Primitive Archer
Main Discussion Area => Bows => Topic started by: Jon Kaw on August 26, 2015, 08:45:26 pm
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Hey guys, I wanted to get your expert guidance.
I was using dry heat to get some twist out of the limb of an Osage bow I'm working on. I had just gotten everything clamped in place and was considering heating the other limb to see if I could get some more back set when I heard a loud POP. Upon inspection I found that the riser had cracked about an inch down the fadeout.
(http://i.imgur.com/xDWMKWP.jpg)
It's not a big crack but does go all the way through the riser. This picture was taken while the bow was still clamped, after I removed the clamps the crack closed up but is still noticeable. So my question is what is the best way to deal with this? Should I just glue it back together, or wrap the crack with another material, or cut the handle, glue another piece of wood on and make a laminated handle? Or should I do something else entirely? Or did I just make firewood? ??? On the bright side I did get the twist out of the limb. :P
Also I noticed a crack on the edge of the back of the bow, on the limb I wasn't untwisting.
(http://i.imgur.com/kXobLKz.jpg)
Do I need to back this bow? I think I can narrow the limb a bit and eliminate the crack if I need to. Is there a better way to deal with this?
Thanks in advance, I humbly await your advice, opinions and criticisms.
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Should be fine if you fill the crack with epoxy. Maybe a tight wrapping around it as well.
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You could honestly pretend nothing happened to the handle. On the limb, narrow it down until the crack is out or thin locktite professional super glue and a clamp works well.
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The crack in the handle won't give yu any problems, I would just open it up and flow some glue into it and clamp it. On the limb crack I would just narrow the limb a bit. Are you following the grain on those limbs, the grain seems to be wavy and the limb looks straight?
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Thanks guys, seems like it's not as bad as I feared. Badger, I'm doing my best to follow the grain, the limb edges are definitely not straight. Thanks again.
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Hard to tell, but if that is the back, I also looks like you are not down to a single ring. Do you have a violation?
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I did my best to get it down to a single ring, I don't think it's violated. There is still some spring growth on the back that I planned to sand away.
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Whenever I have a crack during building I just start squirting thin CA glue in there and gently clamp it together. I will typically keep adding glue as I reduce it down if any part of the crack is unfilled.
You may see pictures of bows with significant cracks filled with CA glue. Typically works out.
The handle is less concern than the limb. Start adding glue early and keep adding it until you have a finished limb and a filled crack.
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Jon, get yourself a scraper and round the corners on it for cleaning up your back. A regulad cabinet scraper runs about 6.00 and you keep them sharp with a file. Just file straight across at 90 degrees. I never bother to push a burr but many do so.
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When was that stave cut? Is it holding excess moisture? That will make them check easier when heat bending.
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The stave was cut spring of '13. When I got it the bark was off with the back and belly sealed. There were no obvious checks in the back. I got it last fall and it has been stored inside my shop ever since. Thanks again for everyone's help.
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That section was too thick for dry heat. Dry heat works best when the limbs are floor tillered, so relatively think. Steaming would be better if you need to bend the handle section for a setback.
Also do you use oil with dry heat? It seems to stop cracking with osage.
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You see that happen a lot when adding reflex, especially if there is a hump on the back around the handle, I just fill with super glue/clamp and move on. It is on the compression side anyway and pulling it together when you draw so shouldn't be a problem. :)
Pappy
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To be clear I wasn't trying to bend the fade or handle, the clamp was at least 5" down the limb. I probably should of been using oil with the dry heat, I'm new to this and it's all a big experiment, so point taken and lesson learned.
There is a hump in the limb about 3" from the fade. I'll be gluing the crack and moving forward.
I had it pretty well floor tillered so after letting it rest a few days I'll start with the tillering string.
You guys are the best, thanks again.
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I have done this more than I like to admit . What everyone else has said. In the future don't try to get it all in one go. I am always trying to get the grain as straight as possible. Also bending the wood where I think it needs to be for me. Sometimes it is just not ment to be. The more you heat and straighten wood the better you will get. I prefer dry heat but steam may get you more response from the wood. When you do this expect some failures. At least I have had a bunch. But when you get one where you want it and your bow design was good . Ye haw now you have a shooter. Arvin
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I use a cawl sometimes and as pappy said a hump in the back will cause this nearly every time. So i cut my cawl in half and do one limb at at time. If I have a big hump in the handle i wedge the handle and clamp it to my bench. 21/4 under handle 13/4 under mid limb 11/4 7-9" from end. Blocking and clamping as I go from fade to tip. I spend hours on that bench heating bows. Then there is that rascle
Blackhawk that builds a bow out of a Boomerang in four hours. Not putting any heat on it. Lol Arvin
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If I have a hump or lump in the back of a bow I cut a"V" notch in the caul to accommodate it when it bends. If I get too many notches in my caul I use 5 min epoxy to glue a chunk in the notch. Rasp it smooth and I'm ready for the next one. It's one of the only times I use 5 min epoxy.
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Thanks guys, seems like it's not as bad as I feared. Badger, I'm doing my best to follow the grain, the limb edges are definitely not straight. Thanks again.
This isa coorrect. It cracked because you were cranking it foreward with the heat and doing the twist removal. Under the opposite forces, the crack would close up, and since that's the way the bow bends, it's fine. Also if you look, the amount of wood thickness from back to crack in the bow is still a good bit thicker than the limbs.
I would clamp it so the crack opens, get some quality glue in the, probablu epoxy, and then unclamp it, and clamp the crack shut.
You could shave a tiny sliver of wood and glue it in for a shim (have done myself) but since the cracked surface is uneven, I wouldn't bother. If it was bigger or worse, I might saw in a kerf to square it up and glue in a splint, but really, why bother?