Please explain how to use the square to align. Mine is off enough that multipass cutting is generating wide angled slots.
A machinist friend has volunteered to mount a mirror on a 45 degree cut in a rotating vertical shaft. Idea is to shine the laser onto the "exact" center of the shaft and measure the burn on a circular wall. X+, Y+, X- & Y- should all be the same if it is vertical. Hoping that there is a math algorithm to evaluate the results and compensate for the beam not being dead center.
All of this needs to be done on a flat work space! You need a square and an accurate measure.
First remove the gantry. Then use the square to make sure the frame is flat and all corners are 90° take the feet off. Then make sure all the feet are touching and the table and is the same height at all corners. Use the square to make sure both gantry sides are 90° to the X axis beam, you need to loosen or remove the lower wheels. Now make the X axis beam vertical. Set it on the table and make sure it is sitting flat. Then use the square. You will be testing this beam again for vertical after you remount the gantry. At this point you will reinstall the gantry, everything should be straight and level to the work top. Check the X axis beam again and see if it is still vertical. Now check both ends of the beam and make sure they are the same height from the work top. Now you are finally at the point of adjusting the laser module. Put your square on the front of the module to see if it is vertical. Now put your square on the side of the module and make it vertical. Your machine is now mechanically true. The only place it can be out now is if the beam out of the module is not square to the module body. Or the lens is wobbling.
The only way to test laser beam true is to cut at several different heights and compare the cuts to each other. That will tell you if the beam is not true to the module body. Another test might be to dismount the module and set up several pieces of paper at different distances away from the module. Then burn through the papers and see if the beam is straight out from the module.