Putting a torsion box under the ox is a super idea. Most tweaking issues start by the foundation being uneven or not level. With this you start with a truly level build surface.
Beaver's OX 1500
Build in 'Cartesian Style CNC' published by Dominic Ross, Oct 6, 2015.
OX 1500mm x 1500mm w/1.5Kw Water Cooled Spindle & VFD ran by a Gecko G540 & Mach3