed of light. The lower search speeds only add about 10 to 15 seconds to each operation, but is much safer.

I am very pleased with the touch probe and the  LinuxCNC Probe Screen utility. It works for me.

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 07, 2019, 12:35:43 PM

Accidentally hitting an arrow key instead of PgUp has resulted in destroying 2 of the probes at a cost of $50 each time.  So now it's confined to the Bridgeport.   >:(

I feel your pain. At the end of last year I broke the probe on my Zero Master. I managed to break mine on the Bridgeport by turning the handle the wrong way while in a rush to finish a job for work. :'(

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 07, 2019, 01:18:21 PM
Here is the tutorial, installation and user guide for the LinuxCNC Probe Screen utility.

https://vers.by/en/blog/useful-articles/probe-screen

If you are a LinuxCNC user, you will find this a very useful tool. It may also work with Pathpilot, but I have not tried that yet.

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on March 09, 2019, 01:02:02 PM

Murray,

Good to see you chipping in here, would definitely be interested in how long this would take you as having seen your machine in action it can shift metal at a fair old lick :o

I couldn't answer that without the CAD file of course but generally my approach is to select a modern cutter, look up the manufacturer's data for its feeds and speeds and use these as my starting point in Fusion to program the CAM. These are often a lot more aggressive than I'd have guessed and with a bit of testing you can get a feel for what you can actually achieve on your machine. Some of the modern cutters and inserts are significantly better than those of a decade or so ago, so it's worth trying a few out. They are often less prone to chatter and give higher removal rates (MMRs), lower cutting forces and better surface finishes. Generally I do a roughing operation followed by a finishing operation, rather than one single pass.

Currently Fusion doesn't report the spindle power required to support the resulting feeds and speeds so sometimes I've checked it won't exceed the available power by using one of the tool apps from Iscar, Sandvik etc. I believe Fusion will soon include an estimate of spindle power, so that extra step won't be needed soon. However, although I have only(?) 3kW available, that's enough for some pretty decent MMRs.

I always try to use as much of the flute length as possible, which is made easier by these modern adaptive toolpaths. It evens out tool wear and makes best use of adaptive toolpaths. My "big" machine is from the 1980s and cost as much as a house back then but the toolpaths at the time were very basic, manually coded rectilinear and circular things, whereas modern toolpaths can essentially follow almost any locus. The result is that the machine is now much more versatile and able to much achieve greater MMRs with less risk of breakage than it could previously. The original owner would be pretty surprised to see what it can do now!

To answer your question, once the part is programmed into Fusion CAM, the simulation gives a pretty accurate machining time estimate. In practice I find any significant difference is due to my manual tool changes rather than the machining itself.

One thing I learned fairly early on is the need to clear the (aluminium) swarf from the cutting zone to avoid it being "recut" when achieving high MMRs. Recutting can result in an inconsistent surface finish but above all it leads to the risk of swarf becoming welded to the cutter (ping!). Air and/or high flow coolant is the best way to avoid it!

Murray
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 09, 2019, 03:43:58 PM
I myself tend to be conservative with feeds and speeds as very few parts I make as a hobbyist are critical as to machining time.  A production shop may well decide to test a cutter to destruction, or at least run with spindle power meter at 100%.

Recently CamBam has added an operation for trochoidal pocketing and profiling, which is quite similar to adaptive paths.  Large depth of cut (use more of the side slutes), small stepover, and higher feeds.  This definitely improves chip clearance when machining aluminum as well.
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 09, 2019, 09:30:50 PM

Recently CamBam has added an operation for trochoidal pocketing and profiling, which is quite similar to adaptive paths. 

Hi Kvom,

I am considering changing over to CanBam. The latest documented issue, available over here in the UK, appears to be Issue 0.9.8 which does not appear to offer trochoidal pocketing. Can you tell me which version of CamBam I should be looking for which includes the trochoidal pocketing or whether it is an external add-on produced by an outsider.

Thanks

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 09, 2019, 10:31:41 PM
The latest is v1.0 "CamBam Plus".  While is says it's developmental, the reality is that most long term users have moved over from .9.8.  Trochoidal pocking and profiling were added by a user, and work quite well.

It is installed in the base product by copying the trochomops.dll to the Plugins directory.

The trochoidal profile and pocket DLL is available for both versions
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 09, 2019, 11:13:45 PM
Thanks for the advise to use issue V1.0 of CamBam and how to add the trochomops.dll to the Plugins directory. I will certainly give that a try.

In the mean time, do you have a copy of a small trochoidal pocket G-code file that I could use to test my Emco F1 mill? That would give me confidence in my machine's ability to cope with this type of high speed machining.

Thanks again for your help

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 10, 2019, 12:43:49 AM
Attaching the .nc file.  The pocket is 50mm square centered on 0,0, 5mm deep.  Tool is 1/4" (6.35mm) endmill.  Roughing clearance 1mm.

Toolpath is plunge to 5mm, then spiral out with a .2 stepover until the sides are reached,  Then each corner is milled with arcs of decreasing diameter.  I didn't know what material or tool, so feeds are notional.  You can do a global replace with appropriate values.  Here I specified only climb milling, so each arc is followed by a G1 to the start point of the next arc.  The program does allow bi-directional arcs, but I usually do it this way to allow chip clearance in aluminum.

If you'd like a better test, provide a DXF/tool spec/meterial and I can easily generate it.

FWIW, all of the aluminum pieces of the hummingbird were machined this way.
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 10, 2019, 01:00:50 PM
Due to our time zone differences, your trochoidal tool path file arrived overnight. I only got to play with it after all the mornings household chores were done.

My Mill runs under LinuxCNC control and is set up to machine in inches. Your toolpath are in metric units. I thought that could be a problem but fortunately LinuxCNC recognised the G21 (metric units) and made all the necessary conversions to inch measurements and displayed the trochoidal toolpaths accordingly. That's another first; something else learned.

I pressed the 'RUN' button with some trepidation and off went the machine. The spindle ramped up mto 4,000 rpm and machined air at a feed rate of 24"/ min (600mm/min). All appears to be working well, my mill can handle the feed rates and acceleration in both axes without apparent problem. However, the speed at which the tool moves arround is staggeringly fast, many times faster than I have ever machined anything before. That will take a bit of getting used to. The next thing is to try machining some metal.

