Another Torsion table question

LowRider CNC Advice
1

I’m planning to build a torsion table soon - 30x60 - for my lowrider.
I’ve read a few places that all you need for skins are 1/8". I’m thinking hardboard. What would rib spacing need to be?

Would 1/4" mdf be better? probably but cost more. can you use two different thicknesses? 1/4" on top and 1/8" on bottom?

I’m thinking of using 2x4 for the 60 length ribs. and 3/4" scrap particle board for the 30" width. the 2x4 would provide good anchoring area for screwing down a spoil board.

Trying to build this as inexpensive as possible but still have a good quality.

2

You can go thin for the bottom but on the top you really need something you can cut into.

3

Try to stick with man made wood for the ribs. A pine 2by will swell and contract more than plywood/mdf.

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4

To get the absolute lowest weight table, I’d use 1/4" or 1/2" ply for the ribs, 1/8" luan plywood (sometimes called “doorskins”) for the surfaces, then add a sacrificial/replaceable 1/2" or 3/4" spoilboard.

We used to build “hollywood” style flats in our college theater program from 1x4 pine on edge for frames, skinned with 1/8 luan. They lasted for years (much more durable than old style canvas covered flats) but were incredibly light weight, and easy to screw through the frames for “permanent” sets, or just clamped together for quick changes or portable setups.

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5

Thanks guys, this is really helpful

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6

Any recommendations on rib spacing

7

Can you still find luan anywhere??? I’ve been looking for 1/4" and can’t find any. Unless of course you want the oak or maple for insane $$$$$$

8

Any cheap ply will do - MDF or hardboard will be just as good, but do seal the MDF for longevity.

9

I originally built my table for leveling my furniture designs’ legs. The table is so flat that you can’t slip a feeler gauge under any part of a 48" level at any location on the 48x60 top. Since I was using it as a working surface with metal legs, I needed the skin to be a bit tougher and resistant to punching holes in it. I ended up using 3/8" ply but 1/4" would be fine. I suspect 1/8" would work if you don’t ever use it as a workbench and always have a spoilboard on top.

My torsion box used 1/2" ribs spaced 8" apart. The thicker material just makes it easier to hit with a nail. Scribing a line on the skins to locate the grid is super helpful in hitting the rib every time.

The beauty in the torsion box is how flat you can get the surface IF your ribbing is flat and straight. You’re better off ripping 3" ribs from plywood rather than trying to use solid wood.

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