Hi. Is there any reason folks build torsion boxes the way they do? I get the perimeter frame, but why all the internal pieces? It would be far simpler, and probably more rigid, to fill the internal space with foam sheets. This is how many aircraft wings are constructed (using as little as 3mm ply…

That’s a very interesting idea. I built a few R/C airplane wings similar to that, way back in the day. The skin was balsa, overlaid with fiberglass, and those wings were darned strong. I built my 1F torsion box the conventional way, from 18 mm BB ply, following “stressed skin structures” design g…

I fully agree about the hard points.

Hey Duncan, [image] rtfm: It would be far simpler, and probably more rigid, to fill the internal space with foam sheets. This is how many aircraft wings are constructed (using as little as 3mm plywood skins top and bottom). These wings bear thousands off kilograms when pulling high G forces. …

Superb! But using foam panels is both cheaper and easier to build. The foam/ aluminium honeycombs / wooden batons internally serve one purpose only. And that is to keep the upper and lower panels apart. Even pasting ordinary A4 paper on either side of a foam sheet turns the wobbly foam into a rem…

A Cracking idea. Two people could hardly lift my torsion box when I built it using 1 inch mdf top and bottom and batons (i wont do that again). Things i would consider: allowance for fixing (mentioned above) and bonding the layers. A thought: sometimes the mass of the unit may be helpful when mi…

Torsion boxes depend on the internal grids for carrying loads and resists bending. While foam adds significant rigidity, it is far less effective in carrying the loads. For light and evenly distributed loads, simple foam with plywood skin works well.

Sorry to disagree. The internals of a torsion box have one job - to keep the outer panels apart. As the box tries to “bend” the outer panel stretches, and the inner panel compresses. The internal structure simply keeps these two panels from collapsing onto themselves. This is why airplane wings …

Hey, interesting concept. On a 4’ wide machine you will get deflection. You want the top to be as rigid as possible. My thoughts on the torsion box are they are unnecessary for the application of cnc top. I built essentially a 2x4 “wall” studded at 12in o.c. And sheeted the top with 1in mdf. This wa…

Torsion box question

349iq2345 September 14, 2024, 4:34am 4

Hey Duncan,

what about this?

Aluminum Honeycomb Composite Table for Journeyman - long post w/photos

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Torsion box question

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