Post Processing Fails to Post (Machine Argument Not Defined)

[SaazyTheGoat]

• OS: Linux, EndeavourOS
• Desktop Environment: KDE
• FreeCAD Version: AppImage, v1.1.0dev, 2025/05/23
• Architecture: x86_64

Error during post. Argument Required: --machine. The other post processing files work fine. Generic Marlin exports correctly and generates a gcode file with commands.

2freecad: error: the following arguments are required: --machine
22:22:43  Running the Python command 'CAM_Post' failed:
Traceback (most recent call last):
  File "/tmp/.mount_FreeCAaDlNCK/usr/Mod/CAM/Path/Post/Command.py", line 216, in Activated
    post_data = postprocessor.export()
                ^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 836, in export
    (flag, args) = self.snapmaker_process_arguments()
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 482, in snapmaker_process_arguments
    (flag, args) = Path.Post.UtilsArguments.process_shared_arguments(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/Mod/CAM/Path/Post/UtilsArguments.py", line 688, in process_shared_arguments
    args = parser.parse_args(shlex.split(argstring))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/lib/python3.11/argparse.py", line 1874, in parse_args
    args, argv = self.parse_known_args(args, namespace)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/lib/python3.11/argparse.py", line 1907, in parse_known_args
    namespace, args = self._parse_known_args(args, namespace)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAaDlNCK/usr/lib/python3.11/argparse.py", line 2156, in _parse_known_args
    self.error(_('the following arguments are required: %s') %
  File "/tmp/.mount_FreeCAaDlNCK/usr/lib/python3.11/argparse.py", line 2640, in error
    self.exit(2, _('%(prog)s: error: %(message)s\n') % args)
  File "/tmp/.mount_FreeCAaDlNCK/usr/lib/python3.11/argparse.py", line 2627, in exit
    _sys.exit(status)

[clsergent]

Hi,

Did you try to add the --machine argument to find out if the error is solely related to the argument (which is not mandatory even if I strongly advise to add it). Here are the possible choices (from the help message):

--machine {original, original_z_extension,a150,A250,A250T,A350,A350T, artisan}

I did not encounter this error myself. It could be related to the posprocessing API which is not fully stabilised.
Could you please provide the revision number (should be around 40 000)?

[SaazyTheGoat]

So, using the --machine argument does make the error go away. It's replaced with a new error to utilize the --toolhead argument. Once both of those are added, I get a PostUtils is not defined error.

2Spindle speed will be controlled using using percentages.
18:12:38  Running the Python command 'CAM_Post' failed:
Traceback (most recent call last):
  File "/tmp/.mount_FreeCAMDFApE/usr/Mod/CAM/Path/Post/Command.py", line 216, in Activated
    post_data = postprocessor.export()
                ^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAMDFApE/usr/Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 838, in export
    return self.snapmaker_process_postables(filename)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAMDFApE/usr/Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 611, in snapmaker_process_postables
    gcode = self.export_common(objects, filename.format(name=name))
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_FreeCAMDFApE/usr/Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 814, in export_common
    dia = PostUtils.GCodeEditorDialog()
          ^^^^^^^^^

name 'PostUtils' is not defined

Revision Number: 41837 (GIT)

I can try building the freecad-git package from source tonight over the AppImage.
Edit: freecad-git build has the same issues as the AppImage for me.

[clsergent]

Ok this definitely an API change, your revision number is way ahead of mine.
I will dig further and make the appropriate changes.

In the meantime, if you need the post processor, you can try the old one which is not built on top of the post processing API, or use a non beta version of FreeCAD.

[SaazyTheGoat]

Makes sense. Wish I could be of more assistance helping with the API change but alas my programming is rusty.

I did try your older version on FreeCAD 1.0.1 and it works just fine for those fighting similar struggles.

One thing I noticed, after setting the origin and hitting run, the spindle is moved to Z-Maximum and then pauses waiting for the user to hit resume. Afterwards it moves to the first position and starts cutting. If that's being added to the gcode by the post processor, I'd personally eliminate the pause. There's not much need (at least from my perspective) to have it pause moments after I told it to run. I don't mind the spindle moving well above safe travel heights to get to the first position but I don't need to approve it to run effectively twice.

