Author Topic: CNC 4th axis up grade  (Read 3360 times)

Online fumopuc

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CNC 4th axis up grade
« on: February 11, 2021, 01:54:52 PM »
Hi everybody,
in autumn last year I have spend some money to up grade my little Proxxon CNC with a 4th axis.
The very first attempts has been made immediately, first to understand the basics.
A first and easy g-code was available very quick.
[youtube1]https://youtu.be/nqd1UylGMVo[/youtube1]
Also the first chips has been made very soon.
[youtube1]https://youtu.be/kCUU9NP9eAw[/youtube1]
Than the time for further investigation could not be find shortly.
Before Christmas I have started another learning curve for 3D machining in combination with the 4th axis.
This part was the next attempt to understand better what is going on here.
[youtube1]https://youtu.be/0jazD0Ep1Qc[/youtube1]
I have been not so happy with some parts of the result and started a measurement of the rotating axis.
Basically this behavior of the axial bearing of the table has worried my a bit.
[youtube1]https://youtu.be/ZpmXh8ZKo1Y[/youtube1]
Since Christmas I was busy to learn more about the 3D CAM with 4th axis machining and it was necessary to find the right part for experiments.
I thought something with no straight line and no rectangle surface would be the right model for my experiment.
I have fond the below shown STL data file at Thingiverse.
A transformation from mesh to brep was necessary and a down scaling of the body.
At the end the part has got the right shape and size to be made from a round bar of d=45 mm and 100 mm length.
During the CAM preparation, the general concept has been changed minimum twice but it was a good leaning curve at the end.
If I honestly calculate all time I have spend with Fusion360 for the project and also the earlier made ball, it has been around 20 to 25 hours until I was happy with all the tool paths shown by the simulation. By the way there  are 22 tool paths with all finishing operations.
Unfortunately during the first rough cutting of the front, 4th or 5th layer, I have heard a strange noise and I could stop the program nearly in time.
Totally supersized I have found the cutter loosely in the collet. Never had this problem before, but a later discussion with the manufacture of my spindle has given an explanation. Perhaps I have used not the right pair of collet and nut. Anyway this is the reason for the injury of the Lady and anyway it is an experiment to learn more about this stuff.
[youtube1]https://youtu.be/yvQwRJZwyg4[/youtube1]
Also here are some crossing of tool paths where I am not happy with.
Unfortunately there has been another incident, after the finish of all rough machining, my mill has lost the signal of the end of the x axis.
It was necessary to remove the table to check the underneath switch.
The switch was fine, but the cable, deeper in the base of the mill was broken.
If i have found my correct X,Y,Z and A zero points again exactly, I do not know, so further trials should be made.
In the meantime I have been in a longer discussion with the German manufacture of the rotary table.
The backslash of the worm drive, 0,2 mm measured at radius 49 mm at the chuck, was another issue I was not happy with.
They have seen my videos of the measurement and they offered me to ship another brand new rotary table, so that I am able to compare it.
In the meantime I have got the second table and the measured backslash is less 0,06 mm now and the run out of the axial bearing is also acceptable now.
So I have said thank you very much and the not so nice one was collect by them next day.
Everything free of charge for me and may be it was a good idea here to buy at the known German company Proxxon and not anywhere else.
So I am really satisfied with their customer service.
« Last Edit: February 11, 2021, 02:08:58 PM by fumopuc »
Kind Regards
Achim

Offline Muzzer

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Re: CNC 4th axis up grade
« Reply #1 on: February 11, 2021, 06:54:52 PM »
Very interesting to hear about your experiences here, Achim!

When you say you used Fusion 360, did you have to pay for the "manufacturing extension" to access the simultaneous 4th axis toolpaths? I have the paid licence now but as far as I know, it only does indexing (wrapped) toolpaths and could not machine those curved(!) surfaces you managed so successfully. I can't bring myself to pay for the extension, although I believe you can at least obtain it for a short period at reduced cost.

Online vcutajar

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Re: CNC 4th axis up grade
« Reply #2 on: February 11, 2021, 09:24:30 PM »
Very interesting Achim.

Vince

Offline Bearcar1

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Re: CNC 4th axis up grade
« Reply #3 on: February 12, 2021, 12:02:20 AM »
 :popcorn: Achim, this is an interesting subject and I am watching to see your progress and further revelations you encounter... very interesting indeed. Please, keep us all posted... thank you and be safe.


BC1
Jim

Online fumopuc

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Re: CNC 4th axis up grade
« Reply #4 on: February 12, 2021, 06:32:07 AM »
Muzzer, Vince and Jim thank you very much for watching.


