Plasma workflow

[f3nix]

Hi!
I'm in the process of building a DIY 1250x1250 plasma cutter (ETA several months). I'm planning to use LinuxCNC on it.

Is Path workbench suitable for Plasma cutting already? If yes. Are there any examples of the workflow?

Please bare with me. I'm very new to all this

Thanks.

Cheers,
Mateusz

[herbk]

Hi Mateusz,
in my mind it should work. Of course you need to set some parameters "tricky" because you don't need a stepdown but a well placed "first layer", which a mill allready needs inside the workpeace.

Use the Path "contour pathes" and create a tool with the diameter of your beam. Only the commands for switching on and off the beeam you need to insert by hand...

[chrisb]

I'm in the process of building a DIY 1250x1250 plasma cutter (ETA several months).

I would like to know more about this interesting project.

Only the commands for switching on and off the beeam you need to insert by hand...

And even that could be done in a dedicated postprocessor, something like switching off on first rapid speed and on on first normal speed command in a sequence.

[f3nix]

Hi Mateusz,
in my mind it should work. Of course you need to set some parameters "tricky" because you don't need a stepdown but a well placed "first layer", which a mill allready needs inside the workpeace.

Use the Path "contour pathes" and create a tool with the diameter of your beam. Only the commands for switching on and off the beeam you need to insert by hand...

Is Path able to generate toolpaths like here? For example: corner looping, lead in for circles...

I would like to know more about this interesting project.

It is heavily based on instructions and ideas from internet.
1. Parts were drawn, bent and assembled with 0.16.
2. Unbending (using slightly modified SheetMetal WB to correct the k-factor), export to DXF and bending drawings made using 0.17.

Parts were laser cut and cnc bent. I have MIG welded some of the parts and then after checking that everything fits correctly I sent it for powder coating.

Two things I did not foresee:
1. The powder coater said that the thickness of the paint layer will be no more than 50microns. Finally it worked out to be 0,5mm to 1,5mm :/ Now I have to shim some stuff to get proper geometry.
2. Chinese technical drawings do not correspond to real elements. I had to redo some parts for the fasteners to be in correct places.

So I'm learning as I go

freecad-shot.jpg (243.93 KiB) Viewed 5629 times

DSC_1760.jpg (495.79 KiB) Viewed 5629 times

DSC_1761.jpg (485.46 KiB) Viewed 5629 times

Cheers,
Mateusz

[chrisb]

Is Path able to generate toolpaths like here? For example: corner looping, lead in for circles...

Thanks for sharing the images.
FreeCAD can currently not do these fancy corner transitions but the dragknife dressup seems to follow a similar approach so that I would think it not to be a big deal. I don't know the lead in for circles: Is that something like ramping - which is implemented in FreeCAD?

Currently FreeCAD optimizes tha paths to have short rapid moves between them. I'm not sure what effort it would take to distinguish between inside and outside like the linked software does.

[polemidis]

I designed my plasma cnc and build it a few days ago. Unfortunately so far the Freecad CAM is not good enough for plasma yet. The lead in/out is kind of important as the torch on/of. I use the PATH workbench heavily on my CNC Router, but for plasma these features are important. About the torch on/off maybe a post processor can replace the Z down movement with just the auto leveling routine+M3, I do not see that too difficult. Or maybe a option that uses just the 2D

I uploaded the project on https://github.com/goscommons/CNC-Plasma-Table.git, we are working to make it nice. On the "01 Design Issues" folder I have some pictures of the actual machine. One of my first videos is https://www.facebook.com/polemidis/vide ... 668246740/

Hopefully the Path will be suitable for plasma soon. Until then my only option is the SheetCam.

[dbecad]

Is Path workbench suitable for Plasma cutting already? If yes. Are there any examples of the workflow?

This plasma cutter project is pretty amazing :0 keep the pictures coming!
Regarding the workflow, I've looked on the forum for a similar answer and did not find a good way to do it (please So correct me if i'm wrong).
I'm working on an involved first project trying to design a wooden mechanical clock that would be cut using laser cutter so mostly 1D cuts like plasma. The cutter software I have access to is taking DXF so i need to create profiles for all the pieces but the dxf export is not really useful as it does not preserve the part-locations and all the pieces end up on top of each other. So I'll be updating something like the script to generate a cutting plate in one shot with minimal intervention. After that you should be able to find a dxf/svg -> Gcodes cam package.

Cheers

[sliptonic]

Unfortunately so far the Freecad CAM is not good enough for plasma yet.

Hopefully the Path will be suitable for plasma soon. Until then my only option is the SheetCam.

I'm going to push back on your post. You're not giving any indication of how the lead in/out should work or how torch control is done in other applications. Just saying the current is 'not good enough' isn't really helpful. I've never run a plasma table so it's going to be hard for me to write a feature without doing a bunch of research and duplicating expertise that you already have.

Some possible things you could do, in no particular order:

• Draw some pictures of what the movement should look like
• Link to some relevant websites
• Describe in detail how the feature should work and the options.
• Try your hand at writing a macro that produces the right movements.
• Link to some youtube videos
• Enter a mantis feature request
• When the feature works, write the wiki page about using it
• Make a video showing it off

My gut tells me what's needed is some customization to the post-processor as you noted for torch control and a new dressup for plasma lead in/out.

BTW, That's a nice looking plasma table project. Very cool.

[Konstantin]

I have some experience in using FreeCAD for plasma. If you remember, here we discussed a little bit.

My machine does not need to set parameters in program, only speed, so it was easy to adapt postprocessor for my needs, I needed only to cut open contours. But even then I had some inconvenience:

• I can't point a starting point, FreeCAD starts where he wants.
  
  But for more serious work it is a must additionally to have a:
• Good working DXF importing format (and it's a real problem not only in FreeCAD, It's a pain in opensource programs) But It's not Path workbench related
• Leadin/Leadout - It must lead in from outside to the starting point, and leadout outside. For now that I tried it - it just doesnt work right. Even for milling. I wanted to start a new thread about this problem, by the way.
• Cutting regimes. Man I hardly imagine it would be done without serious material management, torch management, corner management... And add to this how different controllers can be, No, I don't believe it can be done. No silver bullet in this area.
• Nesting. Someone said in architecture workbench they started something, but I don't know, is there any progress in this direction?

Just my 35 and half cents.

[polemidis]

I'm going to push back on your post. You're not giving any indication of how the lead in/out should work or how torch control is done in other applications. Just saying the current is 'not good enough' isn't really helpful. I've never run a plasma table so it's going to be hard for me to write a feature without doing a bunch of research and duplicating expertise that you already have.

Some possible things you could do, in no particular order:

• Draw some pictures of what the movement should look like
• Link to some relevant websites
• Describe in detail how the feature should work and the options.
• Try your hand at writing a macro that produces the right movements.
• Link to some youtube videos
• Enter a mantis feature request
• When the feature works, write the wiki page about using it
• Make a video showing it off

My gut tells me what's needed is some customization to the post-processor as you noted for torch control and a new dressup for plasma lead in/out.

BTW, That's a nice looking plasma table project. Very cool.

You are right. I will do my part trying to contribute to this project. What I really want to plasma cut is the https://github.com/goscommons/Grapples (you can open the Master CAD under the 01hardware folder). I will start with the simplest part and write exactly was is going wrong. Maybe I was too scared and didn;t dig enough when I posted, my apologies.

Btw I saw your videos, and are GREAT!!
One quick question though hopefully will not divert the discussion out of the subject. What is your approach when an object is designed on a different plane? ZY for example. Do you rotate the "Base Body" and use the orientation and aligment under the Setup Tab of the Job? or is there any other way?