FreeCAD: Post Processor for Duet-based CNC?

  • Hi all,

    I'm willing to give FreeCAD another try for a simple milling project. Can anyone recommend a particular post processor to use in order to generate output that the Duet will understand with the least amount of fiddling?
    ( has a list of default post-processors at the end).


  • I've been using FreeCad for a while now, since Fusion360 licensing seem to be sending warning signals for free users like me.

    I'm not using their CAM though, I'm exporting sketches as SVG files, and using EstlCAM to do tool paths. So, if someone has a process that results in fewer steps and getting good results, I'm all ears.

  • Update / intermediate results: The grbl post-processor appears to work fine for basic applications. I managed to crash the mill and break an endmill, but that was what's euphemistically called a "systems failure" in some industries - FreeCAD not setting a default feed rate and not warning about a feed rate being set, and Duet using the last used feed rate when a G1 without F is processed. Turns out the mill won't mill at jogging speeds... sigh

  • I also use the Path Workbench of FreeCAD together with a Duet CNC. Here I use the Marlin or the GRBL postprocessor, both work quite well. You might have to delete some G-commands from the file that the Duet does not know.

    I have also looked into writing a postprocessor for the Reprapfimeware myself. What are the special features of the Reprapfirmware compared to Marlin or GRBL?

    The postprocerssors of Freecad can be found here:
    Take the one from Marlin and adapt it for the Reprapfirmware. With the wonderful gcode reference from:

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