Problem with Z origin - set Z0

[Pieri70 (pietro rossin)]

Hello
I own a CNC grbl 1.1f with a neje diode laser on it.
Endstop are back-right and Z home is at Z max
I followed the documentation on how to set a workspace offset for negative coordinate machine like mine

Negative Coordinate Machine Setup

Negative Coordinate Machines If your machine uses negative coordinate space, we need to offset the origin. LightBurn wants positive workspace numbers, like this: [image] This image shows the origin at the front-left, with positive X values moving to the right, and positive Y values heading to the rear of the machine. A negative workspace system looks like this: [image] In this image, the origin is at the rear-right of the machine. The X and Y directions are the same as before, but now, to …

My machine is 540mm on X and 910mm on Y.
Z zeroes @+35mm machine workspace
In my case I set
G10 L2 P1 X-540 Y-910
So if I make a home machine and then tell lightburn to go X0 Y0 all is fine.
But Z is zero at homing position (+35mm)
I then lower Z to focus level and If I tell lightburn to cut in absolute positions the cut start but Z returns to zero (+35 in machine coordinates).
Is there some way to set Z zero workspace coordinate at focus height?
So I can tell lightburn to go X0/Y0 then lower Z at focus and set Z0?
This height changes in relation to piece thickness…
Something similar to what I do with milling operations…
Thanks
Pietro

[Pieri70 (pietro rossin)]

I found the solution. I must set relative Z movements in setup
Thanks