bending thin hardwood

Hi, I'm repairing a curved chair back, pic is at
http://camoo.freeshell.org/chair.jpg
I have some 1/8" thick red oak, there will be pieces about 15" x 7" screwed to the front and back of the frame that you can see in the picture. I cut one of those pieces, it bends fine to the curve of the frame. The grain of the oak will be horizontal on the chair.
The oak should be bent to the right shape before attaching it to the frame, otherwise it'll put a lot of stress on the frame.
I think I know roughly how to do this: I would trace out the curve of the chair back on 3/4" plywood and cut it to that curve; then clamp the oak between pieces of curved plywood to bend it.
How about wetting the oak before clamping it into the plywood mold? I tried this on a scrap piece and that seemed to help it bend. Should it be re-wet? I've heard of steaming wood to bend it, but that seems rather a pain.
Should the plywood mold have an exaggerated curve?
thanks Laura
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Yes.
Rather than a plywood jig, just prop the ends of the panel on 1" boards and clamp the middle of the panel to produce the curve. I don't think your chair's curve deflection is quite 1" and you will have some spring back of the panel, when you remove it from the jig.
Wet/soak the panel in hot water before bending it. That red oak might warp a tad, too.
Also, the ends of the panel might split, during drying, depending on your panel. Cut your panel 1/2" to 1" larger (width X length), bend it, then trim it to fit the chair. The trimming would get rid of any splitting, also, if need be.
If your red oak panel has been kiln dried, it might not bend properly. Air dried lumber is best for steam/wet bending. Is your panel plywood or is it a solid cut of red oak?
Sonny
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and clamp the middle of the panel to produce the curve. I don't think your chair's curve deflection is quite 1" and you will have some spring back of the panel, when you remove it from the jig.
It's actually 2" deflection at the center of the curve. Maybe it still could be clamped in that way? I thought that pressing on it with a straight board or clamp might dent the veneer.

a tad, too.

panel. Cut your panel 1/2" to 1" larger (width X length), bend it, then trim it to fit the chair. The trimming would get rid of any splitting, also, if need be.

Air dried lumber is best for steam/wet bending. Is your panel plywood or is it a solid cut of red oak?
It's actually some other kind of wood with an oak veneer - I didn't even notice that till now! It's meant as a cabinet piece, something I got at Lowe's. I wetted a scrap of it - not soaking, just wetting - and it did bend fine, although I didn't keep it bent while it dried, so I don't know to what extent it would keep the curve. It dried without cracking.
Laura
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On Thursday, December 27, 2012 5:40:12 PM UTC-6, Graven Water wrote:

At first, I thought it was a child's chair.

It is likely kiln dried wood. Multifold a towel and apply that to the panel, then your clamp or clamping board, to prevent your panel from becoming marred. Wet it and clamp it with a little deflection, at first. After an hour or 2, wet it some more and clamp down some more... more deflection. After another hour or 2, wet it and clamp down some more..... Creep up on the amount of deflextion you need, then deflect a little more, to accommodate spring back. You'll have to guess at how much spring back there may be.
Rather than repeated wettings, you might wet it and place a wet cloth over and under the "whole". When the cloth(s) dries too much, re-wet it/them. Your clamping process may require a 8-12 hour time period... go slow. It may be a hit or miss proposition with that ply panel.... and hope the plies don't separate/come apart in places.
Once you get to your max deflection, allow the panel to dry, in the clamped position, for another day, at least.
Good luck. Sonny
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On Thu, 27 Dec 2012 16:35:14 -0500 (EST), snipped-for-privacy@grex.org (Graven Water) wrote:

Yes, overbend since it will spring back. Use trial and error if you have the time.
Laura, steaming the wood might save you a lot of headaches.
Alternatively, look into laminating the backs yourself if you have a bunch to do. Build jigs and clamp them to make the proper curve, then finish cutting to size.
-- You can either hold yourself up to the unrealistic standards of others, or ignore them and concentrate on being happy with yourself as you are. -- Jeph Jacques
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On 12/27/2012 4:35 PM, Graven Water wrote:

Water is needed when heating wood to avoid scorching the wood. I assume you are planing on gluing up a bunch of 1/8" oak veneer then clamping it in a mold until the glue dries. You should not need to wet anything other than with glue.

If steam bending you would, don't think so with gluing up thin strips. Steam bending you need to heat the wood to at least to 200 degrees to soften the cells so they can bend. The steam aids in transferring heat w/o burning/scorching the wood. Oak is pretty flexible in 1/8" strips so you should have no trouble just gluing/clamping a bunch in a mold .
Try to get straight grain with little or no run out, although I wouldn't worry about that much with thin strips and just a small bend as you are doing.
To permanently bend 1/8" strips alone, you could just heat it up with a heat gun and bend over a curved pipe or something. In that case, you might want to soak the wood first to prevent scorching.
--
Jack
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