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Maybe later a parameter can be added of how often or what is the minimum distance the torch has to travel before it re-zeroes the Z, trying to avoid too many zeroings.

My question is what should i read in order to customize the post processor.

My exact need is to replace the G0 Z direction rapid moves with the Z zeroing probing code.

After each cut most likely the Torch Height Controller which interferes the Z signals and takes control of the Z movement, will have the Z in an unknown location and definitely not aligned for the next path.

So I would like to insert something like G38.3 Z-100 F10 G0 L20 P1 Z-1.5 G0 Z0 M3.

So the zero is 1.5mm above the metal I have a feeling I have to study python A 2nd need is to turn the plasma off (M5) and on (M3) between rapid movements.

In fact, the wiki page about customizing post processors is a bit thin.

But Ill be happy to help Probably the best thing is to look at the existing post processor code.

The posts are mostly self-contained scripts and not too complicated.

Looking at the GRBL post, the code down to line 140 is setup, defining some globals, and parsing the arguments.

Nothing too interesting unless you want to add new arguments.

Export() handles the big picture and assembles one big-ass gcode string which is the final output.

Export() decides whether or not to insert tool change code, spits out unit strings for the machine, headers, comments, etc.

Any changes in how the machine behaves between operations is probably going to be here.

Starting around 184, it iterates through all the objects in the job, outputs comments, and then passes the individual object (tool change, operation, etc) to Parse().

Any changes to how individual commands are output or processed is going to be in Parse.

Its iterating each command (c) in the path object and deciding what to do.

Youll need to add logic that understands whats happening in the gcode and does the right thing.

For comparison, look at the parse() routine in the linuxcnc post around 297.

If similar logic existed in grbl, the else clause at 304 is where Id insert logic to turn off the torch, for example.

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Feel free to ask lots of questions or catch me on IRC at freecad or in the gitterpath room.

A big parenthesis here is that after some thinking I would like be able to add in the regular PATH workbench: Something that converts the whole Workbench to 2D.

The code is already there, actually is simpler imho With 2D somewhere we could add some constants like a)Initial Height Probing Commands b) Safe height c) Plasma cut height So before it even reach the post processor the PATH will generate useful code.

It can use the b) to move in the starting point, run the a) function in the g-code, move into c) height, and run the regular command (like the Face Profile) only that now it adds the M3M5 at any raisedepression of the tool.