Before I can do that, could you please generate a smaller test program, so that I can use the cutters and stock material I have available in the shop. I do not yet know how to attach a file to these posts, so I will have to use words instead. Please could you generate the tool path to make a rectangular pocket, again with 0,0 in the centre, measuring 20mm x 30mm and 6mm deep in aluminium, with a HSS, 5mm diameter three flute end cutting tool. My machine can go to 6000 RPM. I have air blast to clear the chips but no pumped coolant other than a can of WD40

Feeds and speeds must be critical to this high speed machining. What feed and speed calculator do you use? How close to maximum theoretical do you need to run the feeds? Is it OK to slow the feeds down or does that upset the way this high speed machining works?

Thanks again for your support

Mike

BTW.   my petite Colibri hummingbirds built a nest and laid some acrylic eggs.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1050478BB~0.jpg)



Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 10, 2019, 01:49:02 PM
High speed machining is a bit of a misnomer. It would be better to call the toolpaths constant engagement. To machine a pocket with a conventional rectangular toolpath at each step the cutter has to move across to the next path potentially at full width. So the DOC, and feeds, need to take that into account, despite the linear cutting being done at less than full width. The idea of the high speed paths is that the tool moves so as to keep the cutter engagement constant. Thus DOC, WOC and feeds can be set for those parameters, which are used for the whole machining cycle.

The term high speed machining really relates to maximising the metal removal rate by keeping the cutting parameters constant. It doesn't inherently imply running the cutter at high spindle speeds and feeds. Although of course that would normally be done in a commercial environment to minimise time. Any high speed toolpath will run perfectly well with slow speeds and feeds.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 10, 2019, 02:38:33 PM
Andrew,

Thanks for you excellent explanation. The concept of constant engagement toolpaths now make perfect sense. The knowledge that a high speed toolpath will run perfectly well with slower speeds and feeds is very reassuring. I guess the wear and tear on the machinery will also be considerably reduced at the lower rates.

It looks like the high speed, Trochoidal pocketing and profiling plug-ins to CaBam will be very useful addition.

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 10, 2019, 04:00:43 PM
Attached file as per your request.  I use G-Wizard for feed and speed.  I specified 20mm stickout and 50% roughing as additional inputs.  So feed rate is conservative.  Deflection of the tool is .01mm or 56% of breaking point.  Power is .038 kw, mrr 4.33 cc/min, estimated machining time 1:06.

The CB implementation doesn't allow for the non-cutting chords between slices to be generated as rapids, so I chose 1000mm/min arbitrarily.  You could do a global change of the g-code to reduce the speed or to replace G1 F1000.0 with G0.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 10, 2019, 04:38:26 PM
Thanks for the detail answer Murray and all the other posts which have been interesting to read. I have not had a chance to play with the KX3 this week (see Allman thread)  but hope to get some time soon.

J
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 10, 2019, 04:53:03 PM
Kvom, thanks for all your help and support,

66 seconds to demolish all that material...........and you say you have used a conservative feed rate!!!!!!!!

Off out to the workshop to try it for real :noidea:

Thanks again

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on March 10, 2019, 05:53:02 PM
Kvom,

I found I could only command the spindle to 5,400 RPM, so I slowed the feed rate to 80% to compensate.

I have never seen chips fly so fast and so far.

With is Trochoidal milling strategy, I can now achieve the same (once seemingly impossible feeds and speeds and MMR) as Andrew

Thanks

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: fumopuc on March 11, 2019, 01:11:24 PM
Hi Jason, I am following your learning curve with the Sieg CNC milling machine with great interest.
I have seen that you are using Vetric software for your first steps. This was also my first choice in 2013, when I have entered the dark side.
In April 2017 I have started the Fusion 360 adventure.
My regular process during the Fusion CAD learning curve was:
Creating a 3D model in Fusion followed by creating a DXF export for the CNC operation.
Importing the dxf file into the Vetric software and getting the toolpathes there.
At the end a very complicated process, but due to laziness or " I have done it always like this" I have used this process until end of November last year.
In my Christmas holidays I took the opportunity and tried the CAM Modul in Fusion360 seriously.
After doing the first parts, I have quickly recognized, that there is a huge and comfortable tool hidden behind this  "CAM" button in Fusion360.
So every possible minute was used to follow some Fusion360 CAM tutorials for learning.
The current status at this issue is, that since beginning of December 2018 my Vetric software is hidden in a dusty corner of my hard disc and I am afraid it will stay there for longer.
Finally is there only the question for me, why does it took so much time to find this way ?
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 11, 2019, 02:29:58 PM
For someone who uses F360, the built-in CAM makes a lot of sense. 

I use Solidworks which I get for free as a veteran, but the CAM packages that integrate with it are from 3rd parties and not free.  For that reason I use CamBam, which is relatively cheap for a lifetime license and which I find intuitive to use.  I still do the DXF export/import, but it's not overly complex.

Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on March 11, 2019, 04:18:47 PM
Achim, I got the vectric thrown in for free so that was really my only reason for using it and it seems quite simple to use. Although I draw in Alibre I had already looked at teh F360 CAM and will give that a go now that the machine seems to be behaving itself. I have already imported some STL files from alibre and done some simulated cuts to get curved surfaces (in Z) which you can do with a DXG file in Vectric Cut2D.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on March 11, 2019, 07:55:25 PM
FYI.  Cambam can do 3D surfaces and supports molds, where the positive surface is inverted in Z.  One of the most active members on the CB forum has a business making molds for fishing lures.

One thing that CB lacks at present, that other 3D CAM software may have, is "rest" machining.  The simplest type of 3D machining is a roughing pass for which one can use regular endmills, and the finish pass where a bullnose type cutter is needed.  What one would like ideally in some cases is two or more roughing passes where extra passes can use smaller tools to get close to the desired surface;  in other words, roughing the rest.  If that feature isn't present, then the machine spends much of the time cutting air on the second pass.

One needs to be careful with STL files found on the internet, as they may have problems that CAM programs can't handle.  There are several programs available for repairing the meshes on STLs.  Meshlab is one I've seen recommended.
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on March 19, 2019, 10:45:21 AM
The USB stick for V2.x is $24.95; I've ordered one. Unexpectly the order went through with 'free' postage.

I received the USB stick today. It was indeed free postage. But I got stung for £20.57p by ParcelForce for import duty and "handling" charge. Not so much force as darn right extortion.  >:(

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 07, 2019, 12:09:21 PM
It is all well and good cutting random shapes into bits of scrap to get the feel of things but nothing beats making more productive swarf. To this end I have been drawing up the next stationary steam engine for a while and was possibly going to get a couple of the parts laser cut but now that I have the CNC what better way to learn and be productive at the same time. The base "casting" of the engine will be a sandwich of 3 layers so I started with the bottom one, the upper is similar but has some different holes and bosses.


