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Re: Torsion Box Parameters?

Alan in Little Washington (NC)
I've been out of the country so a bit late to the parade.

A narrow (small closet or 1/2 of a set) hollow core door properly sealed and non-slip strips or carpet on the surface is the way to go. Most of them have a very thin, heavy-duty paper or cardboard web inside and thin skins, so overall are extremely light but plenty strong. Use one with birch ply rather than hardboard (Masonite) skins for better durability and resistance to weather.

I wrote an article for American Woodworker (Dec/Jan 2010) quite a few years ago now, about how to build a torsion box assembly table. My assembly table was much heavier duty, but in the article I also show an example of a torsion box I made entirely (skins & web) from thin, 3/16" hard board (and some leftover pegboard) held together with only yellow glue (I used halved joints on the web strips). It was 8' long, 16" wide, 2-1/2"(?) thick, but could hold 350 lbs of bricks center span with only 1/2" of sag! I used it as a scaffold plank for awhile until I got it really wet while washing my porch ceiling (the glue joints failed). Here is the link to the article and below it two photos of the partially completed and loaded hardboard torsion box.

Glue applied to the edges of the web and ready for second skin:

That is 350 lbs. of bricks! (two rows deep)

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