Hi,
I see that you gave a lot of thought on the design. Where are the pictures from post #16, i dont see them?


-3mm is ok for threading, of course the thicker the better :-) , but rails can be bolted on 3mm profile.

-i see some I beams on your last table picture, under the top. I beam is way weaker than square or rectangular profile, though looking at it seems stronger. I don't see where and how in a CNC structure we can benefit from using I beam. It twists like crazy, its relatively heavy for what it offers and so on... I would revise that part. use the calculator and see for your self.