Primitive Archer
Main Discussion Area => Bows => Topic started by: lukelawrence171 on August 12, 2014, 01:44:33 pm
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i was pulling back a bamboo backed bow that i finished yesterday and the bow is well tillered it was put together i have made bamboo backed bows before but this was the first time i have ever heard that noise it was right after i had put the string on the bow so the only thing i would think it would be is the string grove setting into place but it has never been that loud and there is no cracks on the bow that are obvious
what could it have been? should i pull it back again? what should i do i have never worked this hard on a bow and i would hate for it to break. :-[
i just went back to the bow and the bamboo is ok it seems to be the osage belly when i bend it backwards
it makes a weird crackling sound
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Maybe excess glue or a thick glue line?
My first thought was string settling into the groove same as you. A load of wax round the nock should eliminate that possibility just to be sure that's not it..
Del
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Maybe excess glue or a thick glue line?
My first thought was string settling into the groove same as you. A load of wax round the nock should eliminate that possibility just to be sure that's not it..
Del
yea i wish that was what it was i just posted pics :-[
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Did the overlays delaminate? I had that happen before and it sounds similar to what your saying.
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no its the belly does anyone know how to fix it?
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I doubt you heard those "cracks" make noise. They are called frets or chrysals and are compression fractures. Apparently the belly is bending more there then anywhere else. There is no real fix for frets. The only thing you could do is reduce the belly thickness and add a belly lam of a compression strong wood.
Have you checked the boo backing real well. I'd suggest you take a cotton ball and rub it lightly up and down the back. If there is a splinter lifted it will snag the cotton.
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Oh dear...chrysals... horrid things that go much deeper than you'd think (at least 4mm!)
No real cure except rasping 'em out adding a belly patch lamination.
Maybe the boo was too thick and overpowered the belly.
Del
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Wow have never seen that on osage
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Its your osage grain that bit you.
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I learned a trick that will stiffen enough that it will be safer than it is right now. Take sinew or artificial sinew and just wrap and glue and pray the bow stays together.
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The osage is failing in compression and basically erupting upon itself. Its the only direction it can go when forced to move. Wrapping it with anything will do nothing. Wraps can work for tension failures where as the backing or back is popping upward.
Are the chrysals on the upper limb just above the handle 10" by chance?
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Bamboo is over powering the Osage. I'd say it's too thick.
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Is the belly rounded? Can't tell from the picture and where is it on the limb?
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Looks like right at the end of a fade to me.
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I echo what has been said. Those cracking noises don't come from those chrysals in the belly. Inspect the glue line real closely and use a cotton ball to rub the back.
I don't know what the unbraced bow looks like, but judging from the braced picture, the bow bending mainly near the handle. That would just be bad tiller, and explain the localized chrysals. It's going to be hard to salvage this bow. Your best bet would be to re-tiller it so the midlimbs bend more. That relieves pressure from those chrysals and probably stops them from getting worse. But then you still have to tackle the problem with the cracking noise...which is a different problem in itself.
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Whilst those look a lot like chrysals, they look too me like the limb has been twisted side to side( the cause is likely that there is short grain across the belly).Essentially tension cracks on the side of the limb, rather than a compression fracture.
You can usually feel chrysals on a braced bow, but not when its unstrung. If its what I suspect you would likely feel the cracks both when braced or unbraced.
Whatever the cause I'm afraid that bow is an accident waiting to happen, don't shoot it.
Hamish.
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To me it looks like the bow is very narrow and the belly is very rounded. Thats a good recipe for chrysals.
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I agree with Badger. Boo backed osage with a high crown kn the belly focused all the compression forces into a small surface area increasing the pounds of force per square inch by reducing the number of square inches the belly has to disperse the compression. Convex bellies act like a lense and focuse force to its most raised section.
There is a way to mend chrysals without cutting on it but on this bow id say its a lost cause.
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That's why I asked if the belly was rounded.
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He certainly hasnt answered many questions directed at helping him has he? It sure looks like a very rounded belly to me.
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appears your facets caused the situation...rounding the belly as you did puts all the stress on the center of the osage.....gut
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yes, thanks guys the bow does have a very rounded belly i did that because the last bbo i build took alot of set
I think the main reason for the chrysals but the grain of the board had alot to do with that there was alot of grain run off in that area of the bow perpendicular to the limbs so some of the grain might have given out in that area. i dont know yet weather ill just sinew rap that area or add a new piece of wood over it, but thanks for the imput guys, I still have alot to learn when it comes to laminated bows
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yes, thanks guys the bow does have a very rounded belly i did that because the last bbo i build took alot of set
I think the main reason for the chrysals but the grain of the board had alot to do with that there was alot of grain run off in that area of the bow perpendicular to the limbs so some of the grain might have given out in that area. i dont know yet weather ill just sinew rap that area or add a new piece of wood over it, but thanks for the imput guys, I still have alot to learn when it comes to laminated bows
You say you rounded the belly more because your last bbo took too much set ??? Well you kinda went about that the wrong way. Flatter bellies equal less set. The more round the belly is the less room there is to spread out the compression forces and in turn you get more set. Osage can usually handle a rounded belly but you went a little too round for your grain configuration. If it were mine I would string it up and hang it on a wall somewhere. Chrysals are not worth trying to fix in my opinion.