Primitive Archer
Main Discussion Area => Bows => Topic started by: sulphur on October 14, 2009, 10:51:46 pm
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anybody ever sinew a bow using tb3?? whats different? how do you prepare the back of the bow etc, etc. any help would be appreciated. i am about ready to try this on a 57" osage recurve.
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My guess is that when you put sinew on a bow you have re-constitute it first by soaking the bundle in water...i believe with titebond 3 the water may get sealed in after the glue dries because it is a waterproof glue....titebond liquid hide glue on the other hand is water solulable....so maybe that would make a difference...im not totally for sure but I bet that has something to do with it
-Ky
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I used it a couple of times for sinew and for snakeskin backing, worked great with the added benefit of water proofing. I believe the water resistance isnt until dry since it is a waterbased formula. I had not lifting or delamination.
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I didn't like how it laid down with TB3. I liked Knox much better along with snake skin using TB for the skin.
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Sinew, the shredded fibers of animal tendon, was used for cordage, binding points on arrow shafts, and for backing material for bows. Why sinew? What are its properties which make it so desirable for these uses? Obviously it is tough and it shrinks when it dries, but how much? A fairly extensive search of the Stanford library, asking professors of biomechanics, mechanical engineering, and archeology yielded no useful information. It looked like I would have to get my hands dirty and do some experiments on the stuff but first, what did we already know about sinew?
Saxton Pope, a professor of Medicine at the University of California in the first part of this century, an intimate of Ishi's, and an ardent bowman, wrote a delightful little book about Indian bows and arrows titled "Bows and Arrows". He stated that when Ishi made sinew-backed bows he did not worry much about cutting through the heartwood on the back of the bow. This was in contrast to all of the old-time books which describe the fabrication of longbows out of yew, osage orange, or any of the other classic bowyer's woods. The standard caveat when building a self bow (wood only) was to be very careful about having the back of the bow (the part away from the archer) follow the grain of the wood exactly or else it would break where you cut through the wood fibers.
Pope also did experiments with miniature yew bows backed with rawhide or catgut. His conclusion was that adding the backing made very little increase in the cast or ability of the bow to shoot a long distance. Therefore, he concluded, the presence of the backing only protected the back where the grain wasn't parallel and prevented the bow from breaking at full draw. Pope is to be commended for doing experiments but more needs to be done to understand what sinew does.
The Eskimos also made sinew-backed bows but in their frigid and damp climate it was impossible to do anything with glue, so their sinew was applied in the form of twisted cordage tied on the back of the bow. The tension in the backing material was increased by twisting after it was bound to the back of the bow (see Callahan, Bulletin of Primitive Technology #1 & 2).
Reginald Laubin, in his book "American Indian Archery", described his experiences in replicating Indian bows from osage orange wood and sinew. He stated that as the sinew backing dried it tended to shrink and pull the bow into a deeper and deeper recurved position and contrary to the claims of Saxton Pope, it made the bow more powerful. Laubin's book is full of practical experience but nothing very quantitative.
Another article in "Scientific American" magazine on crossbows (January, 1985) stated that sinew has a tensile strength of 28,000 pounds per square inch. This is useful information but it is only 1/3 of what is needed to characterize sinew.
My own experience with the construction of sinew-backed bows started when I saw a backed bow made by a man living in Oakland. A beautiful job. The replies to my questions were that it was deer sinew applied with Elmer's Glue. Did it shoot well? I didn't ask. Several years later I made a short flat bow out of Santa Lucia fir (initially misidentified as California nutmeg), backed it with horse sinew applied with Elmer's carpenter's glue. It was a lesson in the fact that even a knotty, poor piece of wood will make an acceptable bow when backed with enough sinew. My next attempt was a very close replica of a 36 inch Yurok bow in the Wattis Hall of Man, Golden Gate Park, San Francisco. This was a yew wood plus sinew combination with very wide thin limbs. Some very elementary mechanical engineering theory says that the only way you can make an extremely short bow such as this and still shoot a reasonable length arrow is to make the limbs wide and thin. Again I glued the horse sinew on the back with Elmer's carpenter's glue. What a disappointment! It looked very nice but didn't shoot worth a darn. After shooting awhile and then unstringing the bow, I noticed that the bow followed the string (bent towards the archer) but after being unstrung a few hours it went back to its original shape. In general the bow was "flabby". My last experiment was a plains Indian style bow, made from a 48 inch black locust stave. This time I used hide glue to bond the horse sinew to the back. This bow was dynamite, powerful and fast. Did the hide glue make that much difference?
