FreeCAD_cam - tool change set up problems

J_K · February 14, 2025, 10:04am

Hi
does anyone use freecad cam to generate gcode?
I have a problem with setting the tool change, it seems that $HZ is not recognized in the program.
I use grbl PP in Freecad

When I adding

I get an error

and after removing from snippet “Z home” line then the program is happy

any suggestion?

jeyeager · February 14, 2025, 12:42pm

I haven’t tried FreeCAD CAM but $HZ (and anything starting with $) is FluidNC specific and not a GRBL command. It seems that it must be trying to parse it.

RockinRiley · February 14, 2025, 12:56pm

that looks like it would be possibly a macro, is that in the documentation? I had not yet seen that!

So that is definitely in my searches for $HZ and I believe it to be only for fluidnc, but as I stated, I had not yet seen that.

I will have to try that when ever My frozen tundra warms up and I can stand to be in my garage!

jeyeager · February 14, 2025, 1:02pm

That’s the normal FluidNC tool change code from the V1 documentation. It just seems that FreeCAD doesn’t like the non-GRBL commands.

J_K · February 15, 2025, 7:04pm

Worse, because if I replacing $HZ for #define HOMING CYCLE 0 (1<<Z AXIS) (grbl homing) it’s doesn’t working either

jeyeager · February 15, 2025, 7:11pm

Right. I believe it requires some kind of code change to work with FluidNC. I’m not sure if that’s to FreeCAD or the GRBL post processor.

github.com/FreeCAD/FreeCAD

src/Mod/CAM/Path/Post/scripts/grbl_post.py

main

# -*- coding: utf-8 -*-
# ***************************************************************************
# *   Copyright (c) 2014 sliptonic <shopinthewoods@gmail.com>               *
# *   Copyright (c) 2018, 2019 Gauthier Briere                              *
# *   Copyright (c) 2019, 2020 Schildkroet                                  *
# *                                                                         *
# *   This file is part of the FreeCAD CAx development system.              *
# *                                                                         *
# *   This program is free software; you can redistribute it and/or modify  *
# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
# *   as published by the Free Software Foundation; either version 2 of     *
# *   the License, or (at your option) any later version.                   *
# *   for detail see the LICENCE text file.                                 *
# *                                                                         *
# *   FreeCAD is distributed in the hope that it will be useful,            *
# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
# *   GNU Lesser General Public License for more details.                   *
# *                                                                         *
# *   You should have received a copy of the GNU Library General Public     *

This file has been truncated. show original

J_K · February 15, 2025, 9:04pm

You are probably right, i think something should be done one FreeCAD side because grbl should support the $H command.

jeyeager · February 15, 2025, 10:14pm

Oh boy. I tried to take a look at how to use FreeCAD CAM and there’s quite a learning curve. I doubt I’ll be using this over Estlcam anytime soon.

J_K · February 15, 2025, 10:30pm

I’m from F360 (and recently onesape) and this two are similar. Estlcam is harsh for me but mor important it not support stl files so i have to use FreeCAD

J_K · February 15, 2025, 10:33pm

do you think manually placing snipping (tool change) to gcode (generated from FCAD) will work?

Tokoloshe · February 15, 2025, 10:34pm

Estlcam does support stls.

J_K · February 15, 2025, 10:40pm

So, I think i have some learning to do

Shame it’s not available on Linux.

J_K · February 15, 2025, 10:49pm

STEP too?

Tokoloshe · February 15, 2025, 10:52pm

Don’t think so.

J_K · February 27, 2025, 2:28pm

UPDATE
Kind of working but not working.
STEP support is really bad, it does everything for you but not good at all. You have 0 capabilities to change

WORK AROUND
main goal - tool change
manually put the code (modified code from the website) in NC files

(Begin operation: tool change)
(Path: tool change)
(tool change)
(Begin Custom)
(1turn off pin 27)
$HZ (home Z)
G0 X10.000 Y10.000
M0
(1turn on pin27)
(End Custom)
(Finish operation: tool change)

J_K · March 10, 2025, 2:20pm

EDIT
Code need to be like this to be able to back to the workpiece

$HZ (home Z)
G0 X0.000 Y0.000 (powrot do poczastku wspolrzednych)
M0 (zatrzymanie maszyny)
G38.2 G91 Z-110 F200 P0.50 (Probe set thickness)
G90
G00 Z35.0000 F500 (Clearance)
M0 (MSG remove probe)