Primitive Archer
Main Discussion Area => Bows => Topic started by: Key on May 19, 2008, 12:09:26 pm
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I just got a long string on a hickory selfbow I am making. I have heard about heat tempering the belly on a bow but I have never done it. I would like some advise please. How much heat for how long? Will a heat gun work? Should I do this before or after the final tiller?
Thanks in advance.
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I usually do it when I have it out to about 20 or so inches.I just heat it till the wood starts to change color and yes I use a heat gun.I ant sure I do it like Marc tell us to or like anyone else but it dose work and will really help the bow. :)
Pappy
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TBB 4 has a great chapter about it, after reading it I made some adjustments on how I do it !
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Lately I've been using a hardwood fire for tempering. Works well and saves on hydro :).
I almost always temper after floor tillering
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I wait until the bow is fully tillered. The tempering increases the draw weight (a good thing)...and I either leave it as-is or make minor tillering adjustments (with sandpaper) if one of the limbs is not bending evenly with the other. So far, the heat tempering I've done increases the draw weight by about 5#. I use a heat gun on the highest setting and hold it about 4" away. I don't hold it in one spot for too long....usually moving the gun back and forth along a 6" area of the bow. Some spots (and bows) will temper faster than others so I start slow and get more aggressive when I get a "feel" for the wood.
Also, with hickory, I've noticed that tempering the back (a little) doesn't hurt. ;D
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Thanks for the input everyone. I am going to temper the back a little also.
Next question is can I add a little more "back set" at the same time and how long should I hold that back set before I release it from the form? Sorry I didn't ask this question in the first post.
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By backset, I'm guessing you mean reflex. You should always put a little bit in when heating, even if it's just a little. I've done both striaght and slightly reflexed (about 1" or so) and reflex seems to make it easier. Dunno exactly why, but it does. After you heat treated the belly, let it sit until tit cools off before you take it out. Overnight before further tillering (let the "inside" cool off too).
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Marc said in his chapter, and ive hade the experience, you loose about 50% of the induced reflex after you take it out of the form. so plan accordingly. i just did some heat treating on the inner limbs of a hickroy bow that turned out to bendy near the handle. im waiting for it to re-hydrate till i try it out. if you make a jig that holds the heat gun (like in Marcs chapter) it makes it alot easier. plus while your heat treating, you can be scrapping on another bow!
Phil
If you all cant tell, just read Marc's chapter the other night...good stuff Marc!
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Ok I am ready to give it a try now. Thanks everyone
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Don't do the back !!!!!!!! just the belly.
Pappy
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again, DON"T DO THE BACK!!! JUST THE BELLY!!! You will weaken the tensile strength of the back by heat treating it. Pat
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Ok Pat, I will not temper the back. The attached picture is on the long string at 10 inches. The bow is 72 inches long and I am making it for a friend who has a 30 inch draw. He wants it to end up at 60 pounds. I have never made a selfbow that could be drawn to 30 inches, that is why I am making the bow so long and wanted to temper the belly. I will let you guys know how it comes out.
Again, thanks for all the advice.
If I have the time I am going to temper it today.
[attachment deleted by admin]
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I don't know if this will help but I'm working on one now so I'll throw it out there. I got this osage to 55# @ 25". Target is 55# @ 27" so I stopped and heated the belly on Pappy's form which puts in reflex. I then recurved the tips but afterwards could not even string it. Unlike my last bow it held almost all of the bend. I tillered more and finally got it strung but the string lay on the recurve like an actual recurve instead of a longbow and it wanted to twist. In fact the sting popped off by twisting so I'm stopping until I can get an assessment from the Professors (Pappy and GregB). It must have picked up 10+ lbs. I'm concerned with how to take the twist out so I'm over my head and won't go further without adult supervision. Here are a couple of photos.
(http://i289.photobucket.com/albums/ll210/RangerB/TN%20Classic/knot2.jpg)
(http://i289.photobucket.com/albums/ll210/RangerB/TN%20Classic/knot1.jpg)
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Looking good,we can get it straightened out,I will be gone this weekend but Greg may be around
to give you a hand,just don't get carried away and do something you may be sorry for,O course I know you wouldn't do that Ranger ;D.Didn't mean to hijack your thread just need to respond to Ranger.By the way yours is looking good also. Be careful everytime I try and make them longer than I am use to I have trouble hitting weight,just have to go slow and easy. :)
Pappy
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Hey all. I'm currently working on a hickory backed/ hickory board bow glued up with TB3. It's 64" NTN and I'm shooting for 50# at 28". Do you think if I heat treat this on the belly would that mess with my glue joint. I have roughed in the bow but am letting it dry out a bit more before floor tillering cuz my test piece seemed a bit green even though the lumber was kiln dried.
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If it is already glued up the heat treating will cause the glue to release. To heat treat a backed bow you would have to pre-tiller the belly, heat treat it then do your glue up.
Also, hickory is hygroscopic, meaning it picks up and releases moisture quite readily. By using a water based glue, you have added more moisture to the wood. If you have a hot box you can speed up the drying process. Pat
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Sorry about the advice on heat tempering the back of your hickory bow. Pat B and Pappy have lots more experience than I have.
I've made a short hickory bow with a lot of heat-induced reflex in the handle. The reflex was "pulling out" during tillering until I hit the back of the handle with the heat gun. Of course, I didn't heat it as much as the belly. It made a significant difference. The handle is "bendy" and I haven't seen any cracks or heard any "snapping" sounds from the handle after about 200 shots. It might just be a fluke? It might be that my piece hickory is so strong that the weakening hasn't affected the bow? I dunno....but I'd play it safe and listen to the guys with experience. ;D
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Patrick, sounds like you probably didn't heat treat it, just lowered the moisture content. Heat treating the back is dangerous at best. Justin