Question about laminating 3 pieces of 1/4" birch plywood

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I'm making a book case for my daughter and she wants a curved top. I have made a form over which to do the bending but I am having a problem with the 1/4" plywood splitting. I can not use 3/4" plywood and make cuts in one side as both the top and bottom with be visible so I decided to laminate 3 pieces of 1/4" plywood. I plan to use polyurethane glue to do the lamination but I need to conquer this splitting problem. I would appreciate any help you can offer.
TIA.
Dick Snyder
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Dick Snyder wrote:

You should get some bending plywood which has all the plys running in the same direction allowing it to bend easily,
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Use bending plywood, and cover it with birch veneer.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Dick Snyder wrote:

What about kerfing the interior sides of the 1/4" plywood? The center piece could be kerfed on one or both sides.
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I tried cutting the interior side of one of the pieces of plywood with a utility knife. When I tried to bend the plywood it just cracked at one of the cuts. Maybe I will kerf it to see if that works any better.

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May be kind of dumb, but what about wetting it? Like sheetrock for an arch.
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I can't totally wet it as I have to apply polyurethane glue to some of the surfaces.

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So, why do you _need_ to use the poly glue?
Patriarch
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Maybe I don't _need_ to do it but I have been advised by others to use it to minimize the tendency of the wood to lose some of the bend so I am going in that direction unless I hear some reason to go another way.

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On Wed, 25 Oct 2006 13:29:43 -0400, "Dick Snyder"

You can't???!?!?!
Read the directions on the polyurethane glue.
Might be an eye-opener.
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I just re-read the directions on the glue. I am using Gorilla Glue by the way. It says dampen one wood surface and apply the glue to the second surface. The moisture activates the glue.
wrote:

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Dick Snyder wrote:

It should work bettter as a kerf removes material so that there is less tension on the convex side.
--

FF


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Still cracked. I am going to go with bending birch plywood and epoxy.

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On Wed, 25 Oct 2006 09:26:46 -0400, Dick Snyder wrote:

Watch the grain direction of the top sheet. You want to orient the grain so it is perpendicular to the direction of the bend.
Also, try bending plywood for at least the middle of the three layers. You may not like it for exposed surfaces. Doug suggested using three layers of this, and veneer for the exposed surfaces, which IMO is the way to go if you have a way to apply the veneer.
--
Art Greenberg
artg at eclipse dot net
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Dick Snyder wrote: I can not use 3/4" plywood and make cuts in one side > as both the top and bottom with be visible so I decided to laminate 3 pieces > of 1/4" plywood. I plan to use polyurethane glue to do the lamination but I > need to conquer this splitting problem.
Bending plywood and epoxy.
Poly isn't going to cut it.
Lew
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Get some plywood that can do that:
http://www.vandykes.com/product/02007822 / or http://www.bd-international.com / or http://www.boulterplywood.com/FlexiblePlywood_4.htm
Dick Snyder wrote:

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The problem I think will be that the book case has to be stained to match other furniture in the room that is birch. I'm worried that if I buy bending plywood, it will not match. Thoughts?

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I didn't read carefully enough before replying a few minutes ago. I see that Boulterplywood has a flexible birch!

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Another way to do this is to buy the flexible mdf and cover that with birch veneer.
That, of course will require a veneering vacum bag and pump.....
I would stick with the flexible birch from Boulter.
Glad I could help you...
Dick Snyder wrote:

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I visited Boulter today to buy bending birch as they are near the daughter for whom I am making the book case. I note that the bend puts the finish side on the inside of the curve. I need to have a finish side on both sides of the curved top of the bookcase. Can I bend the bending birch the other way without it cracking? I can of course just try it out but I'd like to get some advance knowledge before I waste some material.
TIA.
Dick Snyder

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