Right off the bat I'm going to say - Safety, Safety, Safety. Job one, two and three. I have been thinking about building a CO2 laser cutter for a while and some questions have sprung up that I don't see quick answers for on the internet. I want a fast motion system which has pushed me towards belts. I am very interested in CoreXY but see no laser machines using it. Bad idea? I've seen some amazingly fast CoreXY mechanisms. Would mirror alignment suffer? Sizing the mirrors - how do I go about that? I assume it is a function of the laser tube itself. In all the builds I've looked at, no one ever seems to mention mirror size. Focal Length - I think 50mm is about right but don't understand how you decide. Longer means straighter cut walls? The longer the FL, the higher the mirrors (er, lens?) need to be above the material surface - right? I'm thinking about a 100W tube. My goal is to eventually get to PPI raster etching capability.
CoreXY = Bad idea, sync left and right with a driveshaft. If it skips, gantry goes skew, laser misses mirror (best case) or hit mirror at unpredictable angle (worst) and either something catches fire, or someone goes blind. So no CoreXY, no dual-motors, no chance of the two moving at different rates ever Size the mounts that fit nicely in your machine, buy mirrors to match. You are only aiming for a 6mm dia target on the mirror center after all. Get Molybdenum mirrors, worth every cent. 25mm is pretty standard for the flying optics, with usually a 20mm on no 3 inside in the laser head - check the hardware you buy though (mirror mount and laser head kits) All correct, but longer focal lengths are a pain to do engravings with - or etching off a layer off 2-layer signage material, etc Short focal lengths better for that tasks. 2-3" focals are pretty standard, add an adjustable bed so you can not only adapt to different focal use cases, but also material thicknesses
