I'm designing a 4'x4' gantry style router. My initial thoughts are to use 80/20 extrusions for the table frame with ply or mdf bolted to the top and bottom for rigidity (torsion box). Linear rails will be bolted to the 80/20 to support the gantry. For a little more effort and a lot less money I'm starting to think that structural aluminum u-channel could replace the 80/20 in this application. How straight is u-channel out of the UPS box compared to the equivalent 80/20 extrusion?
TIA
Steve T.