A Step file of the required part was exported out of Alibre and into a F360's CAM program where I generated the G-code for the holes and the actual shape as separate sets of code to make it easier for me rather than have to incorporate tool changes. I air ran the code first of all and then again into some PVC which showed up a slight error in heights which was corrected before cutting metal.

I started by clamping the stock onto some MDF and first ran code for eight 3mm holes, then after changing bits ran another code to enlarge four holes to 6mm. After that these holes were used to screw the 2.5mm thick plate to the MDF so that the clamps could be removed. After changing to a 6mm 3-flute HSS FC-3 cutter the button was pressed. I'm more than happy with what came out for my first proper part using CAM and the first time cutting steel and this plate is a bit gummy.

A couple of areas did not quite cut all the way through which was probably due to the scrap MDF that had been sitting around for a while but that just tore away. You can also see that I left some 1mm thick tabs to stop the larger pieces of waste moving about.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828461.jpg)

After a quick clean up

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828462.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Admiral_dk on April 07, 2019, 08:33:19 PM
Looking good Jason  :ThumbsUp:

I can't say that I'm surprised that you had a few places that didn't go all the way through ....

When I use the small CNC-Router at work, I use a template cut in high quality plywood that holds an Euro-Card PCB (160x100mm.) and even though the router itself has cut that pocket, I still get small variations.
This means that if I need to cut the PCB to a "strange" shape when all the rest of the milling is done, I let the cut go aprox. 0.5mm into the wood in the pocket (except the tabs) in order to ensure a clean cut-out.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 08, 2019, 01:33:44 AM
Does the single STP file encompass all sides of the part?  If so, how do you select the view and edges that encompass the machining?

In SolidWorks, I select a view of the part and export a DXF of that view.  For 3D surfaces, I export STL.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 08, 2019, 07:18:18 AM
Yes, it comes out as a complete 3D part in F360 so I can pick any feature as the geometry to cut. You can also select what way the part will be orientated on the machine if you did not draw it with the axis in the best position for machining. You can also enter the size of the stock so it knows what you are starting with.

This is the imported part showing the path of the tool and the second picture shows the end of the cutting simulation with the stock shown

This series of videos are what I used to see how to do it with F360

6FzbZNhey2w
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 09, 2019, 06:26:18 PM
I had a bit of time this afternoon so thought I would do the top plate, I did not air cut this time but did practice on some PVC before cutting metal.

First was to drill 15No 2.5mm holes with a split point stub drill which meant I could get away without spot drilling first

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828628.jpg)

Then a change to a 6mm stub drill to open up six of the holes

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828629.jpg)

Using these holes the plate was screwed down to the MDF below and clamps removed. Using a 6mm dia 3-flute cutter but carbide this time the profile was cut, not a bad finish on the bottom of the first pass.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828630.jpg)

All complete, the 6mm piloted holes that open out to the edge were enlarged to 8mm as part of the contour cut and I left tabs again to stop the waste flying about.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828631.jpg)

After a clean up with the bottom plate that I cut at the weekend.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828632.jpg)

I've stitched two videos together here, the beginning shows the first pass with the cutter at full width but 1mm away from the finished edge, second half shows the final full depth finishing cut, you can see the tool rise and fall where the tabs are located. The upload to Youtube seems to have added some high pitch noise which was not there at the time.

(https://www.youtube.com/watch?v=HWVk5nqtSXc)

I could quite get to like this CNC lark, next part has been through the CAM and will let me try some adaptive clearing cuts!
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 09, 2019, 08:33:50 PM
You could have added additional screw holes for the 3 extra pieces, and then avoided using and cleaning up the tabs.

Another hack that can save time is to use center cutting endmills for drilling.  In this case a 2.5mm tool could be used to spiral drill the 6mm holes.  That saves a tool change, but here you needed the 6mm tool for the next op.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 09, 2019, 08:44:34 PM
Funny enough I was thinking the same about the extra holes as even with a ctr cutting bit and a slow plunge the drop down after the tab was the one item where the cutter did not seem happy.

Not tried spiral cutting a hole yet but hope to give it a go soon.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 10, 2019, 12:43:16 AM
Spiral cutting is especially useful when you don't have a drill of the size you need.  Plunge milling makes a lot of sense for  roughing deep pockets; the Z axis of mills is almost always stouter than the X or Y, and there are no lateral forces to bend the tool.  In place where you might do chain drilling, you can plunge mill at less than a 100% stepover.

I usually make my tab length 3x the height.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 13, 2019, 08:14:55 PM
The adventure continues with this part which will be the bottom mounting flange of the cylinder.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828892.jpg)

First operation was to run the code which put the four 3mm holes into an oversize piece of 1/4" flat steel bar. I then put an offcut of aluminium into the vice and ran the code again but this time with a 2.5mm drill, the holes were then hand tapped and the two screwed together without removing the aluminium tooling plate from the vice.

With a 6mm dia 3-flute carbide cutter I first ran an adaptive clearing cut around the outside followed but a final contouring cut to finished size. I started off quite tame at 3000rpm and 150mm/min feed but found that could be upped as the flat bar cut a lot better than the steel plate I was cutting the other day.

The next part of the code had the adaptive clearing to form the 4 raised bosses, this again had been programmed as above but found I could go faster and ended up at 3900rpm and 225mm/min feed.

Again Youtube has added some high frequency noise but you can see the first cut around the outside where the DOC varies as I only rough centered the work followed by 3 clips of the top clearing at various stages.

dd4sHBimQ-g
Final job was to skim the bottom off, final size will be done after silver soldering the assembly together.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828889.jpg)

Intention is to have a 20mm block between the bosses so a quick test with an ARC 10-20-40 block to see what the fit is like

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828890.jpg)

Can't get much better than this

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/828891.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 14, 2019, 01:12:22 AM
Why is the return move on each clearing cut so slow?
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 14, 2019, 07:34:52 AM
Why is the return move on each clearing cut so slow?

Because I still have a lot to learn :-[

I have now found the box where the "non engagement feed rate" can be set, looks like it defaults to the cutting feed rate so I have now increased that and will know it needs to be done the next time I use the Adaptive.

Out of interest do you set the speed of these return movements the same as the rest of your rapids or less?

