Bening side blanket heat?

My mold is made to the dimensions I want the ukulele to be.
My mahogany sides are sanded down to 080".

My sides spring back when the clamps come off some. I am not sure what's acceptable. I made a body mold, so I know that once the top and bottom are glued on that will solve some of the problems, but I am guessing that's not the way it should be done. If done correctly do the sides hold there shape?

I am wondering if I am not getting the sides hot enough or if I am not leaving them up to temperature long enough.

I have an infrared temperature gun that indicates it is getting up to nearly 300º. Once it gets up to that temperature, I turn down the heat.

I leave it clamped for 24 hours.

The sandwich:
I start with some Home Depot aluminum flashing, then very wet brown paper, the dampened side, more wet paper the heating blanket, and topped off with more aluminum flashing.

I am not using tinfoil. I have heard it's used to protect the wood if you are using Spring Steel, which I am not using.

Any suggestions would be much appreciated.

Thank you

For me at least, some springback is inevitable on my bent sides. I just horse them into the mold and glue up. However, there is springback and then there is SPRINGBACK! It would seem to me that 80 is a bit thick for bending. I aim for < 70. A couple of things you can try:

- Make your sides thinner.

- After your sides are bent and on the mold wait until they completely cool and sit awhile (over night) and then wet and heat them up to bending temperature again and leave them on the mold another 24 hours. This will help but will not completely prevent springback.

- Make a bending form that has tighter radiuses so that the side springback to the desired curve.

You can make bending forms with a little more curve to account for spring back. Also you can touch up the bend on your bending iron. Letting the bend cool then running back up to 275F or so a time or two also helps.

Make a bending form that has tighter radiuses so that the side springback to the desired curve.

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Sequioa makes a great points here.....
One should also consider any part of the sandwich that is between the wood being bent and your form as well as this changes things in some cases.....thin metal slats not so much but added together with a heating blanket etc. it can add up.....

But with all that said if the springback isn't huge you probably have no worries

You can get cheap orphaned sides and such at places like RC tonewoods to practice on if you really want to dial it in without risking the good stuff

Just keep at it and you will get it dialed

Steve-atl said:

I have an infrared temperature gun that indicates it is getting up to nearly 300º. Once it gets up to that temperature, I turn down the heat.


Thank you

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Oh, one more thing: Resist the temptation to get the temperature really hot (like 300 degrees). What this tends to do is boil off your moisture and you end up drying out and cooking your wood. Dry, cooked wood tends to not bend well. It is the steam and not the heat that causes wood to bend. Keep your temps around the boiling point of water or just a little higher (220 degrees). I bend by hand and don't pay any attention to temperature: When the wood starts to bend I bend it. It is a feel kinda of thing that you feel through your hands. I sometimes think that people try to rely on bending forms and temperature gauges too much. When wood wants to bend it gets a weird kinda of floppy feel you can feel with your hands (gloved of coarse) and then it bends.