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Bending for Flattening

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Forum topic by James posted 07-24-2013 05:43 PM 1290 views 0 times favorited 17 replies Add to Favorites Watch
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James

102 posts in 1250 days


07-24-2013 05:43 PM

I’m in the process of planning to make a ukulele. I got some 1/8” walnut which is beautifully bookmatched and I need to glue it up. Problem is the boards are slightly warped/bowed. How would I go about making them flat again without taking wood off? They’re 6”x16”x1/8”.

-- James - Semper Fi


17 replies so far

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mahdee

3551 posts in 1230 days


#1 posted 07-24-2013 06:31 PM

Don’t worry about them bending due to humidity. Once you glue in the braces to it, it will straighten up. You can also introduce some steam to the bords, lay them down on a flat board and put a flat board on top then put in the overn to dry.

-- earthartandfoods.com

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James

102 posts in 1250 days


#2 posted 07-24-2013 06:35 PM

The issue I’m having is that they are warped enough that jointing/gluing will be difficult. I’d like to get them flatter before I joint them.

-- James - Semper Fi

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mahdee

3551 posts in 1230 days


#3 posted 07-24-2013 06:58 PM

Then the oven process is your best choice. Be sure the heat is gradual and not exceed 120 or so.

-- earthartandfoods.com

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mahdee

3551 posts in 1230 days


#4 posted 07-24-2013 07:00 PM

One more tip I can think of: sandwich both boards seperately between two boards and clamp lightly so that only 1/8 of the edge to be glued is exposed.

-- earthartandfoods.com

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Nomad62

726 posts in 2421 days


#5 posted 07-24-2013 07:14 PM

A high-end bow maker (violins, etc) showed me at a show that you can use a Sterno (or similar) can and heat the wood to just before scorching, then hold/clamp it in place as it cools; it will stay there. Obviously some practice would be advised.

-- Power tools put us ahead of the monkeys

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James

102 posts in 1250 days


#6 posted 07-24-2013 07:15 PM

The issue I’m having is that they are warped enough that jointing/gluing will be difficult. I’d like to get them flatter before I joint them.

-- James - Semper Fi

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James

102 posts in 1250 days


#7 posted 07-24-2013 07:17 PM

How would I heat wood to just below scorching???

-- James - Semper Fi

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James

102 posts in 1250 days


#8 posted 07-24-2013 07:21 PM

I’m gonna make a jig like a tennis raquet and try the oven thing. How much steam do I need prior? Will a Vicks machine do the trick?

-- James - Semper Fi

View Loren's profile

Loren

8302 posts in 3111 days


#9 posted 07-24-2013 07:32 PM

Clamp them together in a vise and shoot the joints
together with a hand plane.

Use cauls to flatten the plates in glue up. Wedges
and rope over a backing board is an old luthier trick.

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James

102 posts in 1250 days


#10 posted 07-24-2013 08:28 PM

Explain the wedges and ropes…

-- James - Semper Fi

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James

102 posts in 1250 days


#11 posted 07-25-2013 09:32 PM

Loren…?

-- James - Semper Fi

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coolerjack

20 posts in 1645 days


#12 posted 07-25-2013 09:41 PM

A recent post by a fellow lumberjock on rope wedge clamps

http://lumberjocks.com/projects/86796.

View James's profile

James

102 posts in 1250 days


#13 posted 07-29-2013 07:06 PM

I did the planing and glue-up yesterday. There’s a slight bow in the center (might not be a “bow”) where the wood wants to bend up like a book. It’s not bad – maybe a cm or so – so once I put it into the project, it’ll be glued in place. I used the rectangle bar clamps with c-clamps on the sides to keep the wood even.

-- James - Semper Fi

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Earlextech

1159 posts in 2153 days


#14 posted 07-29-2013 07:20 PM

Every time I’m out showing our Steam Generator, along with some bent wood to show what can be done, someone makes the joke that the wood they bought was already bent or twisted that way and can they use our generator to help straighten them. Yes you can and it’s safer than even a sterno can or using the oven.
Using 1/8” boards I would only steam them 10-15 minutes and then clamp them flat between two boards until they dry.

-- Sam Hamory - The project is never finished until its "Finished"!

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James

102 posts in 1250 days


#15 posted 07-29-2013 07:25 PM

How do they dry clamped inside another board. That’s like throwing a pair of balled up socks in the washer and waiting for the dryer to dry them. It’d take 10 dryer cycles but if they weren’t balled up, it would only take 20 minutes.

-- James - Semper Fi

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