J
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 14, 2019, 10:43:02 AM
Over on ME Forum I have also been advised to set the adaptive to cut in both directions which makes it quicker still, I had just been using climb cutting.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 14, 2019, 12:32:06 PM
The bi-directional feed rate is good, but for aluminum I use only climb.  That allows air blast to clear any chips and prevent welding during the non cutting move.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 16, 2019, 07:13:32 PM
To finish the sandwich construction of the engine base some form of filling was needed and as I have quite a few off cuts of Corian I decided to use that rather than metal.

The sequence was much the same as the top and bottom plates but I tried out peck drilling for the 3mm holes as they were quite a bit deeper than before, I could have gone faster with the retract speed and not lifted so far out of the work, drill was running at 5000rpm.

I used a chip breaker feed for the larger holes, you can't see it that well on the video but can hear when the drill pauses the feed which if I was drilling steel or Ali would shorten the swarf, dropped down to 1000rpm on the 6mm and 7.8mm holes.

Finally machining the contour where you can see the tool ramp down and then start cutting in 2mm deep passes before it starts to get lost in the swarf which is when I stopped filiming and got the vacuum running. The 3-flute Carbide cutter romped through this at 5000rpm and 350mm/min feed.

QekBlcNrIqI

I did not use any tabs this time as the material was thicker than needed, bottom milled off afterwards.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829128.jpg)

Quite pleased with the cut edge, no sign of cutter marks when held upto the light, this was a full depth finishing pass

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829129.jpg)

I used a 50mm face cutter to thin the work down to 10mm moving the clamps to complete the ends, only downside to working with Corian is the mess.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829126.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829127.jpg)

I'll bond it all together with JB Weld but that won't be until the bearing supports have been fabricated and silver soldered to the top plate but could not resist a quick trial assembly.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829132.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829130.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829131.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Admiral_dk on April 16, 2019, 09:46:33 PM
Nice progress so far and I like the combination of the different materials  :ThumbsUp:
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 18, 2019, 06:49:00 PM
A post on another thread brought up the subject of the "Star Wheel" used on the Alyn Foundry "Sphinx" engine which is an alternative to timing gears and operated the exhaust valve on alternate strokes. A casting is supplied but I happened to mention that  it would be something worth trying to cut on the CNC. Well that was all it took to get me trying it out.

Video firstly shows the adaptive clearing, I speeded things up 20% after filming so that was a 6mm Carbide 3-flute cutter at 3600rpm, 150mm/min, full 8mm height cut with a conservative 0.25mm DOC. I went with Andrews suggestion of cutting both ways which reduced the time quite a bit. It was cutting very nicely and I did not bother with brushing on anymore suds which only seemed to make the swarf stick to the work.

There is then a clip of a 4mm dia cutter clearing further into the internal corners which went well but during the final contouring cuts it went pop which almost made me go poop. It was a cheapie and at a cut height of 2D I was probably asking for trouble. I had drawn in a corner radius of 2.1mm but that probably should have been more.

Video ends having reverted back to the 6mm cutter for the final contour cuts which I slowed down so that it would not chatter in the corners.

ypy7-kxYlIQ
This pic shows the star wheel after the first clearance cuts, you can see the faceting of the curves.
 
(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829227.jpg)
 
This is after all the milling where the curves flow better. Interesting to see the three height bands left by the tool, although it has not done much they show the wear from the 2.5mm plate, the 1/4" flat bar and the best finish at the top which can be seen better in the video is unused edge.
 
(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829231.jpg)
 
All that remained was to file out the internal corners, casting shown alongside. Just need to put it away somewhere safe and resist all temptation to do more on this engine for a while.
 
(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829232.jpg)

Simulation of the cutting

DIVmWdXQ8d8
Title: Re: Going over to the dark (CNC) side!
Post by: Johnmcc69 on April 18, 2019, 07:03:03 PM
 :ThumbsUp:
 Pretty cool stuff Jason! Modeling the parts, creating the program, & watching it work, is pretty exciting.

  :popcorn:

 John
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on April 18, 2019, 10:07:17 PM
That is the type of part I prefer to make from stock vs. the casting as well.

Thoughts:  The big nut on top meant that your tool stick out was higher than it needed to be.  Generally you want the collet to be clamped as close to the flutes as possible and the profile cut to be as high on the flutes as possible.  4mm mill got deflected too much.

According to G-wizard, if the stickout were 12mm, a DOC of .25mm would allow a feedrate of 800mm/min in 6061 for a MRR of 1.68 cc/min.  But a DOC of 40% of tool diameter (2.4mm) with a feed of 213 mm/min has a MRR of 10.25.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on April 21, 2019, 05:26:56 PM
Just a small item today in the form of an elliptical gland flange, used an aluminium specific cutter as they also work well in other non ferrous metals and a split point Dormer stub drill for the 2mm holes.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829424.jpg)

I cut another star wheel but took the different route of drilling 2mm holes at the root of all the internal corners which made filing to final shape a lot easier than leaving the 2mm radius from the 4mm cutter.

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/20190419_185827_zpsnjjbrvtz.jpg)

(https://oimg.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/20190419_192428_zpsrgthoqk1.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 04, 2019, 07:03:50 PM
I've not had the need to do much on the KX3 over the last couple of months but thought I had better blow the dust off it and see if it (and me) could handle something a bit more complicated. I have been drawing up a 24mm bore single cylinder 4 stroke with side rods loosly based on a design published in Practical Mechanics in 1938 with the intention of CNC machining the two crankcase halves.

So with a piece of 1" 6082 T6 aluminium mounted onto a holding block I loaded up the code and let rip.

The first 3 clips in the video show the 3D adaptive clearing which was done using one of ARC's 6mm 2-flute aluminium specific HSS cutters, I was in two minds whether to use this as I had noticed a bit of chatter when using it in the manual mill in the past particularly as I wanted 27mm sticking out of the collet so that would not crash into the work but after a chat with Ketan a while back I decided to give it a go. 5000rpm, 8.5mm height of cut (1/3rd stock height) 1mm depth of cut, feed rate of 300mm per min giving achip load of 0.03mm which was just right and did not need altering. 0.5mm material left for finishing

4th clip is the same as above except height is reduced as the surface was between the two 8.5mm increments, this is where a tiny amount of chatter could be heard on the lighter loaded cutter.

Clips 5-7 are the 3D contour which was used as the sides of the crankcase all have draft angle rather than vertical sides. I used a 2-flute carbide 6mm cutter with 1.0mm corner radius. Again run at 5000rpm, with a 0.5mm stepdown and the DOC was the 0.5mm that was left, feed 400mm/min. In hindsight a 4 flute cutter would have been better as the amount of swarf was not great so the 2-flutes extra clearing capacity was not needed and then I could have fed faster.

