I know diddly squat about stresses torsion ... etc etc etc so if I am out of line here I'll shut up. The Mechmate Machine is a real beast and that runs a heavy steel Y axis Gantry on Hepco style V wheels (size 3) and they grind a V onto the top of the Angle iron leaving a 1mm flat surface on the top. There are a whole load of those beasts cutting 8' X 4' sheets and bigger in commercial operation