Primitive Archer
Main Discussion Area => Bows => Topic started by: jayman448 on March 01, 2015, 11:38:52 pm
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So i was thinking (never a good thing xD) birch has a tendency to get compression fractures. If a guy was to tiller up a bow and it developed compression fractures, would laminating a 3mm thick strip of say, maple save the bow from Belly compressions and ultimate failure?
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I've used osage and ipe as add on belly lams with good results. If your bow is birch, maple might be a good option but that is just a guess.
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Maybe and maybe not pending on how deep they go...I've seen them go all the way to the backing strip before
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Even the name brand Band-Aids loose their adhesion after a while!
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So i was thinking (never a good thing xD) birch has a tendency to get compression fractures. If a guy was to tiller up a bow and it developed compression fractures, would laminating a 3mm thick strip of say, maple save the bow from Belly compressions and ultimate failure?
So... have you tillered up a birch bow which developed compression fractures?
Maple is another tension strong wood, and excels more as a backing wood. My favourite, actually. Try using a more compression strong wood on the belly. Any of the standards... ipe, osage, yew heartwood, etc.
All you're really doing is trying to patch a critical mistake. Birch will make a bow if you design and tiller it carefully. If you don't, learn from your mistake and endeavour to not repeat it. I've learned far more from mistakes than successes.
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A friend of mine sucsessfuly patched a chrysaled bow limb. The chrysals where in one week spot. He sanded thay spot and glued on a thin lamination and once the glue dried he sanded it smooth and adjusted the tiller. I never tried it but he ssid it hold.
I wonder what the experts here have to say about this fix....
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It will hold, but for how long? The truth of the matter is underneath that ultra thin laminate is a hornets nest held together by glue. Eventually after repeated shots that chrysal will expand to the back causing an explosion. It doesn't matter that the tiller is corrected after the lam is added. That limb is like a spring and after repeated bending back and forth those chrysals will grow, they have to.
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A friend of mine sucsessfuly patched a chrysaled bow limb. The chrysals where in one week spot. He sanded thay spot and glued on a thin lamination and once the glue dried he sanded it smooth and adjusted the tiller. I never tried it but he ssid it hold.
I wonder what the experts here have to say about this fix....
well yes.. very shallow in one concentrated spot. ( this bow is still the one i spoke of a while ago that was given up on by a guy i know. ive been trying to save it XD. also at very worst i figure its a good learning experience eh?)
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A friend of mine sucsessfuly patched a chrysaled bow limb. The chrysals where in one week spot. He sanded thay spot and glued on a thin lamination and once the glue dried he sanded it smooth and adjusted the tiller. I never tried it but he ssid it hold.
I wonder what the experts here have to say about this fix....
i dont have access to any of those woods. (im quite north of your uppermost boarder) what about something like hickory or walnut?
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It will hold, but for how long? The truth of the matter is underneath that ultra thin laminate is a hornets nest held together by glue. Eventually after repeated shots that chrysal will expand to the back causing an explosion. It doesn't matter that the tiller is corrected after the lam is added. That limb is like a spring and after repeated bending back and forth those chrysals will grow, they have to.
+1
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It will hold, but for how long? The truth of the matter is underneath that ultra thin laminate is a hornets nest held together by glue. Eventually after repeated shots that chrysal will expand to the back causing an explosion. It doesn't matter that the tiller is corrected after the lam is added. That limb is like a spring and after repeated bending back and forth those chrysals will grow, they have to.
If you thin the Birch so that the remaining wood, and chrysals, are near the neutral plane then you should be ok.
I made a sinew backed BC recurve many years ago that developed horrid chrysals. I worked the Cherry down and glued a 1/4" thick strip of Osage on the bow, it's still holding. In fact it's more than just holding, it's a power house of energy.
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3mm isn't nothing on the thickness, though That is going to really raise the draw weight.
If I were you, I would definitely work down below the chryshal, and then add the belly (and hard maple is fine belly wood, but not super belly wood) and really do your best with the glue joints.
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3mm isn't nothing on the thickness, though That is going to really raise the draw weight.
If I were you, I would definitely work down below the chryshal, and then add the belly (and hard maple is fine belly wood, but not super belly wood) and really do your best with the glue joints.
would something like hickory or walnut be better as a belly?
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If those two are all you have, Id choose the hickory.
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Hickory x2
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well ladies and gents... award to biggest nob of the year goes to... me! those compression fractures? they turned out to be chatter marks from scraping. so alls well i think XD i still think ill belly lam for the heck of it
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NOOOOOOOB!
Kidding. I kid!
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Haha no its dead honest truth. Im a noob xD and here comes a noob question. Which is a better compression wood. Maple or oak? And does anyone use hemlok? (I assume not)
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Final question. If i attempt a belly lam, how would best prepare the pieces for laminations? Juet glue it? Sand it? Rasp marks on both sides?