Primitive Archer
Main Discussion Area => Bows => Topic started by: turtle on October 15, 2015, 12:57:23 am
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Had this bow break on me sunday . It had been my go to bow all summer and seemed to be holding up fine. Appears that the back let go on the high crown. Limb that broke was dogwood and I thought a high crown was fine with a weeker compression wood like dogwood. What do you all think was the problem.
Original bow post is here.http://www.primitivearcher.com/smf/index.php/topic,52613.msg712957.html#msg712957
Pics of the break.(http://i1067.photobucket.com/albums/u437/stevenbennett2/Hickwood%20bow/IMG_20151012_171305026.jpg)(http://i1067.photobucket.com/albums/u437/stevenbennett2/Hickwood%20bow/IMG_20151012_171320695.jpg)(http://i1067.photobucket.com/albums/u437/stevenbennett2/Hickwood%20bow/IMG_20151012_171338200.jpg)(http://i1067.photobucket.com/albums/u437/stevenbennett2/Hickwood%20bow/IMG_20151012_171427288.jpg)
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yes, it looks like the back broke first, and you would have thought that all that character would be the weak point. has the bow been kept in drier conditions since you completed it last may?
heck, take it apart again, and find a new upper for the hickory, it will probably miss the frog-eyes now that they spent the summer together
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Damn, that's a shame :(
No real ideas, maybe it got a scratch or a bump at that point on the back, maybe it's dried out a bit.
Del
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I keep a pretty close eye on the humidity in the room I keep my bows in. It was between 45/50% all summer.
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Tension break for sure...why tho? Cant say for certain. But..i do see it broke where it was doing most of the bending. I think your tiller was ok enough,but it does look like you had a "crowded" tiller in to small of an area...and thats where it broke...i realize theres a knot there,but it couldve had more bend above to the fade and a hair more below and it wouldve distributed the load a lil better. I dont think it was a game changer causing the break,but who knows. Maybe it contributed to it. Add the fact the crown was pretty high there,even tho dogwood is pretty strong in tension and elasticity.
Sorry steve
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It does look like you asked a limited section of good wood to take all the strain.
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This is a tension brake for sure.
Dogwood is very sensitive to pin knots on the back.
Dead knots on the belly are hard as a stone and prevent evenly bending, they should be drilled out to the middle of the depth (to the neutral zone) - don't know if there was something like this.
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Thanks for the replies. I'll just chalk it up to less than ideal tillering and move on.
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I think you have to look at it pretty hard to find fault with the tillering job.
There is always a place in any design where the limb is strained is more than some other part of the limb. (unless it is a perfect arc of circle "D" bow)
when working at the max strain, "stuff" just happens sometimes
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In hindsight it looks like you may have gotten a little chicken around those knots and that moved the bend out a bit. I would have done the same. Not that that means a lot :) :)
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I would say a compression failure due to slight hinging or too much pressure in one area.
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Looks like a tension break on a heavily crowned save where the stress concentrated right down the middle of the back.
On sapling bows I leave them 2-3 inches longer than I usually do.
Usually my bows are 63-65 (roughly) in for a 26 in draw.
For a sapling I add 2-3 in to that for my draw depending on the condition of the back.
Jawge
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IMHO too much crown, too narrow, and possibly too dry. Though quite unpopular, I would have decrowned it. That's basically what the bow did to itself.
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Do my eyes deceive me? It looks like there's a pin knot at the very start of that tension break?