[clsergent]

Hi,
I know it has been a long time since my last comment, sorry for the delay (work/family/vacation issues...)
Anyway, after reviewing the code of the postprocessor, it turns out that someone modified the postprocessor after me, eventually aliasing Path.Post.Utils as PostUtils. Anyway, it should now work, unless you tried to call the function without the FreeCAD GUI.

As for the initial pause, it is caused by the tool change behaviour, which is applied each time a new tool is detected (including the first one). There is actually no elegant way to remove the first tool change only. You can however alter the default tool change behaviour with args like --no-tool_change or --tool_change="", but it's relevant only if you only use one toolhead.

I hope I addressed your questions. Stay tuned for new updates which should come soon!

[rabbitboy84]

Hello,
I'm running into a similar issue. Has there been a fix for this? I'm tired of using Luban and waiting 6 years to cut a simple recess :)

[clsergent]

Hi,
I've not used my postprocessor for a while, and my last PR to FreeCAD was never merged...
Anyway, could you provide me with your OS/FreeCAD version, and I'll try my best to make it work.

[rabbitboy84]

Sorry for the delay; I was at work. I have an A350, using Windows, and FreeCAD 1.1.0

[ipeco85]

Hi, I just wanted to use FreeCAD for CNC machining on my Snapmaker. I own both an Artisan and an A250 machine. I use FreeCAD for years, but i'm new to the CAM module, now really disappointed with the limited CNC features of the Luban software. I successfully went through some CAM learning videos, but failed with the snapmaker output - see added snapshot. I use FreeCAD 1.1.0 from 26/03/25 with standard installation on a WIN 11 desktop. Please advise how to overcome the problems. Installing "machines" as add-on didn't change any issues
Many thanks in advance.
Peter

Type Notifier Message

• Running the Python conmmand "CAM_Post' failed:
  Traceback (most recent call last):
  File "C:\Program Files\FreeCAD 1.1\Mod\CAM\Path\Post\Command.py", line 217, in Activated
  post_data = postprocessor.export)

File "C:\Program Files\FreeCAD 1.1\Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 837, in export
(flag, args) = self.snapmaker_process_arguments(}

File "C:\Program Files\FreeCAD 1.1\Mod/CAM/Path/Post/scripts/snapmaker_post.py", line 483, in
snapmaker_process_arguments
(flag, args) = Path.Post.UtilsArguments.process_shared_arguments(

File "C:\Program Files\FreeCAD 1.1\Mod\CAMPath\Post\UtilsArguments.py", line 773, in process_shared_arguments
args = parser.parse_args(shlex.split(argstring))

File "C:\Program Files\FreeCAD 1.1\bin\Lib\argparse.py", line 1874, in parse_args
args, argy = self.parse_known_args(args, namespace)

File "C:\Program Files\FreeCAD 1.1\bin\Lib\argparse.py", line 1907, in parse_known_args
namespace, args = self._parse_known_argslargs, namespace)

File "C:\Program Files\FreeCAD 1.1\bin\Lib\argparse.py", line 2156, in parse_known_args
self.error(‘the following arguments are required: %s‘) %
File "C:\Program Files\FreeCAD 1.1\bin\Lib\argparse.py", line 2640. in error
self.exit(2, _(%(prog)s: error:%(message}s\n') % args)
File "C:\Program Files\FreeCAD 1.1\bin\Lib\argparse.py", line 2627, in exit
_sys.exit(status)
2

• freecad.exe: error the following arguments are required: --machine

[clsergent]

Hi,

• Very naïve question, did you set --machine=A250 (respectively Artisan)? Check https://github.com/clsergent/Snapmaker2Postprocessor/wiki/FAQ#how-to-add-a-post-processor-argument for how to set this argument.
  I definitely need to find some time to check the new postprocessor API...

[ipeco85]

Hello, thanks a lot for your quick response! Indeed I didn't know that any arguments have to be added. Using the 'machine' and "toolhead" arguments the output seems to come without errors. All other arguments have to be evaluated, not every one sounds familiar to me ..
Again many thanks and have a nice evening!