Reinforcment for a 10’x4′ plywood door panel

Hi,
I would like to know if anybody has any ideas to keep a large plywood panel from warping. I will be making a 10’x4′ plywood panel door, 2- 3/4″ sheets adhered together. It will be a sliding door. I was thinking of a metal T edge band but maybe somebody has a better idea and if my idea sounds good, where can I purchase this type of band.
Thank you,
Scott
Replies
Scott
Check with a good steel supplier (Alro is one in our area)
they will also carry aluminum.
here's a quick search example from a supplier .
http://www.bonlalum.com/extruded-aluminum-products/standard-shapes/aluminum-tees-zees.shtml#tees
ideally it would have a barb on the leg, but if not I would think you could mill it.
I'm not sure about your edging idea. It would have to be very stiff to resist even the minor force generated by a 4 x 10 foot panel. Better to concentrate on building a panel that doesn't warp. I believe that the very best thing you can do to assure success it to use quality plywood right from the start. It the stock you select has any warp at all, then reject it. Marine ply is usually very good material. I recently bought some Hydrotec ply that is great looking stuff. But it is expensive. You can probably do as well using mdo which is usually available from any good lumber yard.
You didn't say how thick this door is going to be. But if you have some thickness to work with, then a torsion box sort of construction would be the ticket. You could use foam or the honey-comb material as the core. Use of a vacuum press will make assembly easier. You will of course need a very flat work surface on which to assemble the door.
use premium grade plywood and control moisture
Any moisture content changes in your plywood can wrec havoc on your doors ability to stay in-plane. I would recommend using a cabinet grade 3/4" plywood with as many ply layers as possible; say like a 13 ply baltic birch. Using this type of plywood will not eliminaete, but rather will minimize the risk of warpage.
FWIW, I agree that edge banding (with wood, alluminum, or steel) will do very little to structurally resist out-of-plane- warpage in the case of moisture content fluctuations. That resistence will have to come from the abliity of the bonding materail (adhesive) to resist and balance expansion and contraction of wood fibers at each layer... and your ability to continually control moisture content from manufacture fthrough service. That is easier said than done.
Thanks everybody for your replies. I understand the need for a high quality ply and thank you for your select suggestions. It needs to be an oak finish, no panels, and it isn't painted. I will research your ideas.
Thank you,
Scott
door panel
Scott, you might try a channel type edging instead of a "T" type. It shouldn't be too hard to find one w/ the correct I.D. (1 1/2"). You can then finish to suit, or might even be able to find a finish that would match your finish. Exterior cabinet grade oak ply would be the best material for what you're doing, assuming this is an exterior/entry type door, otherwise cabinet grade would suffice.
Good luck,
Geoff