Hi Muzzer, the usage of the paid Fusion360 licence is mandatory for this type of machining but not the manufacturing extension.
The 4th axis was used for indexing only.
The torso is spitted in 4 surfaces, front,rear, left and right side.
Only two Fusion360 cutting strategies are choose for all operations.


  3D adaptiv cleaning for roughing down ( 6 mm flat end mill and 4 and 3 mm flat end mill partly for the very deep and narrow pockets, leaving 0,3 mm overstock)
  and
  3D parallel for final machining ( 3 mm ball cutter only for everything, in two steps, first taking 0,2 mm away of the 0,3 mm overstock and than the very last final machining with 0,1 mm infeed ) see the list below.

Also some pictures of the different process steps attaches.
Feel free to ask if you would like to get  more information or additional pictures of the simulation.
« Last Edit: February 12, 2021, 06:41:12 AM by fumopuc »
Kind Regards
Achim

Online fumopuc

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Re: CNC 4th axis up grade
« Reply #5 on: February 12, 2021, 06:34:49 AM »
...and some more pictures.
Kind Regards
Achim

Offline MJM460

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Re: CNC 4th axis up grade
« Reply #6 on: February 12, 2021, 11:06:03 AM »
Hi Achim, a wonderful example of what can be done with CNC plus that fourth axis.  Must be almost no limits to what you can do now.  Thanks for making those videos.

MJM460

The more I learn, the more I find that I still have to learn!

Online Vixen

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Re: CNC 4th axis up grade
« Reply #7 on: February 12, 2021, 04:34:00 PM »
Hello Achim,

Thats a very exciting first step into 4 axis machining and the subject matter is also very attractive.

May I ask so details about your process?

I understand how to create my own full 3D model using CAD or how to download a suitable STL file from Thingyverse.

I am not clear how you split the 3D model into the four surfaces: left, right, top and bottom. Is this something unique to Fusion360 or can it be done a different way?

I do not have Fusion360 but I do have other STL to Gcode generators. I have already made some nice single plane 3D sculptures and would like to try some more using my 4th axis. Machining four separate, 3 axis planes, looks like it can use simpler CAM software than simultaneous 4 axis

It's a slow process, once you feel confident you can leave the machine to do the work while you go inside to make some coffee.

Mike
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Sometimes, it can be a long and winding road

Online Jasonb

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Re: CNC 4th axis up grade
« Reply #8 on: February 12, 2021, 06:36:09 PM »
Fusion allows you to position the X, Y + Z axis where you want so for the simple indexing of the figure  you just set up four times each with Z at 90deg to the previous. Much the same way as you would setup to do two sides of a job by flipping Z 180deg.

Online Vixen

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Re: CNC 4th axis up grade
« Reply #9 on: February 12, 2021, 06:56:54 PM »
Obviously it can be done with Fusion360. I dont have Fusion360,

I was asking, is there a generic way chop up the STL file /model to create the four toolpaths for the four planes without using Fusion360

Mike
« Last Edit: February 12, 2021, 07:14:36 PM by Vixen »
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Online Jasonb

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Re: CNC 4th axis up grade
« Reply #10 on: February 12, 2021, 07:26:02 PM »
I don't think there is a need to chop it up, just alter what face if lined up with the cutter, the mill will remove all it can get to then the next index will get at some more and so on. It's no different to producing a 2D drawing from the part, each elevation gets machined one after the other.

Taking that figure you would have a job defining a straight split line, think back to the days of plastic model figures and the two halves of the injection mould followed the shape not a horizontal split line

Online Vixen

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Re: CNC 4th axis up grade
« Reply #11 on: February 12, 2021, 08:04:10 PM »
OK, that makes sense, just machine away all you can reach then rotate the A axis (4th axis) through 90 degrees and remove some more.

I think that means the software must be able to rotate the STL file/model about the same A axis or have the ability to redefine the X,Y and Z axes. Need to think how to do that.

Mike
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Online Jasonb

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Re: CNC 4th axis up grade
« Reply #12 on: February 12, 2021, 08:08:46 PM »
That's it.

In F360 you can locate the axis so for a job like this you could have it in the middle of a block so provided you rotated the block about that axis you would be OK.

Here is a quick simulation of a figure I picked off Grabcad. He would be machined laying down but you can see me showing how I have set the mill to have Z in 4 different positions and then I start the simulation which first cuts from the front, then side and so on each cut removing material left in the "shadow" of the previous cut.  I set the stock as a block but could also have been a cylinder It would not be hard to type in G-code between each face so the 4th axis turns the work or I would just do it manually.

