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Torsion Box Design

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Forum topic by uMinded posted 06-25-2014 12:55 AM 1280 views 0 times favorited 9 replies Add to Favorites Watch
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uMinded

104 posts in 1319 days


06-25-2014 12:55 AM

Topic tags/keywords: torsion box workbench

I have just finished mudding and taping my garage (20’ x 22’) and have laid out how I want all my benches and stations. Now I am getting a preliminary material count and am stuck making the material choice for best support.

I have several locations where I want 6’ of unsupported work surface. My current design has aa 6’ 2×4 on edge with cross support every two feet. Then a sheet of 5/8 plywood to work on. This is strong but the overall benchtop thickness is over 4” and if I wanted to put on edge banding it racks up the cost of hardwood.

Do you think a torsion box made out of 1/2” ply on top and bottom and with 1/2” thick pieces of 3/4” on edge would be as strong over a 6’ span? What would be your go-to design for a 6’ span of workbench??


9 replies so far

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crank49

3981 posts in 2438 days


#1 posted 06-25-2014 02:29 AM

Four layers of 3/4” plywood (actually 23/32nds) glued and screwed, then topped off with replaceable 1/2” of MDF. Then banded with 1/4 maple. I put 12,000 lbs on mine with out any sag.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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Paul

721 posts in 1032 days


#2 posted 06-25-2014 03:00 AM

If you are in a new space I wouldn’t plan an any long term fixed benches. I would work on smaller portable solutions until you get your shops flow in order. In the first 6 months of my shop the design changed 4 times until I got the layout right.

Everything looks good on paper until you start to work with it physically

Paul

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uMinded

104 posts in 1319 days


#3 posted 06-25-2014 04:06 AM


Four layers of 3/4” plywood (actually 23/32nds) glued and screwed, then topped off with replaceable 1/2” of MDF. Then banded with 1/4 maple. I put 12,000 lbs on mine with out any sag.

Wow that would be a heavy beast and over $100 a bench, my 2×4 method is only $30 for a 6’ bench… I was thinking I could plane and rip some cedar fence boards for banding.


If you are in a new space I wouldn t plan an any long term fixed benches. I would work on smaller portable solutions until you get your shops flow in order. In the first 6 months of my shop the design changed 4 times until I got the layout right.

Unfortunately I need to use the garage for the car, planters and cold frames in winter so my layout is pretty tight. I have benches down each long wall and my workbench next to the window and thats all the “layout” as most my equipments is benchtop.

I might hold off on the built in’s just so I can get my workbench built and some house projects out of the way. I already have (4) 2 foot, (2) 4 foot and (1) 6 foot 2×4 with melamine portable benches in my basement to remove so its not like I couldn’t build anything until they are in.

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uMinded

104 posts in 1319 days


#4 posted 06-25-2014 04:07 AM

Have you guys ever made a torsion box with 1/2” ply?

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Crank50

173 posts in 1043 days


#5 posted 06-25-2014 02:30 PM


Wow that would be a heavy beast and over $100 a bench, my 2×4 method is only $30 for a 6 bench… I was thinking I could plane and rip some cedar fence boards for banding.

- uMinded

Well it is heavy, but that is the point. It is also stable and is 24” x 84” x 3 1/2” thick.
The plywood I used was 3/4” Sandply, the seven ply stuff HD imports from South America and it cost $27 per sheet when I bought it about 4 years ago. That put the price of my top at ~$60. Might be $75 now.

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ChrisK

1809 posts in 2549 days


#6 posted 06-25-2014 03:16 PM

uMinded, What gives the torsion box design its strength is the depth of the of the box. Using thin material to give the depth saves weight at the cost of size. The 1/2” top and bottom with 1/2” 3/4” on edge is not going to be very stiff. The 2×4 and 1/2 top is not a bad way to go. Cheap and strong enough. It will bounce a little if you hit a piece with a hammer near the middle. I would just build a quick temporary leg to add stiffness if I need it.

-- Chris K

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NiteWalker

2735 posts in 2044 days


#7 posted 06-25-2014 03:33 PM

My current design has aa 6 2×4 on edge with cross support every two feet. Then a sheet of 5/8 plywood to work on.
It works, so that’s what I’d stick with. No need for edge banding really, but if you want to dress the edges, cheap pine or poplar will do the trick.

-- He who dies with the most tools... dies with the emptiest wallet.

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cdarney

101 posts in 2498 days


#8 posted 06-25-2014 04:02 PM

I used 1/2 ply over a grid of 1/2” MDF. It’s about 3’ x 5’ with no problems. I did cover the top and bottom ply with some hardboard so that the surface can be replaced. If I had to do it again I might use 3/8 ply for the grid. I don’t care for working with MDF and the MDF makes it much heavier.

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MrRon

3927 posts in 2711 days


#9 posted 06-25-2014 04:43 PM

You could get a sheet of wall paneling, 1/8” thick and rip strips from it to use for edging on your 2×4’s.

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