Primitive Archer
Main Discussion Area => Bows => Topic started by: luke the drifter on April 27, 2011, 11:29:33 pm
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i have a Osage bow that has about 2.5 of string follow/set(?). will backing it with sinew take some of that out or will i have to boil it and put it in a form to take it out. i am looking to lose about an inch off the string follow. it is about 66 inches long and 1.25 inches wide at the handles gradually fading out to the tips. if i boil it will it weaken the wood?
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To my way of thinking sinew will pull the bow back from the set, and even more so if you put a little reflex into it first. But (and here I go tossing my 'but' around) set in a bow is caused by the belly failing slightly, fibers are crushed behond their endurance and adding reflex to the back doesn't cure the belly ache it already incurred. In my opinion, you would make better use of the glue and sinew to make another bow and sinew it before you do the final tillering.
Now, having said that I am going to sit back and watch someone come in here and prove me wrong! I look forward to hearing from the rest of you out there. Thanks.
Oh, even with the set that the bow already has...does it shoot well? If so, call it a day and move on to the next bow.
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JW, I'm going to side with you on this one. I would never waste good sinew (considering the time and effort to process and apply) on a bow that's seen its day. Nor, would I consider using sinew as a fix for a poorly built bow. Make another (better) bow with intentions of sinew backing it. Timely yes, but well worth it!
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Hi Folks, I'm of the school of "Fix it 'till it's broken." I think Luke may still improve this bow.
Luke, if you haven't already tried it, heat treating the belly can remove set and help keep it from coming back. Try pulling the bow into slight reflex with a simple form and then heat treat the belly. I can guarantee the set will be gone when you pull the bow from the form. Do not string or pull the bow for a few days to allow the wood to re-hydrate. When you string it you will probably find that the bow has gained a few pounds and may need re-tillering. Some of the set will probably return as you tiller and shoot in the bow, but probably not the 2.5" it has now. The heat treatment causes the belly fibers to collapse and get a little denser.
Now assuming that worked, you can sinew back the bow as a safety factor ( lessens the chance of breakage or set.) Sinew backing will also add another ~5# to the draw weight. JW & MW are both correct in saying that sinew backing is a lot of work.
Ron
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m-p
are you talking dry heat?
luke
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Some people only sinew back their bows after it has been fully tillered, in which case such bow could have picked up a couple inches of set. I would go ahead and sinew back the bow but I would do it a bit differently. Since you will most likely have to tiller the bow again anyway I would cut 2" from each tip first. Then I would reverse string the bow so that it will have at least 2" of reflex to start out with and then sinew back it. But then that's just me
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You can only had reflex while green by puting it on a caul. Set is crushed wood sells they can't be repaired. Sinewing won't fix the wood cells but will ad reflex and may be enough to get rid of or strind follow. I have fixed string follow in a couple bows this way. But I like to get my bow to floor tilller ad the sinew then tiller the bow to it. But it can fix some string follow.
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You can only had reflex while green by puting it on a caul. Set is crushed wood sells they can't be repaired. Sinewing won't fix the wood cells but will ad reflex and may be enough to get rid of or strind follow. I have fixed string follow in a couple bows this way. But I like to get my bow to floor tilller ad the sinew then tiller the bow to it. But it can fix some string follow.
Actually crushed wood cells is when you get chrysals and there are more ways to induce reflex than by putting a bow on a caul while green. Set is a combination of stretched wood cells on the back and compressed cells on the belly. The compressed cells are when any air spaces in the wood are forced out and/or a certain amount of deformation of these cells happens, doesn't necessarily mean they have been crushed though.
Just to clarify; the generally accepted definition of set is the permanent deformation of the bows limbs so if you use some method of removing this "set" then you are basically taking it out.
String follow on the other hand is the temporary deformation of the limbs that you get from having a bow braced and shot for awhile, the bow usually recovers this over a few hours
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I think Marc gave you good advice if you insist on adding sinew. Personally, I'd leave it alone an enjoy it. Make another better bow. Jawge
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Luke, I was talking dry heat. See the chapter in TBB 4. Heat treating involves heating the belly until it scorches. There are variations, some like to use a propane torch... just heat the belly fast and turn it black. I prefer to use a heat gun, go slower ( 20-30 min per bow) and heat the wood on the belly to a mild brown that gives off a toasted aroma.
I suggest this first as it's quicker than sinewing. I agree with Marc that sinewing alone ( your original question) will work. Recurving the tips ( use steam or boiling H2O), heat treating the belly and sinewing the back would all be very likely to improve the cast of the bow. Each would raise the draw weight a little, though retillering would be necessary. If you did all three things you'd wind up with an entirely different bow.
