Primitive Archer
Main Discussion Area => Bows => Topic started by: grinner on July 27, 2012, 04:24:48 pm
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HI, i am working on tillering a hackberry bow and it has formed 3 horizontal crack acrosss the limbs. They are very shallow what could be causeing thisand how can i fix it thanks
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You don't give enough information for a proper answer. Where are these cracks? Pictures would be a big help. If they're on the belly, it sounds like chrysals, which are compression fractures. These are usually caused by one area of the limb doing more than its share of the work. In this case, the chrysals would all be in one small area of the limb. If they're spread over the whole limb, it probably means the design is wrong for that particular wood.
You might be able to fix it by removing the crushed wood and glueing a slat of new wood onto the belly and then retillering. I think when others chime in, they'll mostly tell you to start another bow. I have repaired a couple bows this way, and it worked, but doesn't look very nice.
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sorry i forgot to say that they where on the back of the bow but they are to small to take a picture of.
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If they were on the belly I'd say they were compression chrysals. Across the back, they are either scratches or the bow failed there. Is it bending real hard right at the cracks? Do you have a hinge there?
You don't really fix cracks. I suppose you might put a layer of sinew over the bow but I wouldn't waste sinew on a broken bow.
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How did those cracks just "form"? They don't come out of nowhere. Did it happen in the tiller process? And where are they located, how far out from the handle? Did you damage the grain on the back?
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Mid limb and they are straight across the almost look like they could just be the polyurethane cracking where i seal the back. DOes some kinds of polyurethane crack when bent?
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I have had a thin growth ring fail in the back of q bow before. Brace the bow and draw it a little and see if the crack opens up. Careful it doesn't go pop in your face. Never had polly varnish crack before.
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Some poly could crack I suppose, but not in July Im thinking. Sounds like a tension shear on an over stressed or poorly tillered bow.
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Those are drying cracks your stavewas'nt completely dry. And there where moisture escaped faster than the rest of the bow.
SUPER GLUE the cracks and any others that might show up. Either put it in a hot box until you get the right moisture content or in a car window or in the sun for a few weeks. But don't let it get wet of due'd on in the mornings. Hackberries a white wood and seasons pretty fast and it sounds like your stave is just about seasoned enough.
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I checked it with a moister meter and it was at 8 percent. So i dont think it was from the but the cracks are deffenatly into the wood