Primitive Archer
Main Discussion Area => Bows => Topic started by: VanceMan on July 05, 2015, 11:39:38 pm
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I have been working on a 55" osage recurve ,with limbs 1 1/2" average width, for awhile now and I have just finished the early tillering stage and I braced the bow for the first time at full brace height. After a few seconds braced I heard a low cracking sound and I carefully unbraced it and checked the back and found a small crack running across the grain. I was always planning on adding 1 or 2 courses of sinew to the back, will the sinew save this bow? It will only pull about 40# right now. I think the main reason for the crack is that the growth ring I chose for the back was too thin (but I did so because I planned on using sinew). Any help is appreciated, thanks!
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I have only seen these type of cracks in one bows back, mine. I didn't get them right away, it took years and thousands of arrows. I loved the bow but didn't trust the cracks so I bamboo backed the bow.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/backchrysals.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/backchrysals.jpg.html)
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hmm. Maybe they don't go all the way through the ring? Idk. Worse case scenario say that they do, you think sinew backing would fix it?
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I'd try chasing the next ring, especially if it's thin.
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I'll admit I've only worked a few pieces of osage, it seems to my locust-trained intuitions that almost half an inch is still really thick for forty pounds. If it is an issue the sinew, heat treating, and additional reflex can all up the poundage. Seems like a sound last resort ;)
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Okay so I just remeasured with the calipers, and I forgot that I hit it with the course sanding already and its at 4/16" right where the crack is at. The crack is at midlimb and the bow tapers from a little less than a half inch at the fades all the way to 3/16" at the nocks. Im not sure I can still tiller it to 40# if I chase the next ring can I? I have recurved the last 8" and the bow already has some reflex...how much poundage would a layer a sinew do me? thanks for all the input!
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You won't get much draw weight from one sinew layer. Maybe upto 5 lbs.
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will the sinew layer keep the bow from breaking at that crack?
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I really don't know about sinew's back-saving properties, haven't backed a bow with it myself and I'm pretty careful with my backs. Still thinking about the last resort here ;D
Can you guess about how much removing the ring will cost you? Going from a flat profile to ~3" starting reflex can really up the potential poundage and force-draw curve, plus the heat treating itself has added as many as seven pounds for me, and then you've got the sinew which like Mike said would need to be more than one course for anything over five-ish pounds.
How thin is this ring? Pic?
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Here are pics of both tips. As you can see the rings are pretty thin : /
Also here is a side profile of the bow.
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According to your measurements your taper is all fubar, nearly a 1/2" at fades and mid limb on a 55" bow its 1/4" and from there only tapers 1/6" you should have a smooth taper from fade to tips any pics of it braced
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sorry no pics of it braced :(. I don't wanna risk that again yet. What should it taper to? When on the tillering stick it looked decent to me. The recurves are not as wide as the midlimb so I thought it best not to taper thickness too much for fear of the recurves being under too much stress. What thickness should they be at? and also will a sinew backing take care of that crack problem? Thanks!
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I would not waste the time and sinew on a bow that will maybe survive.
Its very hard to see in the photo, but any crack across the grain is never a good thing.
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Okay so I had a hunch so I grabbed my knife and carefully excavated the damage, a appears that just a small flake was all that lifted off. The damage was very shallow. What do ya think? Is it worth it to continue?
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Maybe that was just a bit of the previous ring that hadn't been completely scraped away... like a small island?
From what I've seen it's an all or nothing thing. Just shoot it, it'll either explode or it won't ::).
If you really want to do something... maybe a rawhide backing will give some reassurance with minimum effort?
Del
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I would not waste the time and sinew on a bow that will maybe survive.
Its very hard to see in the photo, but any crack across the grain is never a good thing.
You would be surprised with what you can do with sinew
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The stave is 54" with a rather large handle area and what looks to be very little working limb.
What is your draw length?
That crack looks like the bow was pulled to far for its design.
I would back it and wrap the suspect area with sinew after I backed.