Clip 8 Spotting the bolt holes with a 5mm HSS spotting drill at 5000rpm

Lastly drilling the 3mm holes with a Dormer A002 split point drill at 5000rpm and using a pecking cycle to clear the swarf.

IDQwAdshtOQ
(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/834211.jpg)

The bit of flash around the bottom is due to me doing the CAM for 25mm stock but using 1" , there are a couple of things I will alter slightly for the other half but overall I'm quite pleased with how it turned out. particularly the tapered surfaces as I was expecting them to need more fettling but they are quite smooth and will just need a quick rub with emery before blasting the surface to get it to look like a casting.
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on July 04, 2019, 09:45:44 PM
Looks like you are getting the hang of this CNC stuff. Well done.
Remind me again who's software you are using. Is it Fusion 360 for the CAD/ CAM and Mach 3 for the machine control?
The draft angle slopes look good. Can you go curvy slopes or just straight angles?
Mike
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 05, 2019, 07:13:45 AM
I draw with Alibre Pro and then export a STEP file into F360 to generate the code and use Mach-3 on the machine, I wanted to get the part done before Saturday so you could look it over and point out any things I could try differently.

Yes the CAM will let me do all sorts of shapes and I should probably have done a finer stepdown on the curved section under the cylinder mounting flange so will see if I can add that to teh other half.

Is this curved enough for you?

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/829660.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 05, 2019, 12:40:42 PM
Looks pretty reasonable Jason! Takes a while to get used to creating the toolpaths, feeds and speeds, heights etc but in the end I find I can do things you simply couldn't make on a manual process and even with the extra time for programming the CAM, the overall time is a lot less for those that you could - there's considerably less faffing about with setup between ops.

One real benefit of Fusion is the fact that the CAD and CAM are closely integrated which means you can quickly and easily alternate between the CAM toolpath generation and the CAD model design and back again. The reality is that when you come to programming up the CAM, you often find you want to finesse the CAD model. Moving only one way (via STP format) is very limiting. Just saying....

One neat and powerful feature of Fusion CAM is the ability to save the part-machined output of one CAM setup as a mesh (STL) file and then reuse that as the stock for the next setup eg when you turn the part over to finish the other side. When you run the toolpath simulation, you can right click on the resulting machined stock and "save as" an STL. Then "insert" it into the CAD environment - this creates a body. When you do the next CAM setup, you can select that body as your stock and Fusion will know where what is really in front of it. Works really well and avoids "surprises".
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 05, 2019, 01:18:50 PM
Thanks Murray, good to have your input which I've missed from ME

I noticed early on when watching a couple of Lars' videos that he jumped back into the CAD to make an alteration, as you say easy when it is all in one place and would be useful as the final design is tweaked. What I need to look into now is using the same set of operations for the other half which is basically a mirror image rather than having to enter them again though the practice will be good for me anyway.


I don't have any air/lube set up yet so tend to stay by the machine so probably not as productive as leaving it to it's own devices but at this stage I'm happy to watch and see if it is doing what I hoped it would. I've not yet tried anything with a second setup but may be tempted to at least do the main cavity inside the crankcase as that has no critical surfaces but either way will bore the bearing holes in the lathe with the two halves fixed together to ensure things line up 100%. It would be easier than a second setup after turning to bore the area around the cam shaft.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on July 05, 2019, 01:40:49 PM
(http://One neat and powerful feature of Fusion CAM is the ability to save the part-machined output of one CAM setup as a mesh (STL) file and then reuse that as the stock for the next setup eg when you turn the part over to finish the other side.)

This is called "rest" machining; you can program to the rest of the part after a roughing op.  That's something I don't have with CamBam.  One use of this feature that would be very welcome is multiple roughing passing.  Large tool to start and smaller tool afterwards, to save machine time.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 05, 2019, 01:45:23 PM
(http://One neat and powerful feature of Fusion CAM is the ability to save the part-machined output of one CAM setup as a mesh (STL) file and then reuse that as the stock for the next setup eg when you turn the part over to finish the other side.)

This is called "rest" machining; you can program to the rest of the part after a roughing op. 

Fusion seems to do that anyway, for example on that part i first did the adaptive clearing to leave 0.5mm and then without saving or altering the setup did the 3d contour and it just removed the remaining 0.5mm, then did a couple of parallel cuts to do the flat surfaces the contour missed. Drill started from that flat surface.

EDIt, just tried it with two sizes of cutter and there is a "rest" setting that comes up when doing the clearing cuts which has option such as"from stock" or "from previous machining" but that is with the part held in the same position.

Title: Re: Going over to the dark (CNC) side!
Post by: jadge on July 05, 2019, 05:46:51 PM
In my CAM system, for 2.5D, it's called re-machining. The key point is that one can pocket or profile using a large cutter and then re-machine only the corners using a smaller cutter. So overall machining time is considerably less. In 3D things get rather more complicated, in name anyway. There are several operations, such as re-roughing or valley machining, that all add up to the same thing. Using a smaller cutter to remove just the material left in awkward corners or fillets.

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 05, 2019, 07:37:38 PM
Yes, "rest machining" relates to a series of operations within one "setup". If you turn the part over, you create another setup. My comment about saving the part machined stock as a model for the next setup is relevant when you come to machining the rest of your engine block eg from a different direction.

Dunno how you are supposed to insert an image into this thread but I've attached a view of a part machined component from one setup which has been used as the stock for the next setup. This worked very nicely.

One of the best improvements I've made to my machine setup has been the addition of a proper electronic touch probe. I got an old Renishaw probe from ebay which connects into my Acorn controller and allows me to pick up features within 5um or so, which is better than my machine can machine to. It means I can return the part to the vise and finesse dimensions etc by tiny amounts (10um increments). It's also invaluable for picking up the part origin on the next setup. With thought, you can choose a feature that was machined in the previous setup and use that to transfer your coordinate system without introducing an unintentional offset.
Title: Re: Going over to the dark (CNC) side!
Post by: RonGinger on July 06, 2019, 02:38:25 AM
Wow! what a finish on that part. Can you tell us about the tool used, speeds and feed, and the type of machine it was done on. It must be a very rigid machine.
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 06, 2019, 12:56:34 PM
It's a 1983 Shizuoka AN-S fitted with Centroid Acorn controller and CNCdrives DC servo drives. When fitted with these modern controls and running modern tools and toolpaths, even old machines are capable of some amazing output. It's bigger than a Bridgeport but is a turret mill too.

