I amm planning on a 1200 x 1200 mm cutting area. I plan to build on top of a 200 mm deep torsion box. I want to use v rail as amy linear motion guides. Since it is backed up by the table, it should be stiff enough to mount on the sides of the box. But it would be easier to keep them parallel to the work surface and each other if they are lounted on the top face of the box. If I use belts for motion, would that be enough downward force to keep the gantry attached to the table? How else to apply that force?