I have the xTool D1 pro with the 20w laser. I have been trying to cut through 5mm hardwood ply.
I did a test by cutting a circle and I had the power at 100% and the speed at 5, it cut through in 2 passes, the circle was about 30x30mm.
I moved onto a larger project which was approx 340x120mm. I used the same setting, but when I got to about 60-70% done the machine stopped and gave a warning constant bleep.
I think the alarm is saying it detected fire, however there was no fire. This was on the first pass.
It would be helpful to copy the Console messages here to help isolate the problem.
The fire detection message should be unambiguous, although it can be triggered by anything from bright sunlight to the usual fireball generated around the laser beam while cutting. Setting the detection threshold higher usually resolves the problem.
Aaaaand the laser head may be shutting down due to thermal protection: the laser overheats while running a long project at full power. I don’t know a thermal shutdown generates an error message or just turns off, but several other folks seem to be having that problem.