Constant - Material Thickness Z movement: how to accomplish

[gsrunion (Steve Runion)]

Question:
How can I get LightBurn to generate G0 Z-(Constant - Material) thickness movements at the start of gcode? I have 2 solutions that are workable but not ideal. This is pretty workable but doesn’t cover cases where use just decide to put a thickness on a layer instead of assigning a material to a layer.

1. in my material library tell LightBurn that the thickness is constant - thickness and turn on the z travel and the negative z settings in the machine settings.

2. manually add a G0 Z-constant to the machine start gcode and set the material setting to what it is. From the looking at the gcode that would put some rapid G0 moves very close to the machine bed and potentially crashing into material…

`; LightBurn 1.3.01
; GRBL device profile, absolute coords
; Bounds: X48 Y41 to X98 Y97

;USER START SCRIPT
G0 Z-21
;USER START SCRIPT

G00 G17 G40 G21 G54
G90
M4
; Cut @ 5 mm/sec, 100% power
M8
G0 X48Y41
G0 Z3`

Background:
My laser manufacturer (XTool) is finally opening up LightBurn support for my machine (LaserBox Co2) by allowing their proprietary software to be used as a gcode sender. In this flow you do your design in LightBurn, save the gcode to file, and then use their software to push to the machine. The manufacturers solution to adjusting for material height has one manually adding a G0 Z-? command to the start gcode under settings. How could I leverage LightBurn to avoid that.

[ednisley]

@gsrunion

allowing their proprietary software to be used as a gcode sender

Stipulated: I don’t own an xTool and have nothing to do with them.

That they think it makes sense to require manual intervention on every file just to get the focus right suggests you are about to enter a world of hurt, where things that Just Work™ with a GRBL controller become a never-ending series of “How do I do X?” problems with no good solutions.

IMO, you’d be better off to rip out their proprietary controller, drop in anything else that runs vanilla GRBL on hardware with known-good LightBurn support, and move on. It will require an up-front hardware investment and some amount of tinkering that will pay back forever by eliminating all their hacky work-arounds.

[gsrunion (Steve Runion)]

I don’t think anybody ever accused them of doing anything right.