Setting working Z height.

Nightowl

I've run a flattening toolpath to, erm, flatten one surface of a piece of stock, so I can turn it over and use that as the known flat surface for the rest of the CNC project.

The toolpath is simple enough and, when the job is complete, the milling motor is moved to 5mm above the start point (X0, Y0, Z5)

If I want to run the toolpath again, I move the move the Z axis to Z0, then down 0.1mm, reset the Work Home and restart the job.

Obviously, the work X, Y and Z dimensions haven't changed, but is the a command that can set Z0 (or any of the axes) without going through that kerfuffle? Perhaps there's something I could enter in the command line box, e.g:

New Z height = Old Z height - 0.1?

...for example? Or perhaps a macro?

I suppose it's a bit like G92, but for working coordinates.

Thanks

Phaedrux

G92 with a conditional Z height statement perhaps?

Nightowl

@Phaedrux
I’m not sure what a conditional statement would entail, but if the working Z height is currently 70 (Z70), for example, could I use M92 Z75 in the command line would that change the working Z height to 75?

Thanks

Phaedrux

Could you use baby stepping? Or does the Z position actually need to change for this?

https://docs.duet3d.com/en/User_manual/Reference/Gcode_meta_commands

To find the current z position as a variable check the object model browser.

Nightowl

@Phaedrux
I think what I'm looking for is a short macro (ZAdjustDown.g) which I could run from the command line, that will adjust the existing Z work zero by -0.1mm.

When the surfacing process is complete, the tool returns to Work coordinates X0, Y0, Z+5, but I would like the macro to change the actual Z starting point (without moving the spindle down) by -0.1mm, so that when I repeat the project, the spindle is moved down to the new start point and starts cutting from there.

I intend to assign the macro to a button on my jog controller, so I won't be necessary to enter it in the command line.

Thanks