multiple building boards

I'd like to work on different planes as the mood strikes. My problem is that I usually build on ceiling tiles on my only dead flat surface, my
workbench.
Is there some kind of building board that is flat, and will stay flat if you put it on a non-flat shelf?
Something I could put toghether myself maybe, such as a laminated basswood building board or something? I'd probably make a few of these up for whatever I want to work on at the time. If I'm working on a wing that isn't "safe" to unpin yet, but want to work on something else, I need to be able to put the building board someplace else that may not be flat for weeks at a time.
John
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I use blank doors, with foam, or cflex, on top.
A folding table from costco..the 6 footers...
my 2 cents

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Yup. I build on 2" pink insulating foam. You can buy a piece 8' X 2' for very little. I make 2 bds from this. It is dead straight and flat. Holds pins perfectly and weighs nothing. If you need a little extra holding power for something stick finishing nails in it. Anyway, once you frame something up on this, stand the thing in the corner and start on the next piece. Guaranteed it won't warp or change shape. Best thing I've ever used for building. Gord Schindler MAAC6694

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wrote:

Yes, but unless you want to pay for 1/4" 6061-T6 aluminum sheet and have it cut to width and length, you'll have to build something. Even the 1/4" aluminum sheet will sag over time.
Any of the hobby solutions to inexpensive building boards, e.g. celotex, building insulation foam, etc., will conform to the "non-flat shelf" after various periods of time, some sooner than others, and I don't think they'll serve your needs for a portable flat building surface.
The only 'board' I know of that will stay dead flat under almost any conditions is a torsion box.
Alas, most instantiations of torsion box building boards are large and decidedly heavy, so setting them aside on a temporary shelf doesn't work unless you've got a _lot_ of room and seriously sturdy shelves.
You could scale a torsion box down using thinner materials, but you'd still wind up with something that's heavy-ish and would need adequate, albeit perhaps not flat, support.
Most torsion boxes are built with 1/2" or 3/4" Medium Density Fiberboard (MDF), and that stuff is heavy. You can get 1/4" MDF if you try, and that might lend itself to a reasonably lighter torsion box, particularly if you limit the length and width. A torsion box made from 1/4" MDF, perhaps 4' long and 2' wide, would weigh in the neighborhood of twenty pounds.
While that might seem considerable, the resulting torsion box building surface won't ever likely warp or twist, ever.
The reason MDF is used is that it is thermally stable and doesn't seem to care about humidity changes. As such, it is an excellent material for building surfaces if you add a layer of something to handle T-pins (foam, celotex, etc.).
MDF is also the material of choice because it is assembled with common wood working adhesives and fasteners (pneumatic nailer is _really_ handy for MDF work). Titebond wood glue and a $40 nailer will do nicely. You can rent nailers if you don't have one.
See the photo album "Torsion box building table" on my web site. Then follow the embedded link to DIY Network to find the complete original torsion box series of shows/articles.
A word or three of caution . . .
If you've not worked with MDF, prepare for an education in dust control. The MDF dust is at least as fine as balsa dust and it is _much_ heavier. It clumps because of static charge and it _will_ cover everything in your shop. You also need a good grade canister-type respirator to keep the dust out of you. A throw-away painters mask is worthless. Decent canister-type respirators can be had for about $35 or so; the Advantage 200 is a very good mask : http://www.tools-for-woodworking.com/subcatmfgprod.asp?0 (6&1(7&2=-1&6=1
You'll need access to a reasonably accurate table saw. Building a torsion box isn't cabinetry, but it does require ripping long strips accurately - if the edges of the strips aren't parallel, the table won't ever be flat.
You'll also need three or four long-reach clamps, at least as long as your torsion box will be wide, such as : http://www.tools-for-woodworking.com/product.asp?068&169&3 (14
I used my 10" Delta bench top table saw to cut the MDF for my torsion box building table, and it was a real challenge keeping the heavy stock under control. You may be able to find a wood working shop that will cut the MDF to plan specs.
It's do-able, and you'd wind up with an almost indestructible building surface that is portable. Cheers, Fred McClellan The House Of Balsa Dust http://home.mindspring.com/~the-plumber
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I use a cheap hollow core door (between $16-30 depending on where you get it.) and cover it with celotex. Haven't had a problem for over 10 years with this and both of my doors have survived multiple moves including one from Hawaii ( hence the $30 door.). I can replace the celotex when it gets too raggedy or dented and the door stays flat on the aforementioned COSTCO folding tabel.
My first one cost less than $25 for the door and celotex.
Jim W

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