When placing parts into a laser machine the first step is normally to set the height of the work so that the laser dot can focus on the exact spot that the cutting laser will hit. The dot lasers are mounted off to the side at an angle, it would be ideal if the aiming laser could be mounted directly above the work but of course this is where the cutting laser lenses are located. Rich Olson from Nothing Labs has come up with a way to determine the laser strike point regardless of the height of the work. He has done this by replacing the existing dot laser with a line laser and mounting a second line laser onto the cutting head. I think this Laser Cutter Cross Hair Alignment System should be standard equipment on all modern laser cutters. I know that I have goofed a few times when I have positioned the work before setting the table height correctly.
Via: Hack a Day