I recently purchased one of the cheap 40w lasers and while it works very well for the money, I have noticed that it's cutting power seems to vary. I can have a sheet of 1/8" birch and with max power, speed of 10, the first few pieces will just fall out at the end of the cut, the others are still very much attached and need at least one more pass to cut them. I was thinking mirror alignment, but check that to the best of my knowledge and all seems well. It also doesn't seem position dependent, it can be anywhere along it's path, even areas that cut clean on the last pass now will need a second pass. It is very hit or miss and I have yet to figure it out. I tried moving the focal point around, cleaning the lens and mirrors, etc, and if it all works fine after I'm done, and I think I got it, it will act up again shortly after .
A couple things to point out- when I took the mirrors and lens out to clean them, I noticed a chip on the back side edge of one of the mirrors and the focal lens has a nice chip in the edge as well. I don't see it being a problem as the chips are outside of the lasers path and I can't see that making it inconsistent.
Another is after using it for a few hours when I first bought it, their water pump screwed up and output got very week- assuming it overheated the tube. After a cool down period and putting their pump back together, it seemed to be working fine, but I don't know if overheating the tube once can cause permanent damage or not (no visible cracks or anything). Last problem was one day the meter started flaking out, then stopped working followed by the laser shortly after. Upon inspection, the blue wire that goes from the resistor to the end of the laser tube was pinched in the case during assembly, eventually shorted and completely burned through. It burned the wire in half and was arcing to the case pretty good too...
The seller has been OK for communication but has no real answers. Any thoughts from those in the know here ?