One of the main features that I wanted to include with this laser was the ability to focus with software and/or to be able to autofocus. In the previous version, I had to use a use a distance block to focus and for different types of engraving or etching I would just sometimes have to eyeball it. That was not really great in the repeatabiliy department. Now with a z lift table I can just put a piece of material in and just press start.
I did alot of research when it came to laser z axes, and there are a few different designs out there which had pros and cons about each one. I am not a huge fan of the scissor lift type, because I feel that the lift height to complexity ratio is not there for me. In the end I settled on just a simple screw lift with bearing rod stabilizers. Some of the factors that went into my decision was that i sometimes engrave heavy objects (granite tiles etc) so I needed a robust solution. I also wanted to be able to have a fair amount of travel so that I could etch larger objects or use things like pin stands for laser origami or whatever.
I had alot of t8 leadscrew lying around as well as some 8mm hardened rods and supports. By using four leadscrews, I was able to independently level each of the corners. Each screw it supported top and bottom with 8mm flanged bearings and kept in place with a 8mm cuff on the top and a 32t gt2 pulley on the bottom. They are all ran from a single belt through a pair of idlers to the motor with a 16t gt2 pulley. This gives me a 2:1 advantage for torque lifting heavy objects. Because the motor is in a small area in the front used for venting, I suppose that I could have gone with a nema 23, but that seemed like a bit of overkill and besides I had a pile of 17s lying around, so that seemed like the obvious choice. Waste not, want not, make cheap laser or something like that…
