GCode for Mach3 PMDX126 Board

I have a CNC 1300x850 that I built and it is controlled by Mach3, PMDX126 board, 203 Gecko drivers. I have a Jteck 3.8w laser that I made a shoe for to hook to my spindle. I control the laser (on/off) with pin (switch) 14 on the PMDX126 board. I have a post processor that I got from Jteck, the M10/M11 one and keep getting burns on the start / stop points. I saw that Lightburn gets the machine moving before it turns on the laser. My thought is to have Lightburn make the Gcode that I can read with Mack3 to run my table. Is this doable?

Not likely, no. LightBurn doesn’t support Mach3, and normally uses spindle speed to control the laser power output, and the coolant mist / flood commands to turn on / off the laser (M03 / M05).

You could run a script to do the command substitution you need, but it’s not something that can be done from within LightBurn at this time.