For a prefix the postprocessor should get the name _post.py. The postprocessor can be placed in your FreeCAD macro directory.

You can then have a look at the file and compare it to the output of existing postprocessors such as linux_cnc_post.py or grbl_post.py and try yourself to adapt them or you upload your to the Path forum to get some help. For a very first go you may provide only one level in the XY-plane. Please note the small blue arrow, it indicates the starting direction. The path in FreeCAD would look like this. no tool radius compensation must be applied. Make sure it is the tool itself moving along this path, i.e. Prepare it with any program suitable for your machine.Ī file for such paths starting at (0,0,0) and going towards Y would be helpful.

You may start with a very simple model showing how your machine reads straight lines and arcs. Preparation for writing your own postprocessor The postprocessor is a program which translates the internal codes into a complete file, that can be uploaded to your machine.

you might wish to include a custom header to identify or document the program for future reference.įurthermore there are other languages to control a mill, such as HPGL, DXF, or others.

you might wish to include comments for readability or suppress them to keep the program small.

it might be useful to perform a set of moves prior to calling for a tool change to make the action easier for the operator.

you might prefer your G-code output in either metric or imperial units.

it can used so called canned cycles for predefined subprocesses such as drilling.

it may require line numbers in a certain format.

arcs can be defined with a relative or an absolute center.the machine can have a special startup sequence.They may look almost like the internal codes, but there may be some differences: Many mills use G-codes as well to control the milling process. More sophisticated curves such as B-splines are already approximated by FreeCAD's Path Workbench. These movements are rather simple: They can be straight lines or they can be circular arcs. But the most important thing is the movements they describe. They can describe such things as: speed and feed rates, stopping the motor etc. 3 Preparation for writing your own postprocessorįreeCAD uses as internal representation for the generated paths, so called G-codes.2 What the postprocessor can do for you.

Freecad linuxcnc