Laser won't cut despite correct alignment and focus

I have a Boss LS laser, less than 2-months old, and I am at my wits end with it.

A little backstory - the machine had a faulty control board that led to the proximity sensor on the auto-focus not triggering and stopping the cutting table from driving the material up into the laser nozzle. I hit the emergency stop, but not before it screwed up the alignment of the table and the vertical alignment of the head. I followed Boss's instructions to realign the vertical and to re-level the table. It is not perfectly level, but all four corners are within ~0.3mm of each other. But since replacing the control board, the machine has needed constant adjustment to keep it cutting, and some days I can't ever seem to get the settings correct. Then, last Tuesday, I turn the machine on and it seems incapable of cutting through a board at all and it has a wider than normal cut, despite the fact that the previous day it was working and cutting fine. I fiddled with it all day Wednesday and get nowhere. And then on Thursday it suddenly cuts again just fine. Then on Friday it was back to fat cuts that won't go all the way through.

It engraves beautifully, and line work is crisp, but it won't cut for the life of me. I have tried lowering speed, increasing power, doing multiple passes. Nothing. I can put the same 1/8 birch ply into my Glowforge and it cuts beautifully, so I know it is not the material. The focal ideal point seems to shift daily from ~7.2mm to 10mm. I clean the mirror and lens every day - so optics are clean. I went through a total alignment check and everything is spot on with the mirrors. I have attached a photo to see how the engraving is crisp but the cuts are not.

Boss tech support has been very helpful in trying to solve the problem - but I just feel like I am not getting anywhere. Any suggestions would be greatly appreciated!

I think you have everything covered except for the wood. Beam diameter doesn’t change significantly with power however when the beam hits something it can’t burn thru it tends to widen. Like taking a touch with a focused flame and lowering it to a metal surface.
Cut and finely sand a test sample to examine how deep the beam penetrated and why/where it struggled.


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I am using the same wood I had always been using, and the same cut speed that I had honed in on when I first got the machine. It is the top lazer-grade wood from MacBeath hardwood, so it is a really consistent material throughout the wood. And my Glowforge cuts the same wood (I even tried the same sheet that my Boss failed to cut), using the same Glowfroge settings for that material.

If all of a sudden it isn't cutting through the same material that it had been before, does that suggest that the machine is losing power - either from the tube or the power supply unit? I can try to slow down the cut speed even further. It has a 105w tube, and when I first got it, it cut absolutely perfectly through the wood at 35mm/s with 75max/55min power. I bumping the power in intervals of 5 to 95 for both the max/min and reducing the speed of intervals of five all the way down to 20 mm/s. But nothing seems to resolve the issue.

You would have to ask the manufacturer about defective PS or tube. All that requires special instruments so they would probably ask you to ship it back, which is no easy task.
I doubt that the tube is bad if you can focus if that well. Overall your approach is good but hard to tell if your missing something.

I’ll offer one more tip that you will probably also ignore. Get a thick block of a clear resin. Something you can laser cut and see in from the sides. Either test fire or cut along the top and examine how far the beam travels into the block. Do it at different power setting and with both machines. Penetration, or lack of it, is the end result of all those components you think may be bad.

Tip: Problem solving is very different from completing some daily task. Solving problems requires you to think outside of the box and be willing to experiment.


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Resin specifically, or just something clear? I have some clear acrylic cubes I could run the laser over and see what it does.