Unwarping plywood core via laminating... can it be done?

I am working a scratch build where I have cut three 1/8" plywood fins and intend on laminating 3/32" balsa to both sides.
But, upon cutting the plywood cores, they have warped. It might be the high desert air here.
I am considering going ahead and laminating the balsa to the fins and keeping it in a press, using white glue
instead of epoxy, in an attempt to get the fins back to straight. Has anyone done this?
Yeah, I am being kinda lazy. I can cut new fin cores out of better stock.
TimE

You'd be better off having the plywood flat to start with. Laminating balsa on it between flat presses won't result in a flat fin, just a flatter fin. It will bend back a little when pressure is removed. It becomes a stressed structure, that will change shape as humidity changes, possibly as temperature changes over a wide range, and certainly as the balsa is sanded!

Gerald

I agree with G_T; I don't think the balsa has enough rigidity to keep the warp out and you'd be better off starting with a flat core.

That said, you can sometimes flatten warped plywood with steam and pressing, but I would try that before laminating the balsa.

I' have had success with misting the plywood on both sides with Windex, setting it on a counter with the bow raised up in the center and stacking weights on it.

Interesting read, some plywood fins I ordered from the laser cutter turned up warped….

What's more annoying is I only ordered them because 2 of the 4 balsa fins I cut and started to glass became badly warped

I wonder what the RC plane purists might have to say, they play with this stuff a lot more than we do. (think of all the light wood they use for big scale airplanes)

RC Forum research?

Scott Evil said:

I wonder what the RC plane purists might have to say, they play with this stuff a lot more than we do. (think of all the light wood they use for big scale airplanes)

RC Forum research?

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I am currently building my first scale rc aircraft, and whilst it is a decent size 60" wingspan, the size of the parts used to build are not particularly wide, never something as wide as a fin.

Also, I was discussing accuracy of parts with a friend who has built RC aircraft for decades the other day and he made the point that whilst rockets require the closest of accuracy during construction, aircraft can tolerate numerous inaccuracies in building as well as compensating for these with trims and pilot skill.

Tiger said:

I' have had success with misting the plywood on both sides with Windex, setting it on a counter with the bow raised up in the center and stacking weights on it.

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I've had some success as well but it can be hit or miss. Better luck by over correcting and splitting the difference.

via Forumrunner/GS4

I've had stuff warp before when I have been fibreglassing. Once I glassed the other side it evened out. Luck of the draw I suppose

If you apply a veneer to one side of a board, it is not a matter of if, but how quickly that board will warp. I would think the same applies here. And that it would be best to keep the item under a press until both sides have been glassed.