The engineer in me took over. What are the material properties which will yield a superior bow and how can I measure them? The things which matter are the elastic modulus (how much it stretches with a given tension), the tensile strength (how much tension is needed to break it), and how much it shrinks when it dries. In addition, it helps to define some other useful terms:
Potential energy: the ability to do work. When you pull the bowstring back you store potential energy in the bow limbs. The available potential energy is equal to the distance you pull the string back multiplied by the average force that it took to pull the string back to full draw. When you release the string the potential energy is transferred to the arrow, giving it . . .
Kinetic energy: the energy of motion. A perfectly efficient bow would transfer all of the available potential energy stored in the bow limbs into kinetic energy of the arrow.
Elastic modulus: a measure of how stiff a material is. Make a one inch cube out of the material and stretch it with a known force. The cube will get slightly longer. The elastic modulus is the force times the length of the block, divided by the area of the block times the distance the block stretched. Steel has an elastic modulus of 30 million psi (pounds per square inch), hickory has an elastic modulus of 2.2 million psi, black locust has 2.1 million psi, and the measurements I have made on yew wood give a figure of 1.2 million psi.
Tensile strength: keep pulling on that one inch cube of material and eventually you will pull it apart. The force per square inch that it takes to pull something apart is the tensile strength. For tempered steel the number is 400,000 psi, for hickory it is 20,000 psi.
For those of you who wonder: yes, it is very impractical to make these measurements on a one inch cube of material. The one inch cube was cited to emphasize the force per unit area nature of the experiment. In actual practice a much skinnier specimen of the material would be tested.
My measurement of the elastic modulus of a dried, solid horse tendon gave a figure of 411,000 psi. Similar measurements on yew wood yielded 1.16 million psi. This said, much to my surprise, that under the best of circumstances sinew had only 21 to 35 percent of the elastic modulus of wood. Put in other words, and leaving out the mathematical formulas, if you make a yew wood bow of 50 pounds pull and add more yew wood on the back to make the limbs 5 percent thicker, the resultant bow will have a 15 percent stronger pull or 57.5 pounds. If, instead of adding more wood on the back of the bow, you make the bow limb 5 percent thicker by adding sinew, the increase in draw with would only be 2.2 percent or an additional 1.8 pounds. Why bother adding a material to the back of the bow which doesn't add much to its strength? The other 'secret' ingredient must be shrinkage.
I was pretty well convinced that sinew shrank while it dried and this put the sinew backing under great tension. Did the amount of shrinkage depend on the type of glue used? The experiment to find this out was to glue sinew on the backs of two identical strips of 1/8 inch balsa wood. On the first one, the sinew was glued on with hide glue, on the second, the sinew was glued with Elmer's carpenter's glue. The two samples behaved identically. As the sinew dried and shrank it pulled the wood into a curved shape. This experiment showed little difference between the two types of glue, only that the sinew shrank as it dried. Again I took two identical 1/8 inch strips of balsa wood and put a thick strip of hide glue on one and a similar strip of Elmer's on the other (no sinew on either). This time there was a pronounced difference between the two. The hide glue shrank and curved the wood just as much as the sinew, and the Elmer's glue did not shrink at all. Moral of the story: don't use anything but hide glue for applying the sinew. Furthermore hide glue is 'compatible' with sinew since on a molecular level they are identical. The last experiment with sinew was to see exactly how much it shrank when it dried. I pinned one end of a strip of wet sinew to a piece of plywood, and pinned the other end to the short end of a stick that pivoted at one end. Now, when the sinew shrank, the long end of the lever would move through a greater distance and make the shrinkage easier to see. The result was that the sinew shrank 3 percent upon drying.
In conclusion one can say that the benefits of sinew backing on wood bows come from a combination of several effects acting together. They are:
1. As the sinew dries and shrinks it puts the back of the bow under compression. As a consequence, the wood fibers on the back of the bow are not stressed as highly when the bow is drawn.
2. The sinew protects the back of the bow where it doesn't follow the grain.
3. The back of the bow, which is stretched a great deal at full draw, is now a material which can stretch 5 percent before breaking (wood can only stretch about 1 percent before breaking).
REFERENCES
Saxton T. Pope
1980
Bows and Arrows
University of California Press.
Reginald and Gladys Laubin
1923
American Indian Archery
University of Oklahoma Press
This article was first published in The Bulletin of Primitive Technology (Vol. 1, Spring 1994, #7)
E-mail your comments to "Richard A. Baugh" at oldfellah37@msn.com
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Hope that helps. I think everyone who considers sinew backing a bow should read that article.
