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Quick Torsion box question

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Forum topic by depictureboy posted 01-27-2010 05:36 PM 1267 views 0 times favorited 8 replies Add to Favorites Watch
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depictureboy

420 posts in 3106 days


01-27-2010 05:36 PM

gonna take the plunge and make a torsion box for my assembly table in anticipation of the upcoming remodel….question is If I get 2by material and rip it all to 1/2 inch thick then grid and glue it to 1/8 hardboard, will that be solid enough? I dont plan on banging on it or anything(that I know of) I just want to have it as a dead flat assembly surface…

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.


8 replies so far

View John Ormsby's profile

John Ormsby

1283 posts in 3200 days


#1 posted 01-27-2010 05:45 PM

MDF would be the best material to use. It is very stable and makes for astobg torsion box. I made mine 4’ x 8’ and is about 6” thck. Make your cubes about 7” on center. You will have a very flat box when finished that will be able to take a lot of punishment. How flat it will be depends on how you set up the base when assembling. It is also extremely important to cut all of the pieces the same width when ripping. Rip them all at the same time on the table saw. Any deviation in width of the material will result in a surface that is NOT flat.

Good luck on the build!!!!!!!

-- Oldworld, Fair Oaks, Ca

View Sawkerf's profile

Sawkerf

1730 posts in 2531 days


#2 posted 01-27-2010 05:48 PM

Ripped down 2x stock probably isn’t the best material for a “dead flat” torsion box. The grid needs to be very precisely cut and assembled – and needs to stay put after it’s built. I would expect the ripped down stock to wiggle, twist, etc after a while.

I would make my grid pieces from a decent grade of 1/2” or 3/4” ply, and take the time to assemble it on a carefully leveled platform before putting on the skins. If you can find it, David Marks did a show on building a torsion box assembly table a few years ago. Lots of fit and fiddle work, but his came out dead-on.

As John says above, MDF would be a good grid material, too.

-- Adversity doesn't build character...................it reveals it.

View PurpLev's profile

PurpLev

8523 posts in 3112 days


#3 posted 01-27-2010 05:51 PM

I’ll second John… go with MDF as it’s a stable material.

2×4s will change with humidity, and the 1/8” hardboard will not have any strength to balance that out and will warp with the movement of the 2×4s which will contradict the purpose and concept of the torsion box.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View MarkwithaK's profile

MarkwithaK

370 posts in 2641 days


#4 posted 01-27-2010 05:53 PM

I won’t profess to know the advantages/disadvantages of all the various materials but for mine I used 3/4” MDF for the top and bottoms skins. For the grid I used 1/2” MDF. Covered the the top with 1/8” hardboard and so far it’s been great.

-- If at first you don't succeed then maybe skydiving isn't for you.

View depictureboy's profile

depictureboy

420 posts in 3106 days


#5 posted 01-27-2010 06:03 PM

forgot about plywood…so I should use plywood for the internal ribbing…

the reason for the hardboard over the mdf is that I need it light so I can move it around easily and hang it on a wall when not in use….

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.

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Sawkerf

1730 posts in 2531 days


#6 posted 01-27-2010 06:31 PM

Talk about timely, the March issue of Wood magazine has an article about building a torsion box assembly table.

-- Adversity doesn't build character...................it reveals it.

View depictureboy's profile

depictureboy

420 posts in 3106 days


#7 posted 01-27-2010 09:16 PM

doh…ill have to look at my issue more carefully….I think I have that issue in my reading room…..

-- If you can't build it, code it. If you can't code it, build it. But always ALWAYS take a picture.

View sIKE's profile

sIKE

1271 posts in 3217 days


#8 posted 01-27-2010 09:42 PM

You want the best of both worlds rigidity and lightness. The problem being anything that is a 1/4” thick is going to have flex in it over the length of the grid. Best bet is to make it as small as feasible and still be useful and use the 1/2” mdf for the ribs and the skin. The mass/weight is a part of the formula….

-- //FC - Round Rock, TX - "Experience is what you get just after you need it"

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