You will need to alter it to G1, G2, or G3 if you want to manually turn on your laser. Please remember that G0 is the default motion mode upon power up and reset. When changed to a G1 G2 G3 modal state, Grbl will immediately enable the laser based on the current running state. In other words, a G0 rapid motion mode or G38.x probe cycle will never turn on and always disable the laser, but will still update the running modal state. The laser will only turn on when Grbl is in a G1, G2, or G3 motion mode. The LightBurn gcode turns the laser ON as soon as M4 is issued (or our GRBL fork doesn't respect the G0 gcode command per the official GRBL v1.1e release). The Inkscape-generated gcode works perfectly fine.

LightBurn-generated gcode (controlled by LightBurn): Inkscape-generated gcode (controlled by CNCjs): In their implementation, M4 is used to enable the laser and then G0 is used to actually turn the laser OFF and G1 is used to turn the laser ON during cutting. Apparently LightBurn is supporting >= GRBL 1.1e (which it looks like our boards firmware uses based on the github repo - v1.1e). the laser did not turn off during travel moves). What's the trick to get the LightBurn software working properly with our boards? I tried it out tonight and the laser was kept on the entire time the design was cut (i.e. Quote from sgraber on February 17, 2018, 4:02 am

Lightburn software full