Best watched at full screen. He was also a bit big, don't really want to spend 96hrs just roughing him out but shows the basic idea

<a href="https://www.youtube.com/watch?v=DpkRqxv3bqQ" target="_blank">http://www.youtube.com/watch?v=DpkRqxv3bqQ</a>


Online fumopuc

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Re: CNC 4th axis up grade
« Reply #13 on: February 12, 2021, 08:37:39 PM »
As Jason mentioned above, theoretical a manual set up is also possible.
i.e. a ER32 collet block in this case.
The tricky thing for me and my learning curve was to keep the cutter always in an extra defined x and y frame.
Left and right hand he should machine what he can get down to the split line, but not at the base an the neck, specially for front and rear.
For the sides x and y has been limited by the silhouette of the body and the advice to machine only remaining material from previous operations.
Kind Regards
Achim

Online Vixen

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Re: CNC 4th axis up grade
« Reply #14 on: February 12, 2021, 08:40:07 PM »
Jason,

Excellent simulation, it shows how Fusion360 does it rather well. Amusing how the man has three legs during the second face machining... Kelly from the Isle of Man??

But I don't have Fusion 360 so I'm trying to find a different way to achieve the same results.

I have ESTLcam which I use regularly for 2.5 D milling from DXF files. It can also produce tool paths from STL files but I have not played much with this section. It looks like I can re orientate the STL file axes in 90* steps in any direction. It also appears to have the ability (option) to automatically machine the front and back faces for a given orientation. Perhaps if I rotate the model once through 90*, I may be able to get it to do the other two faces.

I guess I know what I will be playing with for the next couple of days :thinking: :thinking: :thinking:

Mike

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Online Jasonb

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Re: CNC 4th axis up grade
« Reply #15 on: February 12, 2021, 08:44:17 PM »
Mike, I did that with the free version, though I seem to remember you said your computer may be a bit old as being a problem.

Online Vixen

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Re: CNC 4th axis up grade
« Reply #16 on: February 12, 2021, 08:56:56 PM »
Jason,
Yes, that's the problem, I do not have a computer modern enough to run the 'free' version of Fusion360  and I trying not to get involved with Windows 10. I prefer Linux.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline john mills

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Re: CNC 4th axis up grade
« Reply #17 on: February 13, 2021, 02:49:31 AM »
Hi
The 4th axis is good it means you can do all the sides in one setting the relation of each face right in relation to each face .if you have to re set using fixtures to locate each face errors creap in and holding the part can be difficult .years ago i was programming to make machine parts i had no cad cam  just paper and a calculator.
one machine had an indexer 12 divisions indexed with a M code it let me nearly compleat parts with one setting.
would have been very hard to hold after machining was started to do each face i just had to calculate the coordinatess from the centreline one job had added complications that the 2d drawing was bent part way along 7deg .if you can do each face one  at a time you can get the job done depending what  can do with your cad cam
system .have fun it can be interesting       John

Online Vixen

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Re: CNC 4th axis up grade
« Reply #18 on: February 13, 2021, 03:35:14 PM »
Jason, Achim,

Does Fusion360  machine all four sides from scratch, or is it clever enough to recognise and avoid those parts previously machined?

My Estlcam CAM software can only machine each of the 4 sides from scratch, no reduced machining.

Mike
« Last Edit: February 13, 2021, 08:39:34 PM by Vixen »
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Online Jasonb

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Re: CNC 4th axis up grade
« Reply #19 on: February 13, 2021, 07:43:26 PM »
I think you need the paid version for that and possibly even the extra "manufacturing" element.

Online fumopuc

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Re: CNC 4th axis up grade
« Reply #20 on: February 13, 2021, 08:25:55 PM »
Hi Mike,
picture 21 and 22 ist showing this reduced machining of the remaining material from previous operations.
Kind Regards
Achim

Online Vixen

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Re: CNC 4th axis up grade
« Reply #21 on: February 13, 2021, 08:38:41 PM »
Jason/ Achim,

I can see he reduced machining in the photos now you point it out.

Thanks

Mike
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Online fumopuc

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Re: CNC 4th axis up grade
« Reply #22 on: February 14, 2021, 07:01:40 AM »
Hi Mike,
I will try to show a bit more of the possibilities and my learning curve to reduce the surface for the cutter to work on.
The X Y frame can be selected either by the contour of the model or parts of it.
Additional it can be defined, that the cutter has to stay inside the frame, maximum on the contour or beside outside the selected contour.
I.e., one of the deep pockets in the rear. Picture 30.
The selected contour here was given by the model, more or less random.
It was selected to remove remaining material from the last operation now by a 4 mm flat end mill, all the previous roughing out was done by 6 mm flat end mill.
Visible in the simulated tool path picture 31 and the result of it at picture 32.
Another option to reduce the x y frame is by a sketch.
This I have used for another roughing out with the 3 mm ball cutter now. Picture 33.
Machined very carefully in 4 steps.
This 3 mm ball cutter was my one and only at this time. Picture 34, 35, 36, 37.
The surface in this pocket was now very close to the overall of 0,3 mm overstock, so ready prepared for the overall parallel final machining.
Due to the missing spare cutter, my target was to give as less as possible load on it.
« Last Edit: February 14, 2021, 07:31:25 AM by fumopuc »
Kind Regards
Achim

Online Vixen

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Re: CNC 4th axis up grade
« Reply #23 on: February 14, 2021, 02:29:47 PM »
Hello Achim,

Thank you for taking the time to show how you can reduce the size of the area to be worked on. My CAM software offers a similar XY frame to work within, but not the contour option.

