Torsion Box Table Top Build


Been doing some research as of late on what type of table I’d like to build. I asked the question of ideal size not too long ago and I’ve decided to build a 4’-0" x 6’-0" torsion box table. My mom works for a custom cabinet and door company so I’ll luckily have access to a CNC to get much of the materials cut. There are some really clever plastic legs that I recently saw in another table build (thanks, @AndyF) that I’ll use in conjunction with this top.

I’ve decided to use 1/2" mdf for the build. I’m not sure how heavy this top will become. I don’t have a proper mdf material setup in Inventor, but based on the model I’ve created using oak, It’ll be some where in the ballpark of 150 lbs (see table below). Does that seem like a lot for a torsion box of this size?

The spacing of the internals is set to 6". Is this overkill? I read in another post that there isn’t a magic number for internal spacing. Obviously if I upped the spacing, I’d have substantial weight loss.

Also, does anybody have recommendations for my half-lap tolerances? We used a caliper on some 1/2" mdf stock at her work and we got .500 bang on. Because we have access to the CNC, I want these joints to as precise as can be.

As always, thanks for the help everyone! Keep up the great work!

Assembly Properties

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@AngusMcleod, cool, thank you! Good idea on the doublers!

I’m not sure if a 1/32 tolerance would be enough? Especially because you need to weave/lock so many internal pieces. Thoughts?

I built a 46x46 out of 3/4, 7" internal spacing. I didn’t half lap, I just glued and Brad nailed slats…

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48" x 50", 3/4" MDF, Offset 8 1/2" internal spacing. No lap, glued and screwed.

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Assembly Drawing v1.pdf (168.4 KB)

That’s how I laid it all out.

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The fact you can get this done at a shop is fantastic. I’m sure it will turn out perfect.

I had really good luck with Baltic birch. It takes to kreg screws better than anything and little risk of splitting. Heavy but extremely durable.

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@RobertBeattie, cool! did you use extrusions for this?

Upon review, I’m not sure those clever plastic legs will hold up how I’d like. I’d also like to include wheels in this build as well. That said, I initially had planned to make the completed table top thickness at 3 1/2" to properly integrate with those legs. If I were to adjust the overall thickness of the table, I could definitely save some weight there too.

Is there too small of thickness that I should look out for? Now I’m thinking of using a 1/4" bottom section, 2" side boards and internals, and a 3/4" top section to give me a 3" total thickness. Thoughts?

I built my base as well. I used 4"x4"s that I think I may have ripped and cut notches into to set an upper and lower apron of 2"x4"s. Later on, I installed 2 ‘joists’ into the bottom apron and put plywood on it to use it as a shelf.

Base Drawing v1.pdf (165.3 KB)

Leg Drawing v1.pdf (156.0 KB)

The legs probably should have been shorter, but I manage alright as is. I added the casters that have the lever that you step on or lift to activate and retract.

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