I find that good quality modern tooling is easier to drive (variable helix, sharper edges, lower forces, less chatter) and produces a better surface finish than classical cutters of a decade ago, in the same way that lathe tooling continues to progress. I have some cutters with lapped edges that produce a mirror-like finish in aluminium but they are razor sharp and lethal to handle. The variable helix cutters are particularly good for machining steel and I really like the YG-1 V7 range (stocked by Cutwel in the UK). They are on "3 for 2" offer at the moment...

The cutter that did most of the work is a 10mm three flute uncoated long series end mill from APT Tools, although Ketan's are probably just as good. I tend to use big step downs (to use as much of the flute length as possible) and use the adaptive toolpaths where possible. The term "optimal load" refers to how wide the cutting zone is relative to the cutter diameter, so a typical 20% would equate to 2mm here. I always use climb milling to avoid rubbing and get a better chip. It also tends to chatter less. And I try to avoid using the end of the end mill to do a finish pass, if at all possible using the side of the cutter instead.

It's worth exploring what your machine is capable of, either by being prepared to sacrifice a couple of cutters in the interests of science or by being human and accidentally overdoing it from time to time without bottling out. Often I have found that spindle speed is the limitation that prevents me following the manufacturer's advice on feeds and speeds for a given cutter. Chatter tends to happen when I have excessive overhang or am taking a heavy cut in thin stock.

For aluminium I use flood coolant or WD40 but above all, clearing the swarf is critical, to avoid recutting and tool welding / breakage. Like Jason, I attend closely to avoid mishaps. If I had a fully enclosed machine with high flow coolant, perhaps I could leave it unattended. In my dreams.

If you have a few idle moments, I posted some videos of various operations, including a couple of "moments":
https://www.youtube.com/channel/UCo5vJdD8q3xQ0xCrZfi9dIA (https://www.youtube.com/channel/UCo5vJdD8q3xQ0xCrZfi9dIA)
Title: Re: Going over to the dark (CNC) side!
Post by: RonGinger on July 06, 2019, 02:23:26 PM
Thanks, that is pretty impressive. My modified JET knee mill has never come close to that kind of finish.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 21, 2019, 05:34:14 PM
Nothing too adventurous this weekend I just used the mill to contour and drill the square cylinder flange for the Little Midget engine.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190721_085620_zpsk79bxzxb.jpg)

Must be doing something right a sit fitted onto the two crankcase halves OK.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190721_090733_zpsi6gs32ep.jpg)

Unfortunately word has got out that I have the CNC and I got a call from my brother asking if my new toy tool could make a replacement part for a lamp my Niece had bought for when she goes off to Uni in the autumn, couldn't really say no.

URk_F6GPeUI
Title: Re: Going over to the dark (CNC) side!
Post by: vcutajar on July 21, 2019, 08:41:48 PM
Always love to see small CNC machines in action.

Vince
Title: Re: Going over to the dark (CNC) side!
Post by: Vixen on July 23, 2019, 10:39:17 PM
Today was a hot day and I spent all afternoon working the Emco Compact 5 CNC Lathe. I had a batch of 30 small diameter (0.125", 3.175mm) brass rods to make, which needed to be a tight clearance fit in a ceramic bead. When I started the workshop air temperature was a pleasant 21*C, the air temperature rose to 30*C during the afternoon. The CNC stepper motors were noticeably hotter than normal and must have contributed to the workshop temperature.

I machined the brass rod to the required diameter in small diameter increments followed by three spring cuts to produce a consistent final diameter. I noticed that every hour or so, as the temperature increased; I needed to correct the final diameter by a thou (0.001") to continue to achieve the required tight clearance fit. I put his down to thermal expansion of the whole lathe structure, due to the higher than normal ambient temperature and the hotter running stepper motors.

Technical tip: The normal axes convention for a CNC Lathe is Z axis for length and X axis for diameter. I find this can lead to confusion and possible errors if you frequently switch between the CNC mill and the CNC lathe. To avoid this pitfall, I have a second set-up for the lathe, based on mill practice. I use the X axis for left/ right (length) movement and the Y axis for fore/ aft (diameter) movement. I find this mill like set-up on the lathe to be far more natural and less prone to error. An added advantage is being able to use the same CAM software to produce tool paths for both the mill and the lathe.

Mike
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 28, 2019, 01:15:04 PM
Another epic adventure to the very dark side with some Cast Iron needing reducing to swarf, one additional advantage of using the CNC is you don't get dirtly which seems to put some people off using this material

After a slight glitch with the latest Alibre update which was very promptly dealt with by their forum and support on a Saturday morning I was able to do the CAM for the cylinder head. The stock was roughed out on the lathe from some 50mm CI bar and two holes drilled and tapped where the valve holes will eventually be bored and I used these to hold it to a block that could be held in the vice.

Video starts off with the adaptive clearing with a 6mm 3-flute carbide cutter, 4500rpm, 300mm/min feed. 5mm high cut x 1mm DOC. I set the  CAM to cut in 5mm deep increments to use the edge of the tool and it then works back up in 1mm steps to cut to the specified 0.5mm that is left for finishing. Bit of chatter from the tool when cutting conventionally but it's happier climb milling. Same tooling for the finish contour at the top of the valve guides as I wanted a sharp internal corner.

Then onto the 3D contour using 6mm 4-flute R1 corner radius carbide bull nose cutter, 4750rpm, 400mm/min feed and 0.33mm stepdown, could have done finer on the more horizontal surfaces but happy to do a bit of file work to get that "cast look"


Finally Drilling with 3mm split point stub drill 2500rpm.


It's about time Jo diverted some of her casting fund to a CNC machine, ideal for knocking out multiple Anzani Heads :LittleDevil:

A3ymCvgD5-s
Title: Re: Going over to the dark (CNC) side!
Post by: Johnmcc69 on July 28, 2019, 02:40:01 PM
 :ThumbsUp:
Very nice Jason!

 John
Title: Re: Going over to the dark (CNC) side!
Post by: fumopuc on July 28, 2019, 03:05:32 PM
Hi Jason, seeing your last video, it looks like that Fusion does not mil a circle, it looks like several small faces added.
Did you try already the tick in the box at "Glättungsfilter" ?
I know it is German, but I am sure you will find it in your Fuison immediately.


Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 28, 2019, 03:53:28 PM
That's "smoothing" in the English language version. It's present as an option in most of the Fusion CAM operations but for some reason it's not set by default. I always try to remember to enable it.