Rawhide is good.
I would probably just start another.
Jawge
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I second the exploding!
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I would not waste the time and sinew on a bow that will maybe survive.
Its very hard to see in the photo, but any crack across the grain is never a good thing.
I agree with Goat. If I'm going to sinew back a bow it is going to be designed and planned for sinew from the very beginning.
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I would not waste the time and sinew on a bow that will maybe survive.
Its very hard to see in the photo, but any crack across the grain is never a good thing.
I'm with these two, if you want to try and fix it go with jawges plan
I agree with Goat. If I'm going to sinew back a bow it is going to be designed and planned for sinew from the very beginning.
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I would not waste the time and sinew on a bow that will maybe survive.
Its very hard to see in the photo, but any crack across the grain is never a good thing.
You would be surprised with what you can do with sinew
I've only made 4 sinew backed bows, no surprise for me. All 4 were clean staves though, I've never done a sinew bandaid before
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No it is definitely the wood below that is showing. Now that the backing is violated, im pretty sure my only options are to chase the next ring (though im not sure I will get 40# with these dimensions), or use sinew to provide strength and security (im not sure rawhide will fix a violated back will it?). Anyway, I have the sinew already prepared I just want to know if someone has been here before and got a successful bow out of the situation.. thanks!
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Me personally I would not spend the time and energy into fixing that. It will only get worse never get better. Sinew is a performance enhancer not a permanent cure all. I would put it in the corner of shame for a further date and if you do not have a corner of shame it's about time you start one >:D
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Haha yup. What would a bowyer be without a corner of shame?
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If you've got the sinew prepared then have at it! I'd be looking to use about 2 to 2 1/2 ounces on that bow.
You will learn something from doing it anyway no matter what happens.
As George says though your handle is too long. See if you can rework it so that the grip itself is 4 inches long, the fades 2 inches and then straight into working limb.
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I think I will put a good thorough single course of sinew on it and retiller in about a month. And yeah that is a good idea with shortening the handle and fade section. The bow used to be 2inches longer than it is now before I piked it so that's why its too big..
Although I must add that I have already started on another osage stave :D
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Me personally I would not spend the time and energy into fixing that. It will only get worse never get better. Sinew is a performance enhancer not a permanent cure all. I would put it in the corner of shame for a further date and if you do not have a corner of shame it's about time you start one >:D
Oh and trust me I have a corner of shame lol. I have been making bows for 5-6 years now and I have about 10 un-usable/compromised bows and only 3 bows that turned out well. I have an Hickory English longbow, white ash flatbow, and osage shortbow.. so my failure rate has taught me to take it with a smile lol.
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What would have necessarily been "designed" differently about this bow if it was intended to be sinewed in the first place?
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Im not sure I understand the question, but it was my intention all along to sinew this bow... my original question was whether or not the backing quality of sinew was enough to prevent the crack from getting any worse and if not what else should I do to prevent a break
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Im not sure I understand the question, but it was my intention all along to sinew this bow... my original question was whether or not the backing quality of sinew was enough to prevent the crack from getting any worse and if not what else should I do to prevent a break
Ah, I think I get what you are asking. It was originally 2" longer than it is now, and therefore had larger fades (I wanted longer fades to allow the limbs to store more energy in the early draw). But since I have piked it 2" and now I have reduced the fades and it has a 4" handle, and is still destined for sinew. Except now the sinew is primarily to keep it from breaking and secondarily for performance.
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Here is a picture of the bow now. I will most likely sinew tonight if there are no more issues.
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In my admittedly very limited experience, backing a crack doesn't save the bow. In my case, it was rawhide over a crack, and I think it made the failure even more violent and dangerous. Luckily it failed on the tillering tree when pulled to 25" at 50#. Had I been holding it, it could have gone badly. I think the rawhide held things together much longer than normally would have happened, and when it failed the energy stored made for a spectacular explosion. About a foot of limb almost stuck in the drywall of my garage ceiling.
Be very careful if you go forward with this bow!