Jawge has a point, but I like trying to make a flawed bow better and use it as a learning experience. Maybe once I've built as many as Jawge, I'll be able to except a less than stellar bow and move on to the next.
Ron
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I am officially changing my answer, but only because I am curious to see the outcome. I hereby change my answer to match Marc's first post.
Pike it 2", flip that sucker around backward, sinew the belly-that-is-now-a-back! You may need to decrown the back-that-is-now-a-belly as a final adjustment to tillering, but you are going to have a pretty interesting bow out of the deal!
You might want to christen the newer and improved bow with the name "B'asswards", or something like that.
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I am officially changing my answer, but only because I am curious to see the outcome. I hereby change my answer to match Marc's first post.
Pike it 2", flip that sucker around backward, sinew the belly-that-is-now-a-back! You may need to decrown the back-that-is-now-a-belly as a final adjustment to tillering, but you are going to have a pretty interesting bow out of the deal!
You might want to christen the newer and improved bow with the name "B'asswards", or something like that.
Why would you want to sinew back the belly?
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M-P, thank you for the compliment, my friend, but all my bows are flawed in some way. Take my last osage bow. It has wind checks the run the length of one limb and a propellor twist. The string leans to one side of the handle. I could not heat because of the glue I used to stick the wind checks together. I've learned the best scenario to get a quiet arrow is to put the string to the right but on this bow I wanted the wind checked limb on the top. That put the string too close to my bow hand. String slap was fierce. I could not tune for silence. I had to flip it around. The tiller is awful looking between the prop twist and such. The bow is in tiller and is quick shooting...one of my quickest. In my younger days I's spend hours and hours trying to fix set, etc. I finally decided t was time better spent learning to make better bows with the stave I had in front of me. Gotta go. Jawge
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Marc,
I thought your post was recommending flipping the bow around so that the set would work like reflexing the bow, thus turning the bow "inside out" so to speak. Since the belly would then become the back, sinewing would overcome any problem with grain violation. I must have been reading it wrong, but it's still an interesting idea.
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I think Marc meant to flip the tips, thus adding a small recurve to them.
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Interesting how different people read different things from my post. Sorry to say you are both wrong. No recurves and no sinew backing the belly, just reflex
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I think what Marc meant is to string the bow backwards, with the string on the back-side rather than the belly-side. This naturally pulls the bow into reflex equal to the brace height. Then sinew the bow's back while the string holds it in reflex, and it will keep this reflex when the sinew dries.
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I think what Marc meant is to string the bow backwards, with the string on the back-side rather than the belly-side. This naturally pulls the bow into reflex equal to the brace height. Then sinew the bow's back while the string holds it in reflex, and it will keep this reflex when the sinew dries.
"ding, ding, Ding" I think we have a Winner ;D
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No, don't do that. That will pop you bow quicker than a microwave will popcorn.
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Well, this is an interesting thread :D.
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Well, aren't we getting a lot of conflicting opinions. I think we all agree that the set probably could be removed. I think we all agree that there's more than one way to do it. The best way, or even whether it's worth the trouble seems to be the sticking point. I still feel that "improving" a less than perfect bow is a learning experience and worth doing. Then maybe the next bow won't have the same flaw.
Now that I think of it though, the my 'next bow' always seems to have flaws too. I guess I'm heartened to hear that Jawge still has the same problem, at least occasionally.
Ron
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No, don't do that. That will pop you bow quicker than a microwave will popcorn.
What? Were you referring to my post?
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George's concern was that if the bow is strung backwards it would fail. And I agree...if it were to be strung to a full brace height.
When I re-read Marc's post, I got the full intent from the following line; "Then I would reverse string the bow so that it will have at least 2" of reflex to start out with and then sinew back it." Reverse stringing with only 2 inches of brace height shouldn't cause the bow to go Orville Redenbacher on him. But it WILL induce reflex as the sinew is applied, reflex that will increase some even as the sinew takes up tension as it dries.
Yup, interesting thread. I still like my initial mis-interpretation of Mr. St. Louis's post best! Turning it arsey-varsey and sinewing what used to be the belly. This thread shows what I like best about this Forum...access to many viewpoints, loads of experience, and people more than willing to share. A lifetime of experience is right here at our fingertips. You people are great!
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Actually using the set in a bow as reflex and sinewing the old belly to form a new back is a Tim Baker idea. I question whether he ever actually used this idea though.
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No, don't do that. That will pop you bow quicker than a microwave will popcorn.
Not likely but then that would depend on what one considers "brace height". The bow could easily take 4 or 5 inches of reverse bracing but tillering the bow out would be more of a handfull and not for the faint of heart