Hi!
I'm currently working on the first steps towards designing a 3 axis CNC mill and have a pretty basic question regarding linear rails: What should I screw them to?
As far as I understand linear rails they are best used fully supported and that supported materials should be what gives the system the "flatness" constraints. So I need some kind of pretty flat materials that has good dimensional consistency between different parts to mount my rails to. I sadly don't have the tools to machine a material flat, so I'll probably be stuck with some kind of aluminium extrusion.
What should I use? Simple square tubing or one of these extrusions with T-channels on all sides? Or should I bolt raw plate to the frame and attach the rails to that?
I'm basically asking: an what type of aluminium should I expect the best tolerances out of the box?