Developments on my Home built 5C CNC Lathe - new spindle and progress on the ATC

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26 Sep 2021 05:47 #221610 by NoJo
Chris, may I suggest you look at the Gcode generated by modern CAM SW - you will find they all use G12.1/G13.1 or similar and therefore require that the machine control SW do the polar interpolation. So that's what I/we need Polar math for - it HAS to reside somewhere, either in the machine controller or in the CAM and , I would dare say, ALL 'modern' controllers embed those functions, so even CAM packages such as I mentioned use those Gcodes - they do not output incremental code..It's not as though one is 'programming' in polar coordinates - the CAM system must convert the part requirements into polar coordinated motion and generate X/C/Z moves, not G12.1, etc - at least that is what I need, but the even the $2k - $4k packages don't do it...

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26 Sep 2021 06:13 - 26 Sep 2021 06:20 #221612 by NoJo

Before throwing in the towel, you might approach some commercial CAM post processor vendors/authors about it.  It may be possible to have the post processor compute
 


Ralph - I have done exactly that - I had quite in-depth discussions with SPRUTECAM , MASTERCAM and the BobCAD/CAM folk. It took a lot of explaining to get them to understand the problem! The big issue was getting past the disbelief that a machine controller exists that cannot do Polar interpolation...When they understood,  MASTERCAM opted out ( even at $4500.00 a seat..) while SPRUTECAM and BobCAM came up with a proposal to add the capability - both in the region of $3500.00 for the effort, plus a cost TBD for the adaptation of a post processor. They were both serious in the approach to my needs - I am in Namibia, BobCAM is USA and SPRUTECAM in the UK ( for me in this part of the world) - Both phoned me a number of times for one-on-one discussions etc, but I eventually fended them off - I did not want to waste their time and then turn them away because of the cost!  This is all a Hobby for me - this lathe and the CAM, etc, will never earn money!

I have not tried F360 for lathe work - I used F360 to design and build my Polar 3D printer and it was just a mission - I dislike the complexity and the customer use model they have for F360 - if you don't use it for a few month it takes days to get back into it and re-learn all the convoluted command structure. I was also under the impression the C_axis post processing on F360 did not work?

I'm not sure about this-
I think polar interpolation was created to make it easier to hand-program complicated moves on fairly simple part features.  CAM doesn't (or shouldn't) need the machine to interpolate anything; just to go where it's told.
The motion required to cut a hex on the end of the shaft on a lathe demands interpolated angular moves with X tool position ( for a lathe with only 2 linear axis and one rotary..). The CAM has to convert this polar motion to incremental C axis angular moves coordinated with a relevant X axis linear move. So the CAM is doing the polar interpolation/conversion itself - or should be - I find none so far that do, except for what you say of F360.
Joe

3d printer pics - Extruder hotend is induction heated..




 
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Last edit: 26 Sep 2021 06:20 by NoJo.

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26 Sep 2021 07:47 #221613 by Aciera
That 3D printer seems to have an interesting kinematic, what controller do you use that with?

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26 Sep 2021 08:16 #221616 by tommylight

That 3D printer seems to have an interesting kinematic, what controller do you use that with?

+1
It looks "strange" for a 3D printer ! :)

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26 Sep 2021 11:21 #221625 by NoJo

That 3D printer seems to have an interesting kinematic, what controller do you use that with?

Well, again one of those things - I seem to do this stuff because I think I can - sometimes I succeed, sometimes I don't!
The controller is 'home made' - based on a Nucleo uController board - a sort of Arduino on steroids - 32bit cpu @ 80MHz. The software is also 'home made' - Reads  cartesian Gcode from Cura slicer - all done by my good Wife again - all the kinematics/reverse Kinematics and control. The hot end is an RF (10.1MHz) 80watt induction heated job - very fast, from 16deg C to 350decC in 5sec...
Why did I do it? As I said above, it was the challenge - I really have no need for a 3D printer - it has not been used since I proofed it!

We would be prepared to have a bash at creating Lathe polar kinematics for LCNC, but have no idea how to integrate it with LCNC, and how to add the G12.1/G13.1 Gcodes, etc... I think this is way beyond how this project started! "Everyone" told me LinuxCNC will do it - it can do anything..!