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Thanks for the warning! From what I have researched in books, sinew is much more effective at providing a good backing so I think I will be better off than with rawhide.. but I will still be cautious! The only reason I am worried is that knowledge found in books is not always unbiased and is not necessarily the whole story so I'm looking for lots of personal experiences to draw from on this matter...thanks for sharing!
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if the crack is gone,, then that is not an issue,, if you sinew back you have a chance to make the bow,, but I think the tiller will be pretty tricky cause of the reflex,, but if you get the taper even it should work,, if it was my bow I would give it a try,, and not think I was wasting my time,, even the most perfect design and wood can have hidden flaws effecting the outcome,, it would be easier to tiller with recurves a little smaller,,,, I think the cracks were from a little too much heat,,, but just guessing,, give it a try,,
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If I chose to try and save it, I would sinew it, BUT, I would put 3 courses of sinew on it. I think a small patch and 3 courses of sinew would fix the weak spot and allow you to make weight.
I made a straight standing snakey osage selfbow once and shot it for several weeks when it lifted a splinter by a cluster of pin knots. I superglued the splinter down, roughed up the entire back and then put a sinew patch, about 2 1/2" long over the area and then layed down 3 courses of sinew over the entire back, then diamondback skins, and I have shot it and hunted with it for many years. It's one of my favorite bows and I trust it completely. Sinew is better than rawhide when it comes to repairs like this. Rawhide is more for protection/preventive maintenance... before anything bad happens.
One other thing to consider... you have a LOT of recurve in that bow already, which can make it tough to tiller and maintain alignment. If you put sinew on it, as it dries, the sinew can shrink and try to pull it into even more reflex, especially with the limbs so thin... so measure it beforehand and as it dries, and if it starts moving too much, strap it down or exorcise it or something :)
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A sinew patch I put on an Elm static recurve 10 years ago after the bow developed a crack on the back during hunting season. It's still shooting
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If I chose to try and save it, I would sinew it, BUT, I would put 3 courses of sinew on it. I think a small patch and 3 courses of sinew would fix the weak spot and allow you to make weight.
I made a straight standing snakey osage selfbow once and shot it for several weeks when it lifted a splinter by a cluster of pin knots. I superglued the splinter down, roughed up the entire back and then put a sinew patch, about 2 1/2" long over the area and then layed down 3 courses of sinew over the entire back, then diamondback skins, and I have shot it and hunted with it for many years. It's one of my favorite bows and I trust it completely. Sinew is better than rawhide when it comes to repairs like this. Rawhide is more for protection/preventive maintenance... before anything bad happens.
One other thing to consider... you have a LOT of recurve in that bow already, which can make it tough to tiller and maintain alignment. If you put sinew on it, as it dries, the sinew can shrink and try to pull it into even more reflex, especially with the limbs so thin... so measure it beforehand and as it dries, and if it starts moving too much, strap it down or exorcise it or something :)
Thanks for all the input guys! And yeah Im guessing im going to see some massive reflex due to the sinew, so I was planning on doing 2 courses. But you think I should do a patch? Ive never had to do one before, how is it done and how much? Should it go under the sinew backing or over? Thanks!
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A sinew patch I put on an Elm static recurve 10 years ago after the bow developed a crack on the back during hunting season. It's still shooting
How much sinew did you use for that patch and was the crack in your bow somewhat like mine?
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My question was directed at those saying the bow needed to be designed for sinew in the first place to make it worthwhile doing. What about this design makes it a poor candidate?
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My question was directed at those saying the bow needed to be designed for sinew in the first place to make it worthwhile doing. What about this design makes it a poor candidate?
Well nothing as far as I know. It seems to be the perfect candidate to me...compromised growth ring, needs sinew to bring it to 28" draw, and extra protection for the highly stressed recurve. Sinew sounds like a good idear to me ;D
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My question was directed at those saying the bow needed to be designed for sinew in the first place to make it worthwhile doing. What about this design makes it a poor candidate?