The adaptive toolpaths are roughing operations, so to get the best finish, you need to select a Contour operation to follow the Adaptive - and remember to set smoothing! Sounds as if Jason did use a Contour toolpath at the end but it's not clear if that was applied to the surface(s) you were talking about.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 28, 2019, 04:41:32 PM
The first 5mins are adaptive clearing (roughing) cuts leaving 0.5mm material as Murray says and these do tend to leave a "faceted" edge which can be seen on the top small diameter of the valve guides, around the sloping spark plug surface and also the lower flange particularly on external curves where the tool leads in and leads out. Not really visible in the concave "counterbores" where the holes go

At about 5mins into the video it starts on a contour where the cutter spirals down around the tops of the valve guides and you then cannot see the facets, you don't get to see any remaining contour cuts on the above mentioned surfaces, just some around the elliptical shaped section

I did not have smoothing on for the contour cuts as it did not seem to make a difference on the simulation both in appearance and time taken to cut. Looking at the finished part under a magnifying glass I cannot see any signs of facets (flats) just the slight ripple from the tool which is the same on the flat flanges either side, can't feel anything either.

If I get a chance I will do a test piece with smoothing on and off and report back
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 29, 2019, 06:03:32 PM
There's some pretty useful background on smoothing in Fusion 360 CAM here https://forums.autodesk.com/t5/fusion-360-manufacture/understanding-smoothing/td-p/6636189 (https://forums.autodesk.com/t5/fusion-360-manufacture/understanding-smoothing/td-p/6636189) if you are interested / have a few spare minutes.

If you prefer sound and light, John Saunders did a short video on the subject:
kSI8FaNpO8k
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on July 29, 2019, 07:04:02 PM
Thank's for that Murray, I opted for the video.

If I do as he shows and click to show the points along the tool path I can see that I just have a point at the start of the circular flange and one at the end so it is moving in an arc not a series of facets, then cuts a short straight cut out to the oval flange, arc around the corner and then straight along the face of the oval flange. This is confirmed by looking at the code with is all G2, G1, G2, etc

So no need to use smoothing on these finish contour cuts.

J
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on July 29, 2019, 07:38:58 PM
Indeed - nothing to be gained there. It comes down to the fact that machine moves are a series of either straight lines or circular arcs (or both together, aka helices). Once you understand that, you have an idea where smoothing could benefit you and where you would be wasting your time.

The main source of noncircularity on my work is the residual backlash. Even with reasonably minimal backlash on my machine (perhaps 10-20um on a decent cut), I see a witness mark where the X or Y axis changes direction. Although some controllers claim to have backlash compensation, the reality is you can't get rid of such a nonlinearity in the plant model with smart control software and you have to live with it.
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on July 29, 2019, 11:55:28 PM
In CamBam, the Cam I use, splines need to be first converted to polylines, and then the equivalent to Fusion smoothing is to do an arc fit with a specified tolerance.

I suppose Fusion can import DXF files, and some CAD programs may generate polylines or arcs with many small segments.  The same smoothing techniques are applicable here as well to reduce the number of segments.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 17, 2019, 08:35:27 PM
next part for the Midget engine that could be done on the CNC were the rocker arms which were cut on the opposite ends of a bit of 1.5" x 0.25" flat steel bar.

First a clearing cut all round with 6mm 3-flute cutter at full depth plus 1.1mm to give the later 1mm R corner mill clearance, this then rises up and roughs out the top contour in 0.5mm steps.

Followed by a 4mm dia 4-flute 1mm R corner cutter working it's way down in 0.2mm steps on the flatter surfaces then 1mm as it gets to the vertical.

Side shot of the work so far.

Then a shot after it was sawn off the bar and held in machined jaws to bring down to 5mm thickness in the X3

Then back with the 4mm bit to contour the other side again held in the machined jaws

Finished parts after a lick with a needle file.

kO9qIaB77vA
Title: Re: Going over to the dark (CNC) side!
Post by: vcutajar on August 17, 2019, 11:39:58 PM
Nice  :ThumbsUp:

Vince
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 21, 2019, 04:14:34 PM
Thank's Vince

I found a bit of time to run the CAM for some cams. In the past I would either have used CamCalc with multiple offsets of the mill at angular increments around the cam or used the inside out boring head method particularly on cams like this with a flank radius. Both of which take a while to setup and in the CamCalc case a long while to cut.

This time with 0.4mm deep x 5.5mm high roughing passes and a slightly slower fed 0.2mm DOC finish pass on the silver steel the cam was done in 2.30secs mins with no need to do any blending with files after. I can't see me wanting to go back the the old ways of doing things.

LymJwG9oBi8
Title: Re: Going over to the dark (CNC) side!
Post by: tangler on August 21, 2019, 06:41:34 PM
 That's the way to do it.
 :ThumbsUp:

Rod
Title: Re: Going over to the dark (CNC) side!
Post by: Muzzer on August 21, 2019, 07:57:46 PM
I was impressed by the idea of completing the operation in 2.3 seconds. However, 2.5 minutes is still pretty respectable!

Nice result.
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 21, 2019, 08:10:56 PM
Did I not say the video was in slow motion :-[
Title: Re: Going over to the dark (CNC) side!
Post by: Admiral_dk on August 21, 2019, 09:13:42 PM
Very nice Jason  :cheers:

I can't remember if you have a fourth axis for your CNC, but if you do, I'm curious about doing the same at 90 degree to what you just did - why - well if you need several cams on the same shaft, it could soon be necessary ....

Best wishes

Per
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 22, 2019, 07:15:37 AM
I only have 3-axis but the machine comes with all the boards and drivers for a 4th axis, I also have a Sieg rotary table here so would just need to fit a stepper motor and then plug it into the socket provided at the back of the machine.
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on August 22, 2019, 08:53:39 AM
I can't see me wanting to go back the the [sic] old ways of doing things.
Blimey, that's a handbrake turn from what you wrote recently on another forum about willy-waving rights when doing it manually.  :o

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 22, 2019, 09:11:10 AM
I'm happy to not wave it about as much.  ;)

Having done it both ways I still think those who make their cams manually deserve a right to wave and I would probably still do it for a one piece camshaft with multiple lobes but seeing as I now have the machine it would be rude not to make use of it for certain jobs.

