已采纳回答What you found is basically correct, so let me go through it point by point and help you narrow things down.
First, the silver focus bar should indeed be 50 mm long. I’d recommend measuring the one you have with a ruler or calipers. If it’s noticeably shorter than 50 mm, there’s a good chance it isn’t the original one or was swapped by the previous owner.
Second, the brass piece on the 10W module is part of the standard setup. It’s the connector between the air assist nozzle and the laser module. It’s not a spacer and doesn’t need to be removed. A lot of people assume it’s extra hardware at first, but it’s supposed to be there.
As for the cutting issue, if your test isn’t cutting all the way through, I’d check a few common things:
The most important one is proper focus. If the focus height is off, even running at full power won’t give good cutting results. Using the test-fire dot to eyeball the smallest spot can work in a pinch, but it’s not very consistent.
Next, make sure S Value Max in LightBurn is set to 1000. If this value is lower, the laser will never actually reach full power, even if you’re setting 100% in the job.
Finally, check the protective window lens on the laser module. If it’s dirty or contaminated with smoke residue or resin, you can lose a surprising amount of power, especially when cutting something like 3 mm wood.
Overall, what you’re describing sounds like a combination of inaccurate focus and reduced effective output. Once the focus tool is confirmed, the settings are correct, and the lens is clean, a 10W diode laser should be capable of cutting 3 mm craft wood without too much trouble.