Hi Ellis, welcome to the forum. For the size that you are building, and the materials you wish to cut, I personally think it would be worth thinking about a fixed gantry rather than a moving gantry. With a machine like that and 20mm rails and a single 20/25mm central ballscrew I think you could build a really rigid little machine that would suit your requirements, but would of course require a longer X axis. Good luck with whatever you decide, keep posting your designs and thoughts and some of the very experienced members here will offer all the help you need. G.