Custom gcode for cut start/end?

Is it possible in lightburn to add custom bits of gcode at the start and end of a cut? I’m planning to use it for a plasma cutter and need to do a touch off on the material before the torch fires, then lift to a pierce height, fire the torch, pause for some amount of time based on material and thickness, drop to the cut height, activate the height controller and start the cut.

This looks something like

M100
M28.2 Z
G92 Z0
M101
G0 Z3
M3
G4 PX.XX (pierce time, needs to change based on material)
G1 Z0.8
M10

Can lightburn do anything like this? I remembe asking a few years ago and I think the response was it was not implemented yet.

I don’t have a GRBL device but I do know for those devices, there’s the ability to create macros in tge control panel.

Speaking from cnc experience, I’d create a macro with whatever you need to set the plasma cutter as described above, then call that macro from within the GCode.

Yes, you can add custom Start and End GCode by going to ‘Edit’ > ‘Device Settings’ > ‘GCode’

@JTR That’s a job instance custom code block, rather what is needed is a per cut instance custom code block, for example a custom code block in the layer definition.

@Trak , for the reason you mention and for other nice to have toolpath features, I use LB for 2D design, export SVG, then import into SheetCAM for the toolpath. The cycle time in this work flow is seconds.

Originally I had written my own plasma post processor for LB grbl gcode for the reason you mention, but due to other per cut/shape UI challenges with LB such as: constantly editing start point and direction, not to mention frequent lead-in angle adjustments, and not getting a visual of the kerf width, just to name the biggies, I decided to go with SheetCAM instead. SheetCAM improved my plasma process success 10x over the hammer head method I was using.

Last summer, in response to LB interest in a future plasma process toolpath and toolpath editing UI, I submitted to them a list of plasma process ‘nice to have’ functions and features.

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