Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on June 07, 2017, 10:53:18 am
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I've been doing a lot of reading about bending wood. All the steam bending info says that we put a strap on the wood to keep the outside of the curve from stretching. They say that wood won't stretch much so we need to concentrate on compressing the inside of the bend. Now, think dry heat bending. Most dry heat bending is used to put in reflex or recurves. We clamp the limb to a caul and heat the belly. Notice that we are doing exactly the opposite of what the steam benders are saying. We are heating the outside of the bend and taking care not to heat the inside. With the cold inside curve not being able to compress don't we have to be stretching the outside(the belly)?
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Whoever says wood doesn't stretch much has never recurved a yew bow!
Don I think you are over thinking this, everyone's heat bendin opinions are formed
off their own experiences. I've never used a metal strap, I boil or steam sharp curves,
and use dry heat for small corrections and bends. With dry heat or wet heat, the belly is
always stretching, and the back of the curve is always compressing, how else would the bend happen?
I wouldn't call the inside curve cold, it's still getting heated.
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For reflexing, deflexing and straightening you shouldn't need support on the tension side(outside of the curve) of the bend because the bends usually aren't that drastic. On recurves, where the bend is more drastic support is needed in the way of a metal band to keep the tension side from lifting splinters or from cracking.The metal band is attached to to the limb and the form so it tightens against the tension side as you bend the recurve.
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I over think everything, it's part of my makeup ;D ;D ;D Blame my parents
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I have always heated all sides during a dry heat bend... done it hundreds of times. What's it supposed to hurt?
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Possibly overheating the back and making it brittle.
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Oh, ok. I never had anything bad like that happen. Apparently I'm not heating it too much then. :)
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What happens when wood is heated up to around 400 degrees F is that the cells plasticize and then the wood can be re-shaped and that is what we do when heat-treating/reflexing
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I don't think it really doesn't take much more than 200 deg F to do the job on most woods with steam and about 340 deg F with dry heat.......
DBar
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I over think everything, it's part of my makeup ;D ;D ;D Blame my parents
My wife allus says "your parents can screw up your childhood, but it's up to you to screw up your adulthood". She's wise, but I'm glad she doesn't look over my shoulder while I'm working on a bow! :BB
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Perhaps this will interest someone; years ago I lived on the Chesapeake Bay and there was a very well known furniture maker that I met and befriended. We hung out a lot and I remember him talking about using a strap to achieve really tight bends.
The idea is the strap replaces the tension and puts the whole piece of wood under compression, allowing some pretty ridiculous bends. It works if you have stops on the strap. I made one for bows with adjustable stops and it works. Only experimented. Anyway whether it's there to hold down splinters or to take all of the tension they work. Thats it, that's all I got. :)