I'm looking to build my first torsion box for my CNC router. The dimensions will be 48"x48". I'm planning on using a 4" rib width for a total 5" thick torsion box. I'm going to use 1/2" MDF for the skins but was wondering about using 1/2" particle board for the ribs. I have a sheet of it already and would like to use it up. To me it seems like it would be strong enough when turned on end but I'm concerned about attaching it to the skins. Even a finishing nail will split it when hammered to the end. Has anyone used PB for their ribs before? What was your experience?