It all becomes a big trade off between machine time and the fineness of the surface finish. With any curved 3D shape, narrow line spacing, whether linear or waterline contours will produce the finest finish but can consume vast amounts of time, measured in hours or even days of machine time. It becomes a judgement as to how much hand finishing with files, or scraper and sandpaper you are prepared to do.

Even a small diameter ball cutter can only go so far into a deep cleavage, It may be necessary to use a rounded tip engraving tool to achieve the last detail. However the machine time involved will greatly multiplied.

Mike
« Last Edit: February 14, 2021, 02:34:18 PM by Vixen »
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Online Jasonb

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Re: CNC 4th axis up grade
« Reply #24 on: February 14, 2021, 03:16:49 PM »
You will just need to add a higher speed spindle Mike so the small tools can be run and therefore fed faster to reduce overall time. ;)

As for reach add a few long neck tools to the shoping list

https://www.shop-apt.co.uk/2-flute-long-neck-carbide-ball-nose-end-mills-55hrc/page/2/

In fact the multi axis machines tend to use a more rugby ball shaped cutter where the side can be used more so the cutting speed is higher than the "dead" spot you get at the end of a ball nose tool.

Online Vixen

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Re: CNC 4th axis up grade
« Reply #25 on: February 14, 2021, 03:39:16 PM »
Jason,

If I bought one of those ' Long Neck Ball Nose Carbide Cutter 1.5mm Dia with a 16mm long Neck' for £12, I think I would be too afraid to give it ANY feed rate at all, no matter how high the spindle speed.  :facepalm:

Mike

PS, what speeds and feeds and depth of cut would be recommended for such a long thin 1.5mm dia cutter?
« Last Edit: February 14, 2021, 03:58:41 PM by Vixen »
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Offline kvom

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Re: CNC 4th axis up grade
« Reply #26 on: February 14, 2021, 04:24:03 PM »
This thread is quite interesting.  3D by flipping the work over in the vise was pretty well understood, but doing 90 degrees is excellent.  Even without a 4th axis holding the work in a square collet block would work.

Online Jasonb

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Re: CNC 4th axis up grade
« Reply #27 on: February 14, 2021, 04:38:23 PM »
Mike, APT are quite good and give some basic cutting parameters if you click the individual item.

https://www.shop-apt.co.uk/2-flute-long-neck-carbide-ball-nose-end-mills-55hrc/long-neck-ball-nose-carbide-cutter-1-5mm-dia-20mm-neck-length-50mm-long-55hrc.html

Yes easy to do with a collet block, spin indexer or a vertically mounted rotary table or if working on the end of a long bar just hang it out the side of your vice.

What would really impress is if the work were steadily rotating and the cutter ramping along it's length while going up and down in Z to follow the shape :)

Offline tvoght

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Re: CNC 4th axis up grade
« Reply #28 on: February 14, 2021, 04:55:01 PM »
The link below is my initial venture into 3d machining using 2 orthogonal passes. I used the squareness of the stock as a 90 degree reference, hanging the stock off the end of the vice as jasonb suggests will work for small parts. I created the model using an open-source tool oriented for more artsy 3d sculpting, but it worked quite well and would generate an STL file. Then I used Meshcam to generate g-code for the 2 passes. Meshcam is a reasonably priced Windows program which will run under Linux using the Wine emulator. That's how I use it.
I don't say it's quality work, I';m just sayin'
https://www.modelenginemaker.com/index.php/topic,5293.msg111257.html#msg111257
--Tim

Offline tvoght

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Re: CNC 4th axis up grade
« Reply #29 on: February 14, 2021, 05:09:59 PM »
And some slightly more on-topic work using the 4th axis:
https://www.modelenginemaker.com/index.php/topic,4974.msg95012.html#msg95012
--Tim

Offline Muzzer

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Re: CNC 4th axis up grade
« Reply #30 on: February 14, 2021, 09:39:33 PM »
What would really impress is if the work were steadily rotating and the cutter ramping along it's length while going up and down in Z to follow the shape :)

That's your true "simultaneous" multi axis toolpath. In Fusion it requires those darned "extensions".

 

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