Hi there,
I built out a CNCable 30" torsion box recently. I made a grid of 7 by 7 struts from 1/2" MDF, with cross-halving joints and I built the struts to total 2" in height. I then have a 1/2" face and base plate. The faceplate has holes to allow the struts to pass into the structure, locking the face in position. The baseplate does not have holes for every strut, but has some corner holes to locate the struts, so there's some inherent geometry difference there. Finally, a large grid of bolts and threaded inserts are used to 'sandwich' the plates together over the struts. No glue is used.
When attempting to mount routed panels to the side of the torsion box, there was an immediately obvious difference of about 1/8" between the corners of the torsion box, and the center, bowing towards the baseplate. I can rule out the CNC'd parts being bowed. So my assumption is that my design method introduces some level of stress into the structure.
The second issue I'm facing, is that when any adequate weight is placed on the structure, there is a large amount of creaking. It can either be the screws I use, or the MDF structure itself rubbing.
Does anyone have some tips for me to combat these issues?