Primitive Archer
Main Discussion Area => Bows => Topic started by: Drewster on June 25, 2015, 04:16:41 pm
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I was shooting in my first Mollegabet and it broke just before I got to full draw this afternoon. It is also my first bow made of black locust, so it's a bummer for sure. If any of you experiences guys can help determine what might have caused this, I would appreciate it. Don't want to make this mistake again if possible.
I had shot it about 30 times starting at half draw and gradually increasing my draw length. When it broke I was probably at about 26" or 27". I had not gotten to full draw......my 29 1/2" or so. Maybe about 27" a few times on the tiller board. I had gotten this bow braced and drawing to 25" @ 45# more quickly than I usually do so had not exercised the limbs as many times as I normally do. The back was smooth from my scraper but I had not done the final sanding yet. I'm wondering if either of these two factors contributed to the break or just my bad luck on this one?
Thanks for any help or feedback you might have.
(http://i1169.photobucket.com/albums/r509/drewsumrell/Busted%20Molly-1_zps0oisvbp8.jpg) (http://s1169.photobucket.com/user/drewsumrell/media/Busted%20Molly-1_zps0oisvbp8.jpg.html)
(http://i1169.photobucket.com/albums/r509/drewsumrell/Busted%20Molly-2_zpsnjsnlocd.jpg) (http://s1169.photobucket.com/user/drewsumrell/media/Busted%20Molly-2_zpsnjsnlocd.jpg.html)
(http://i1169.photobucket.com/albums/r509/drewsumrell/Busted%20Molly-3_zpsabwykbux.jpg) (http://s1169.photobucket.com/user/drewsumrell/media/Busted%20Molly-3_zpsabwykbux.jpg.html)
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That stinks man. Everyone breaks some though. Did you chase a ring on it? How thick was the ring? I've never used black locust before. It broke clean looks like maybe a weak spot there. Do you have a picture of drawn?
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That's a clean tension shear Id say, don't know why. Kind of opposite of what locust will typically do. It will compress and fret first because its generally mean in tension.
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Man that sucks. I guess that's why I like white wood , cause no ring to chase. I blew up an
Osage not long ago. It was my first Osage. Limb broke like yours.
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That's a clean tension shear Id say, don't know why. Kind of opposite of what locust will typically do. It will compress and fret first because its generally mean in tension.
+1. The only tension failure I've had with locust was due to a cut pin knot/ring violation.
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Mr. Drewster,
Sent ya an email bud.....you was about 5-10 scrapes (outer half of @ working limb) from a killer bow.....just a bit too much force at the grip fade. Get ahold of me ....maybe I can get you a chunk of ironwood.
rich
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Transition into the fade is the same thickness. This has happened a few times to me, it became overly stressed in that area. Thats my 2 bits worth.
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Alwayslookin, yes I had removed the sapwood and chased a ring for the back. It looked good.
Half eye, thanks, I'll be in touch.
I'll be better tuned in to tillering the next one. Live and learn. Thanks everyone for the feedback......most helpful.
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Sorry man, I broke one last week in the exact same spot. It hurts.
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Did the bow show any signs of chrysaling before it broke. You might be able to still see them.
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Clean tension break,fungus maybe?I think folks follow the bibles by getting them to bend to much in the inners to a fault.that's my take anyways.it goes against Tim bakers mantra,witch I believe to be the grail in wooden bows!
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Badger, no signs of chrysals at all.
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Just use Osage haha. That shouldn't have broke if your back was clean and it was long enough.
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Locust is very strong in tension. It could be fungus although locust is pretty fungal resistant but there is one around that causes the rings to delaminate. I've seen lots of whitewood break like that but not woods like locust, osage or mulberry.
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Pat B, can you see the fungus in locust? Since this is the first locust I have tried to make a bow with, I'm not familiar with what fungus infested locust looks like. The break was a huge surprise for sure. The tiller was not perfect. I was still fine tuning a bit but I certainly didn't think it was off enough to cause this type explosion.
Sure appreciate everyone's help.
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One more thought. If the wood was too dry, would it have caused a break like this. I had put the stave in my hot box for five or six days at 95-100°, 35-38% relative humidity. The stave was only loosing .2 gram of weight a day so it must have been getting pretty dry. Just a thought.
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I've had two black locust break just like that. One was rawhide backed and snapped clean through at an ever so tiny pin knot at mid limb, broke right through the rawhide too. Any chance there was an unseen pin knot at your break Drew?
Now that I think about it I've had three tension breaks with BL. The third one I forgot about was just a few weeks ago, no frets, no pin knots and no visible set taken. Had it looking good I thought at 20" and pulled to 21" when it exploded. When I accessed the situation I came to the conclusion that I had gotten this one too dry by keeping it in the really hot hotbox for a couple weeks after floor tiller. Tossed it aside and vowed to forget about it,..... and did until now. ;)
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Looks like I was typing my reply at the same time as your last one Drew. The potentially too dry bow I described was in the box apprx. 2 weeks at about 115*. I only had it out about 6 hours when I got it tillered to 20" draw and snapped her. Too dry may very well have been the cause of yours failing too.
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Drew, it was more of a feel thing rather than a see thing. The early wood had a more grainy feel and it would delaminate when it was stressed. The latewood was sound on the locust here. The early wood would let loose. I'm surprised it broke across the back.
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I still can't picture that break coming from anything other than a pin knot or I suppose low mc, though I pull my locust no more than two hours after cooling from heat treating/bending. The pin knot failure I mentioned was pretty violent, the whole back ring on the one limb delaminated and one splinter embedded itself in the sheetrock. No experience over-drying locust here.
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Hi Drewster, don't want to sound silly here, but I'm going to anyway aren't I? But, are you sure that is locust? On my computer it just doesn't have the right colour, some how reminds me more of ash - had an ash molly do exactly the same thing at the same place after I had shot it about a hundred times. Shame as it was a fast bow.
Prignitzer
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That was my question but nobody else but Prignitzer said it....That don't look much like any black locust I've ever seen....I woulda said ash or hazel or maple, something like that just looking at the color of the wood...I've seen maple breaks that look just like that.....Unless it's locust sapwood and then the dark heartwood doesn't even show up on the thickest part of the grip.....
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It looks a lot like a lot of the locust I use, especially looking at the pin knot and how the porous ends of the rings are so much darker looking at them straight on than skewed. Furthermore most (all?) ash has darker early wood than late. I'd pick it out as locust without being told.
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Can you provide dimensons: length, width, thickness where it broke etc. To me it looks a bit narrow for such a design.
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I've got another molle at just over 13/8" wide just out of the fades and that's pretty normal for anything between forty and fifty pounds and normal draw length. If the locust was underbuilt it should chrysal like crazy and fold before it snaps its back, but the dimensions would still be helpful.
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The stave is most definitely locust. I split the stave out of the log myself. I noticed the wood looked kinda "faded" too in the picture. I think it was the combination of florescent and natural light in my shop, but definitely locust. My camera just didn't depict the color accurately.
The bow was 69" ntn, 1 3/4" wide at the fades and tapered to 1 1/2" at the levers. The belly was slightly radiused. The limb is a few thousandths shy of 5/8" just above the break. It should have worked.
After these discussions, I'm thinking the cause was that the wood was too dry. I just looked again and I cannot see any evidence of a pin knot. The wood in that area looks clean.
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Fades look good form my seat. I don't see that being a culprit.
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i always blame my breaks on elves... they sneak in and sabotage everything... lol