Primitive Archer
Main Discussion Area => Bows => Topic started by: radius on May 13, 2008, 09:46:27 pm
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I have almost completed a pyramid shaped reflexed bow of osage backed with hickory. The limbs are lenticular, my first try at that. Looks good, feels good.
PROBLEM: HINGE: it's not a huge hinge, but it's there, and is the result of too little practice with a too-sharp scraper. I wonder if I heat-treat that spot, would it temper out the hinge?
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I've had limited sucess doing that. I had a bow with a weak limb, and toasted the heck out of it and then burnished. The weight came up by two pounds and the limb stayed where I wanted it too. All you can do is try. The worst that can happen is it will break sooner than later.
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anyone else?
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I would remove material from either side of the hinge area to get the limb bending evenly and then reflex and heat treat the whole limb to gain some strength on that side.
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of course ... too late for that now...it's a mild hinge, let's say an over-enthusiastic bend...and i just tillered the other limb to meet it or so, and then sanded it clear...
but in the future....!
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I've had some temporary success with heat-treating a weak spot. But it usually comes back over-time.
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when u are using the C clamps and block method in gluing up your form, sometimes when your pre-tiller lams are not "spot on" they will tend to bend unevently when u clamp them up.
I have had much success in "heat tiller" u will need experience to tell u how much to heat as too much heat will cause the glue to delam (i use smooth on) heat a little and force bend that area that is not bending enough.
Most important , do it little be little and take your time, cheers Robin
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I have seen a thin patch applied on the belly at the hinge work. That along with heat treating and removing the stress on the hinge by removing material on each side and the other limb as Ryan said. Sometimes I think a combination of "fixes" might be the ticket...nothing ventured, nothing gained. :)
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Hi All
I have read in the TBB 4 that a thin layer of raw flax can be used to correct a weak spot in a limb. I have just got some to do a repair, but as yet have not tried it! Would interested to know if it works?
Peter (UK)
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Depending on how severe, a hinge is where he cells has collapsed due to over stressing. No matter how much heat treating you do the cells in that area are still damaged. An overlay of some kind or replacing the damaged wood with an inlay would be the most effective method. You might get a quick fix with heat treating but I would imagine it would be temporary. I haven't tried it but I don't think I could trust a hinge that was just heat treated. If the h9inge is just beginning, Ryano's method would be your best bet. Pat
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It's worked for me, but only on flatbows. Haven't got it to work on narrower flatbows.
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The heat needed to temper the belly will damage the glue
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thanks, it's just yellow glue, too
i am just going to live with it, and chalk it up to experience...
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ok!
'nother hinge!
This one is bamboo backed maple, the bow is 60" long in total, and came in underweight at about 42# at 28". When I first drew it to 28, it developed a hinge which was not present before.
I am going to heat treat the whole belly, both limbs, but concentrate especially on the hinge.
Question:
When I sand out the "char" won't the benefits of heating the bow be lost?
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I usually become unhinged when I see that frightful hinge. Those inevitable chrysals just ruin that stave for me. There are fixes But...The best way to fix a hinge it to not get one. Avoid power tools when tillering until you've made 2 dozen bows. Take long strokes with your wood removal tool often going beyond the target area by a little bit and when possible remove wood from the whole length of the limb in one pass. No, I would not use heat. I would remove wood from either side of the hinge and retiller the other limb too. I would not add any more stress to that limb by reflexing or recurving. I would add some rawhide or 1/8 inch thick birch bark to the belly over the hinge. This is what I would and would not do. Have and have not done. :) Jawge
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I would remove material from either side of the hinge area to get the limb bending evenly and then reflex and heat treat the whole limb to gain some strength on that side.
We've been over this .....The glue will delaminate from the heat most likely.
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you're right we have...
and you're right,....it did :(
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Often times restraint is our best tool. We learn from our mistakes, pick up another stave and go on. If you leaned something, radius, you should remove the frowny face and replace it with a smiley face. There's still time to edit that lost post. Come on you can do it. :) Jawge
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Thanks Jawge...
It was a weird hinge...showed no sign at all,the bow was bending fine...in fact, the hinge came up on what was at first the stiffer limb! Everything was cool, i had it bending, gradually increased the brace height like i always do...got it up to 6" or so, weighed it with the tillering stick on the scale...and creak! hinge...!
ah well... ;D
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radius, proud of ya. :) I mean its not like I ever had a hinge or chrysals form on a bow. LOL. I can remember at least 6. Probably had 4 times that. I've played seesaw tiller too. Fix one limb. The other limb goes off more. Back and forth. Frustrating! Did you say tillering stick? Hmm. :) Jawge
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yeah, my setup is pretty hokey, and right now i'm staying at a friend's place. Next month i'm moving to a place with a shop, and I'll set up a tillering tree there, with a pulley and everything...i'm still trying to catchup to you old pros...coming soon to a tillering tree near you! ::) :P
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I am old but not a pro bowyer. I am a hobbyist, an amateur. There you go. Rope and pulley is the way to go. I almost became unhinged when you said you were using one of those infernal contraptions. :) Jawge
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Jawge, do you remember a couple years ago a stranger who bothered you with a whole bunch of questions about bow making? That was me...you were like, "Congratulations, you got a bow." I had the distinct impression that you were also saying, "Quit bothering me." Maybe you weren't, but i thought you MUST be!
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You must be confusing me with someone else, radius. You can ask me questions anytime you want. Now I did make my living answering chem questions. But I'm retired now. So you can ask bow questions but no chem questions. The only "moles" I deal with now are in my lawn. Night. :) Jawge
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no it was you...you may forget, but i don't...i used your website at verizon.net over and over again, and emailed you several times...ah well...night
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radius, you are probably correct. I get a lot of emails and questions. Sorry if yI gave you the impression I was uninterested. Ask away. :) Jawge