Nothing except for the crack across the back of the limb. The crack is why I wouldn't sinew back it, not the shape or design. Me personally, I won't sinew back a bow with a flaw like that. Yes it will probably hold and shoot fine but there is a chance that whatever caused it to crack in the first place will cause it to fail again. If I find something like that in a bow I'm working on its going in the burn pile and I'm starting on something new. I'm not much into patching problems.
When I said "if I'm going to sinew back a bow it is going to be designed and planned for sinew from the very beginning", that included having a clean growth ring on the back. It had nothing to do with the design of his bow. I never said his bow wasn't a good design for it.
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I side with the I wouldn't put time into sinewing it because its shown you a flaw in it and has been compromised already....but to each his own... plus I'm not much of a fan of sinewing either in lots of cases. But that's just me. Either way if ya do or don't youll find out what you like best,and what works best for you,and you will develop ur own opinion after ya make some more bows.
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I'm with Clint and Chris, but again that is just me, I will make a wrap or some minor repairs and might even do some preventive work on one I think could give trouble but after I get something like that in the back in a high stress area, a splinter raising is one thing, a crack across the back is another IMO. I'd cook brats with it. ;) :) Good luck, hope it works out for ya. :)
Pappy
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Do you have any idea how strong the bow is now? You said you had it braced but gave no indication of its present draw weight. As thin as those rings are you might get away with taking it down one more ring. If it came in just a tad light you might even shorten up your hooks a little bit, those long hooks can be hard to deal with anyway.
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I think I mentioned earlier the draw weight...i only ever pulled it out to 22" because it can't handle any more than that without sinew..and it seemed to be around low 30's#
Probably low 40's at 28"
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I'm with Clint and Chris, but again that is just me, I will make a wrap or some minor repairs and might even do some preventive work on one I think could give trouble but after I get something like that in the back in a high stress area, a splinter raising is one thing, a crack across the back is another IMO. I'd cook brats with it. ;) :) Good luck, hope it works out for ya. :)
Pappy
Well I've heard stories of people repairing limbs that are completely cracked through with sinew and since mine only has the back ring compromised I thought it would be worth it... Meh if it breaks oh well
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Don't blame you at all, you just ask for opinions and that was mine, you seemed to have your mind made up before you ask anyway. ;) Pappy
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Don't blame you at all, you just ask for opinions and that was mine, you seemed to have your mind made up before you ask anyway. ;) Pappy
Haha maybe I did idk! I think the only reason I'm willing to risk it is that I'm working another stave right now so either way I'm sure to have a bow ;D
And I really appreciate the opinions! It's good to hear from experienced bowyers
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Have you made many bows with that much reflex in the outer limbs(not to insult just asking)they can be a pain to get to break over.if you are fairly new I would set it aside for a while before continuing. If it were me I would take it down a couple. Rings to about a 20# at 28", add a thin bamboo backing and you would end up with a 50-60# when finished,my.02 cents
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Have you made many bows with that much reflex in the outer limbs(not to insult just asking)they can be a pain to get to break over.if you are fairly new I would set it aside for a while before continuing. If it were me I would take it down a couple. Rings to about a 20# at 28", add a thin bamboo backing and you would end up with a 50-60# when finished,my.02 cents
I've made one other with this much recurve...i gave it to a friend. I got it to tiller without breaking by wrapping the recurves with sinew then mainly removing wood on the recurves. It eventually got a nice even tiller but yeah its hard
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I used 1 course on that bow that spanned the crack by 3" on both sides and the crack was much the same.
Personally I would fix it, at the very least doing that will add to your knowledge base.
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I used 1 course on that bow that spanned the crack by 3" on both sides and the crack was much the same.
Personally I would fix it, at the very least doing that will add to your knowledge base.
Did you patch it long-ways or cross-ways down the bow (if that makes since). Also, do you think I should patch it special even if I am sinew backing this bow? I don't know because I've never had a crack like this before...ha.
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No just lay the sinew down evenly.