Primitive Archer
Main Discussion Area => Bows => Topic started by: PEARL DRUMS on November 09, 2011, 09:33:48 am
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I need a new rig to hold my heat gun for heat treating bellies. Anybody want to give away their secrets? I am using an old desk lamp base and clamp. It works okay, but Im sure there are better holding devices.
Thanks all
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The way i was tought was just to hold it in my hand nothing has ever gone wrong with that.
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I've heat treated quite a bit. I definitely think it's better to hold it and heat it. I would clamp the bow when I first started and because your "toasting" one small section at a time I think there is liability that the wood can actually bend in a way you may want if you temper an area longer than another. Guess what I'm trying to say is, if your just tempering to compress belly cells to avoid set, there's no need for a rig, it only complicates it.
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Certain whitewoods seem to take a longggggg time to start to temper and my tennis elbow cant take holding my heatgun that long anymore, hence the "holder" I need to come up with. I always temper over a 3" reflex form so I dont need to worry much about the limbs moving on me.
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Rough pic but you get the idea.
(http://i1108.photobucket.com/albums/h418/EarlLane/013.jpg)
Lane
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here's my okie rig, just taped to a dolly, work's good(http://i623.photobucket.com/albums/tt320/bubncheryl/blade002-15.jpg)
I think Mark St Louis shows a nice one in the archives on heat treating, Bub
actually to the left on the horse is a stand for one, just have to drill a hole for the gun to sit in
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BC Grover on YOUTUBE uses one on his walnut bow build to straighten a limb, looks pretty easy to build too. A couple pieces of 2x6 or 2x12 and a piece of 3/4 inch ply wood for the top and a few screws should be all you need. Heck, I could build it for ya if you wanted. I have all the materials required to make it. I would just need to know what the diameter is on the heat gun you have so I can cut the hole in the top.
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Marc's seems to be pretty simple and easy to whip up. I tempered one limb last night with my "old" rig and will try a new one tonite to finish off the other limb. Thanks fo the offer Ryan, I have all kinds of stuff around to build one though!
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Here is the rig that I use - inspired by Mark St Louis.
(http://i793.photobucket.com/albums/yy217/gferlitsch/Bow%20Making/DryHeatSetup.jpg)
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That's the one
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I like the looks of that rig Gordon. And I willing to bet that the sides direct the heat downward more so than my desk lamp and clamp rig does.
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A question about "Tempering" judging from the last photo it looks like tempering refers to dry heat bending the wood on a form and then letting it cool to set it, instead of steam bending the wood and letting it cool and dry on a form.
Is there more to it that this?
I've built furniture and boats and steam bent or cold laminated a lot of wood, but never tried the heat gun thing. Am I understanding this? I guess it is possible due to the relatively thin dimension of the wood. Has anyone tried this with green wood and or with a propane torch?
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Mine is like Gordon's, inspired by Mark's article "High Performance Selfbow" in the magazine a few years ago.
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Foot
what you describe is dry heat bending!
Temporing is referring to drying out the wood to the point that the cells begin to calapse so it is stiffer and harder !
which takes a higher temperature ,or longer time than just warming it up enough to bend !
Hope that helps !!
Guy
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Foot,
The setup in the picture does both, it allows me to bend the limb to a form using dry heat and temper the wood at the same time.
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The high heat of a heat gun plasticizes the wood and allows it to be reshaped into a different form. It also seems to harden the wood, possibly through a change in its density by driving the air in the cells out. Steam actually seems to weaken wood a bit.
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If you were to try dry heat bending or heat tempering green wood it would check and crack on you so bad as to probably ruin any chances of getting a bow from it.
Dry wood, dry heat.
Wet wood, wet heat.
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Words to live by, jw ;)
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J-dub is right on. Green wood will often open big crevices up. I have had it happen over night while it cooled on the form, even though it was perfect when I shut the shop lights off the day before. The piece I am working now is bone dry white ash.
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If you have a chace, check out Marc St Louis' article in TB Vol4 on heat treating. It covers everything.