Cabinet doors warping?

[Darrell Jones]

Hello,

I've finshed up some utility cabinets and made the doors from 3/4" hardwood plywood (same as the cabinets) and the larger ones are warping. Everything was painted inside and out. The plywood is cabinet grade from Home Depot, nice looking stuff made in China. Any ideas to help me out? Thanks.......DJ

[Jim Becker]

Darrell, unfortunately, the problem is likely the material. About the only way to fix outside of replacing is to put some reinforcement on the back of the doors if you can fit that into the mix.

[Mike Cutler]

Darrell

A few years back I bought a bunch of HD plywood. It was beautiful stuff, gorgeous actually.
I made shop cabinets, outfeed tables, storage boxes etc. I'm sorry to say that almost all of it eventually ended up at the recycle center. The only project that has survived is my CMS stand. It is all framed panel construction, and the ply couldn't warp.

Sorry to be a bummer, but I bought about 10 sheets at $28.00 a sheets, and I feel your disappointment. I'd say 8 total hit the dumpster.:(
If you can pull the ply flat, frame it, and apply some rigid strongbacks, you might be able to save the project

[David DeCristoforo]

Sorry about that Darrell. But like Jim said...it's in the material. Not all plywood is "created equal" and the stuff you get from HD is not "cabinet grade". At under $30.00 per sheet, this is no where near "top quality" plywood. It's probably fine for making "cases" but for faces, you need better material than that.

YM

[Peter Quinn]

To be honest Darrel I'd be supprised if plywood from the home depot did not warp. If you look closely at the core veneers in the Chinese "HD cabinet grade" plywood they are rarely even in thickness and often fold one over the other like some geological artifact! I've seen it spring and bind going through the TS like tense hardwood and have had problems with the face veneer delaminating in large areas. If you look closely you will notice there is no grading stamp to insure that some generally accepted standard has been applied to their product. See link below.

I'm told its produced at such a rapid rate that the glue is not allowed to cure in the press and it often leaves the mill still wet at the core. To further irratate things you can't count on the drones at the borg actually handling the product correctly once it is received. I have relegated its use to shop grade storage projects and never use it for jigs or fixtures.

I don't thing there's much plywood on the market that doesn't stand a chance of warping (though none nearly as bad as the HD chinese stuff) and its never really been my first choice for large doors. Might I suggest remaking the doors to salvage the project, perhaps using a melamine or thermofoil product with a particle board, mdf or lumber core?

In any case expect to pay between $45-$75 per sheet for true cabinet grade plywood. I typically use C-3 maple or poplar for paint grade work. I would look for a source that supplies professionals for use in any projects whose accuracy and appearance you care about.

http://justwoodworking.com/charts/hardwood_plywood.php