If you aren't already running Grbl 1.1f on your controller, we highly recommend it for laser use. This is not always true with other versions of Grbl. This also has the benefit that when the laser comes to a complete stop, the beam turns off (zero speed equals zero power), meaning that pausing a job automatically turns off the laser. Since the machine needs to slow down to take sharp corners, this means corners get over-burnt, while long straight lines end up lighter. Older versions of Grbl do not have this feature, and simply run the laser at a constant power output for the duration of a cut.

This allows the laser power to be adjusted up and down as the machine speeds up and slows down, making for very consistent cutting and marking.

The latest versions of Grbl (1.1f and onward) support a feature called variable power mode for lasers. Luckily this is easy to change, and easy to switch from one to the other. The 'standard' way a CNC machine is configured is somewhat different than the way laser machines often are. It is highly configurable, and this is both a blessing and a curse. Grbl firmware was originally designed for CNC machines and 3D printers, with laser support added more recently.

Set your machine status reporting to be relative to the workspace origin, not the machine origin ($10=0).

If your machine uses negative workspace coordinates you'll need to apply a workspace offset (G10 L2 P1 xx yy).

You might need to enable 'Laser Mode' if you have GRBL 1.1f or later ($32=1).

The value in LightBurn is called 'S-Value Max', in the Device Settings.

You might need to adjust your spindle max RPM value ($30) to match the LightBurn default (1000) or vice versa.

If you have a GCode-based system, like a Shapeoko, Eleksmaker, X-Carve, or Acro system, you might need to make some simple changes to get the most from LightBurn.

Lightburn cnc