Anyway, don't wish to contaminate my lathe stuff too much with 3D printers, nor the LinuxCNC forum with non-LinuxCNC stuff, so just a few more pics then I'm done..
Joe

 

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26 Sep 2021 12:27 #221629 by Aciera

"Everyone" told me LinuxCNC will do it - it can do anything..!

While I wouldn't say that it can do 'anything', it has certainly been shown to be a very useful software to get all kinds of things working. Seems to me that if you can get that 3D printer with it's custom kinematics working on your own board then you and your wife should be able to get your c-axis working using linuxcnc. Creating a custom kinematic component has certainly become easy enough. Even somebody like me, who has only rudimentary knowledge of C, can throw something usable together. 
If you have a look at the post I referred you to earlier you can also find a link to the 'userkins' documentation.
 
The following user(s) said Thank You: tommylight

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26 Sep 2021 13:01 - 26 Sep 2021 13:02 #221630 by NoJo
The creation of the kinematics is not the issue for us really - its how to integrate it etc..We know too little yet of the hooks and links to tie in but we can learn...
Just to note - The C axis IS working, its polar interp. which is lacking...We are digging through your post now..
Thanks
Joe
Last edit: 26 Sep 2021 13:02 by NoJo.

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26 Sep 2021 13:25 #221631 by chris@cnc
G112 or G12.1 on Fanuc controls is option.  Long time ago but its possible to write your own macro.  You will found some example how to calculate.  I can't do this anymore.

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27 Sep 2021 00:17 #221668 by spumco

 

So the CAM is doing the polar interpolation/conversion itself - or should be - I find none so far that do, except for what you say of F360.
Joe

 


The CAM software isn't doing polar interpolation.  It's the post processor that outputs G-code in a dialect that your machine control can use.  What I was suggesting wasn't getting in touch with the actual CAM OEM's, but rather a 3rd-party post processor company.  There are plenty of people out there who write or edit/tweak post processors for customers.

Could be as simple as "I want the machine to move to a certain park position after every M30".  Or as complicated as "I want a post processor that integrates a robot unloader with my 12 axis swiss lathe."

It's the post that is special.  If the CAM software can output 3-axis moves, that's all you need.  The CAM will output X/Y/Z moves, and the post processor will convert the Y-axis to coordinated X/C moves.

F360 isn't special - and I'll agree it has warts, especially for the lathe side.  But I get the impression that writing/editing the post processors for it are not as complicated as for some other CAM software.

I would just do an internet search for "Post Processor Editor Service" and start sending out emails to those companies (not the CAM vendors).  Simply ask them if they can create a post that will convert XYZ moves to XZC moves without polar interpolation.

My XZC F360 post cost me $900US, primarily because the Emco version of Fanuc is poorly documented and there were many, many iterations required.  I would expect what you're looking for would be in the neighborhood of $700-$2500, depending on the effort (i.e. post from scratch, vs. editing an already-proven post just for this single feature)

If it's enough money that you are reluctant, we could try to do a group-buy and have a professional post processor available for LCNC live-tool lathes.  I'd be willing to throw in a bit if I knew I had that available at the end of a retrofit.

-Ralph

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27 Sep 2021 05:44 #221687 by NoJo

The CAM software isn't doing polar interpolation.  It's the post processor that outputs G-code in a dialect that your machine control can use. 

Perhaps I did not express myself very well there...What I mean is that I would need the CAM SW to do the interpolation and out put a(large..) file of discrete moves in Xmm/Cangle - What you suggest is a post-post processing tool to do just that from the standard CAM's polar notation. Obviously there are a number of options and ways of approaching this, but certainly for me this is purely a hobby- I am a retired Aeronautical Engineer, not machine shop enterprise in my life! -This machine and the CAM will never earn money, let alone pay for it's costs! So I would certainly be a little circumspect spending $2000.00 on a post-post processor, even $700.00 will buy me a heap of tooling to play with..
I am going to try develop the kinematics for it and see how that goes to start..
In the meantime, the lathe looks pretty on the mantelpiece! 

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