Question on bookshelf and torsion box


Hi all,
I'm in the middle of designing a bunch of furniture for my office (3 drawer boxes, 2 desktops, 2 bookshelves, 3 wall cabinets).
I got the basic ideas from a book I bought on office furniture. The authors basic desk design was to create torsion boxes for the desktop, and lay them across drawer boxes. His design for the desktops was a torsion box with 1/2" skins and 1" ribs, making them a total of 2" thick. The drawerboxes will be a total of 28" high, so the total desk height will be about 30" high.
I've gotten the 1/2" ply for the bottoms of the desktops, but when trying to find 1/2" oak ply for the top skins, I can't find it in my home center, and the other suppliers are asking more than I WANT to pay. Now, my local home center happens to have some pretty nice 3/4" oak ply right now, (and it's less expensive than the other supplier's 1/2" oak ply), so I'm wondering if there is any reason that I can't use a 1/2" bottom skin and a 3/4" top skin. It seems to me that it should still work fine, but I just wanted to double check and see if there were any 'gotcha's' that I don't know about. I'm still planning on staying with the 1" high ribs, so the overall height will increase by 1/4", but I'm kind of a tall guy, so a slightly higher desktop won't hurt.
Second, I'm building the bookshelfs in two parts, an upper and lower to ease moving. The top and bottom will be bolted together with furniture connector bolts.
The units will be 3/4" oak, 36" wide. I'm currently planning on making both halves 42" tall. Is that short enough that I won't need a fixed shelf in the middle of each half. If not, what is the max verticle height for a bookshelf that size where I wouldn't need a fixed shelf. There will be a 1/4" back on each half of the units, glued and nailed into 1/4"x3/8" rabbits.
Thanks in advance!!!
Trace Wilson
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Trace Wilson wrote:

The only problem I know of is that the inexpensive plywood carried by home centers tends to be notoriously crappy. After doing a search here on "Borg" and "plywood," I decided that I would use that stuff for jigs and fixtures only. For 3/4" cabinet-grade oak ply, I'd go to my lumber supplier and pay $65 or $75 per sheet.
I've heard that a Borg will sometimes get the odd shipment of decent stuff, but it seems to be accidental.
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"notoriously crappy" often, sometimes, usually, means that there are voids under the veneer. In many applications, this isn't a huge problem. In shelves and desktops, it is a failure waiting, sometimes not very long, to happen.
The desktop holding the computer monitor I'm looking at right now has two of these void blowouts, patched poorly with a filler putty. The only good part of this is that I didn't build the desk.
A sheet of glass made to fit is a LOT more expensive than a sheet of good quality plywood from a professional supplier.
Patriarch
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drawers). What the other place sells is furniture grade which meets a higher standard.... So, you get what you pay for. Jim
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Jim wrote: <SNIP>

Thanks for the thoughts on the wood, and yep, I understand the possible risks. Since no one has made mention of any structual issues with the designs, I'm assuming I'm good to go there?
Thanks again,
Trace Wilson
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