Though I wonder if a short cam could be cut vertically using something like a tee slot cutter to do several lobes :thinking: Might have to put the Hoglet cam into F360 and see if I can do it. Would certainly make it a lot quicker to play with different cam profiles and timing if you were after performance from an engine.
Title: Re: Going over to the dark (CNC) side!
Post by: jadge on August 22, 2019, 09:23:52 AM
I'm happy to not wave it about as much.  ;)
Better nip over to the other forum and correct the blooper in your reply to ChrisJ this morning then. I can't imagine many people wanting to hit it with a lump hammer.  ::)

Andrew
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 22, 2019, 09:52:55 AM
I can't imagine many people wanting to hit it with a lump hammer.  ::)

Certainly won't do any good to the hardening :o
Title: Re: Going over to the dark (CNC) side!
Post by: kvom on August 22, 2019, 02:07:32 PM
I have mentally designed a system to machine cam lobes with a 4th axis, but it requires programming.  The idea is to draw the lobe profile in CAD, and then break the polyline into some number of straight lines.  Each line is defined by the points on its ends, and the pointlist is somehow exported from CAD.

The program code then calculates for each line the A-axis angle needed to bring it horizontal plus the Y and Z axis values  of the line's center once rotated.  Then one can generate G1 moves consecutively for each segment.  If roughing pass(es)  needed, just run the same code with Z values larger than final.
Title: Re: Going over to the dark (CNC) side!
Post by: tangler on August 22, 2019, 03:00:27 PM
Nobody is much impressed by willy waving (not in my case anyway).  Although I have a proprietorial fondness for CamCalc,  drawing the profile in CAD and then getting the machine to cut it is much less tedious than Manual Numerical Control.  All our skills get superseded - I was really proud of the analysis and plotting routines I used to write for Thermal Analysis and then Excel came along  >:(
Rod
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on August 28, 2019, 06:55:09 PM
Nothing too exciting on the machine this week so I did not take a video. Firstly did the eliptical flange on the end of the stock that will form the carb body.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190825_143056_zpslbfc1usl.jpg)

Then used that to hold a bit of 1.5mm stainless steel that will be the exhaust flange

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190825_143018_zpsruta8pzj.jpg)

Rest of the carb was done with conventional tools and has a throttle barrel rather than the straight through venturi type.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190828_141503_zpsdfbut0bg.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on September 05, 2019, 05:20:25 PM
Today we have a Conrod which may be of interest to Rod (Tangler)

2014 (HE15) aluminium, I made up the two parts on the manual mill, screwed them together with sacrificial brass screws and then popped in the two holes and while I was at it made a plate to hold it on for machining.

3D profile done with a 4 flute 6mm dia cutter with 1mm corner radius so no stress risers at 5000rpm, modest feed of 300mm/min. Then change to a 4mm cutter again with the 1mm radius to do the recess in the middle. Runtime was 12mins for the two ops plus 2 x 1mins for the other side.

Quite pleased with how it came out.

XGB7FHfdGsE
Title: Re: Going over to the dark (CNC) side!
Post by: tangler on September 06, 2019, 01:52:27 PM
That's what I was trying to.  Sadly my mill won't  communicate with a PC at the moment and I've  already wasted too much time on it.  I need to get on with the Farm Boy.
Cheers,
Rod
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on September 25, 2019, 08:20:12 PM
Time to make a bit more swarf or more precisely 86.5% swarf and 13.5% left in the part which is the ignition bracket for the Midget engine.

6082 Aluminium, 3-flute carbide 6mm dia, 55deg helix, uncoated

Facing 5000rpm, 330mm/min feed, 0.5mm DOC, 5.0mm WOC to remove the saw marks and level the top

Adaptive 5000rpm, 330mm/min feed, 5.0mm height of cut, 1.0mm stepover. The cutter was not so happy with conventional cutting causing a bit of vibration in the chip tray but OK climb cutting.

Contour 5000rpm, 330mm/min feed, 3mm height of cut, 0.5mm depth

Helical bore 5000rpm 330mm/min, 0.5mm pitch. First time I had done this and very happy how it turned out. The hole was rough bored with a 0.5mm pitch followed by a 0.25mm full depth finishing cut and then a spring pass at the same diameter.

Finished off with conventional machine and hand tools.

cZrL3pbNxis
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on October 13, 2019, 12:31:34 PM
When I first entered the dark side I was hoping that there would be some light on the other side. Well today the light shone brightly.

With all the Midget parts finished, 57 individual items plus a further 30 custom made nuts, screws etc.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20191005_182555_zps1sw3xgzj.jpg)

It was time to see if I remembered how it all went back together. Valve timing was set by eye while turning the engine over slowly watching when the valves opened and closed. A little more oil than the normal running level put into the crankcase, some Colemans with a drip of 2-stroke oil into the fuel jar and give it a go. I got some pops straight away and with a bit more retardation of the timing it fired into life with a couple more pulls of the cord.

Throttle is by rotating the jam jar fuel tank but quite slow to react due to sizeable flywheel, advance & retard are a better way to set the speed which I had always intended was going to be for looks and noise rather than outright speed and performance.

Had to turn it off as I need to get that curtain cord back before anyone notices it is missing. Just needs a bit of colour to finish it  :pinkelephant:

CNndvvWaN-g
Title: Re: Going over to the dark (CNC) side!
Post by: vcutajar on October 13, 2019, 01:17:09 PM
Great runner Jason.

Looking forward to your next project and more CNC machining videos.

Vince
Title: Re: Going over to the dark (CNC) side!
Post by: Dave Otto on October 13, 2019, 05:01:11 PM
Nicely done Jason, she runs great!

Dave
Title: Re: Going over to the dark (CNC) side!
Post by: Admiral_dk on October 13, 2019, 07:30:29 PM
Nice Jason and a good runner and starter too  :ThumbsUp:

There is one part that stick out in the family picture for me - the upper leftmost next to the O-ring ....
To me it looks like it has something to do with oil .... a breather perhaps ?
Title: Re: Going over to the dark (CNC) side!
Post by: Jasonb on October 13, 2019, 07:46:33 PM
Thanks for all the comments

Yes it is a breather, the one in Popular mechanics had a big ugly thing off to one side but I went for something smaller and centrally placed. Also doubles as the oil filler and I added the brass screw lower down as level/drain

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/Midget/20190929_113444_zpsekloib6o.jpg)
Title: Re: Going over to the dark (CNC) side!
Post by: Kim on October 13, 2019, 10:24:32 PM
Very nice little engine, Jason!
Kim
Title: Re: Going over to the dark (CNC) side!
Post by: Art K on October 15, 2019, 05:04:58 PM
Jason,
Great build on that Popular Mechanics engine. They are right, I missed the build article. Is it a Midget because its smaller scale than original? :lolb: Great job on the cnc it was nice to see it in action.
Art