Primitive Archer
Main Discussion Area => Bows => Topic started by: IrishJay on November 22, 2019, 11:34:42 am
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In light of some recent discussion on here about heat treating, specifically depth of penetration, I came to to the conclusion that I've been working with the heat gun too close to the wood. This makes the surface brown up quickly, but doesn't give the heat time to penetrate much.
I spent about 20 min on the toasted part of this limb with the gun further away. As a result I was able to feel heat all the way through to the back.
Does it look dark enough? Or should I go over it again?
(https://i.imgur.com/Ij2Pu7Z.jpg)
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If anything, I would say it is too dark. I do not try to scorch the belly of a bow by heat treating it. My goal is to get the limb hot and keep it that way for 10-20 minutes. The surface does darken, but not that much and the color change is an outcome of heat treating, not a goal in itself.
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It looks about right. That said it varies from species to species and from tree to tree. I just did that Yew and I had it up to 450°f and it hardly browned at all. You should hold the gun about 3 1/2-4" from the wood.
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I do the same as Eric, I keep my gun very close but also keep it moving. I never scorch the limb, it only gets slightly darker.
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Ended up spending over an hour on one limb. I think I got as much penetration as possible, belly ended up a fairly even chocolate brown.
(https://i.imgur.com/EglPXNv.jpg)
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I should add that I learned my technique from Steve (Badger). I set my caul up so that there are places where I can touch the back of the bow, and heat the limb until the back is hot, not just the belly. I then keep heating to keep the back hot for 10-20 minutes. I spend 30-40 minutes on each limb. I keep the heat gun fairly close to the limb, maybe a couple inches away.
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Did you use a form? The limb looks like it's going two different ways.
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Pat, limb has a curve in it but the tips align nicely. String lines up well on the handle and nothing twists when its drawn.
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Heres the back of that same limb, i think the other camera angle exaggerated the curve in it.
(https://i.imgur.com/xuxGX8r.jpg)
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Is that elm?heat treating areas that don't bend ,unless stiffening reasons is a waste in my opinion.
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I think its hickory. Also the whole bow bends. The handle doesn't bend much but it does bend.
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Im pretty sure it's elm and it shouldn't bend through the handle judging by your design.
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Jay,did you have it tillered before heat treating?
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Yeah it was tillered to 46#@28". Depending how much weight it gains from heat treat I may have to make a few more scrapes to bring it back down a little. Its for my dad and he likes to stay <50#.
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Well judging by your heat treating I would guess it's closer to 60 now.
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Bush, pretty sure its not elm just based on its hardness. Its the wood from page 2 & 3 of this thread. http://www.primitivearcher.com/smf/index.php/topic,66772.msg938725.html#msg938725
It's a 60" plains gullwing so its definitely supposed to bend through the hand.
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The interlocking grain at the top of the photo really looks like elm.the shelf on the Gullwing threw me off.my bad.
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To add to this, it is really species specific in my opinion. Most of my bows over the decades have been Osage. It was initially argued that Osage didn't benefit much from tempering, but I have found that in my experience it most certainly does. I get it dark and it doesn't go very deep. Seems to work. Not so with Elm. Long and slow is called for.
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2x