Your LightBurn file is using several things that the LaserGRBL version isn’t, and those differences could be important:
- You have LightBurn set to 80%, and LaserGRBL set to 100%
- The feed rate in LightBurn is 200mm/min, and 300mm/min in LaserGRBL
- You’re using the M4 command (variable power) in LightBurn, and M3 (constant power) in LaserGRBL
- You have a start delay of 2ms set for each cut in LightBurn, and nothing in LaserGRBL
Those are possible issues, but I don’t think they’re actual problems in this case.
This is the GCode from LightBurn, run through a simulator:
And this is from LaserGRBL:
The reason LaserGRBL isn’t mis-positioning your parts vertically is that it’s running everything top to bottom and making very slow moves along the Y axis, whereas LightBurn is taking a more optimal path through the job that moves both X and Y more or less equally.
Even with a 50% faster movement speed, LaserGRBL’s GCode will take 15 min 49 sec to run, and LightBurn’s takes 12 min 3 sec.
If your Y axis speed or acceleration is set too aggressively, it’s much more likely to slip with the movement path generated by LightBurn, but you can see from the simulation that the code itself is not the problem. Lower the acceleration setting for your Y axis and I bet this misalignment goes away.