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Very good info Shadow,thanks for sharing.. :)
Pappy
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thanks shadow thats great info. However i can't dismiss Ed Scotts bows. I believe he uses TB3 when sinew backing. In truth though all i am looking for is an easy way to waterproof the sinew. seems like everyone puts snake skins on theirs and although, that would be cool, i haven't come across any good size snakes. So my next question would be, is spraying urethane or poly over the sinew adequate to make water resistant? i realize no finish is totally waterproof. Or can you use tb3 and cloth over the sinew that was applied with hide glue??
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You could put TB3 over it after it has dried with the hide glue.I seal mine with Tru Oil
and haven't had any trouble.Polly would work also you would just need to put on several coats.
I seal most of my bows with tru oil 6 or 7 coats then the last with Spray polly satin to stop the
shine. :)
Pappy
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Great article Shadow :)
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Great!! thanks guys as always. I am about half way through getting my sinew prepared. i'll post some pics of the patient later on.
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On my bow Elkie, I put down 3 courses of sinew. The first 2 were done with Knox and the last and the snake skin over it were put down with TBIII. I did this to help water proof it. Once it dried well I coated the entire bow with 5 or 6 coats of Tru-Oil and a final quick spray of satin poly. Even with all the "waterproof" coatings it still went from 56#@26" to 45#@26" back up to 55#@26" and then to 65#@28"; all because of the RH changes between here and S W Colorado.
I have seen and shot sinew backed bows that were done with TBIII instead of hide glue. They shot very well but I don't believe you get the same effects as you would using hide glue.
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You could put TB3 over it after it has dried with the hide glue.I seal mine with Tru Oil
and haven't had any trouble.Polly would work also you would just need to put on several coats.
I seal most of my bows with tru oil 6 or 7 coats then the last with Spray polly satin to stop the
shine. :)
Pappy
Pappy, when I put TB3 over sinew thats been put down with hide glue, it seems to dissolve the hide glue some on the sinew. The strands of sinew seem to be more pronounced. Do you ever find this? Maybe I am rubbing and smoothing too much.
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I would like to try TB3, What all can it be used for other than moisture sealing?I'm not sure where to get it thoough or even if it's available in Canada.
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Titebond is a common carpenters glue(PVA I believe) similar to Elmers. TBIII is the waterproof version. It is a good wood/wood glue and it's waterproof element makes it popular with wood bow builders.
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Does it have a stronger bond than other carpenter glues? or am I best to stick with my hide glue?
I guess my main concern would be, is TB any good for laminations ?
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I've used it for backed bows with hickory or boo backs and osage, yew, ipe, black walnut and a few other belly woods and never had a glue failure. You will get a little glue creap though.
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I think I'll give it a try. Can I get it at lowe's or Home Depot??
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You should be able to. I know they have it here.
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Lowe's has it. So do specialty woodworking shops. TB 3 is said to not creep.
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I tried it on a little Ash flat bow with recurved tips, it didn't seem too bad, but the bow broke across the back (one frosty morning on the tiller), I suspect I didn't have enough sinew on it, but the sinew looked dry and fibrous across the break. I found the TB3 seemed to dry out/thicken as it was being used.
Personally I wouldn't try it again, I'd go the natural route.
It's still a very good glue to have around.
(http://i411.photobucket.com/albums/pp195/Del_the_Cat/bow11.jpg)
Del
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OK, you want to hear something really funny. Wood Working magazine tested the major brand glues for strength and water resistance. They submerged the glue joints in water for 24 hours. The TB3 joint failed at about 200 PSI. They pretend it similar to polyurethane glues, but they held up to nearly 1000 PSI. I know you guys aren't going to believe this, but you cannot believe everything you hear from the marketing department. ;) I have thrown bows with TB3 in the pool overnight to soak the glue joint apart, and I guarantee you they come apart.
Lets assume it is waterproof. Why would you use waterproof, or even water resistant glue to apply water soaked sinew? Seems like a problem waiting to happen. If the glue on the outside starts to cure while the sinew is wet, the moisture cannot escape.
When all is said and done, you will have to seal it anyway to keep moisture out so why worry about waterproofing before you waterproof. 8)
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I probably wouldn't use it over sinew as a sealer, because as you pointed out, there may be moisture trapped in the sinew. But for some other applications it may be as good and maybe a little less fussing than using the hide glue. Perhaps for tip overlays and handles ect. As far as sealers go, I have been using Helsmans satin finish and it seems to work fine. It dries fairly quickly so it should be fine over top of sinew. I would still use the hide glue to apply the sinew though.
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Yew and Osage are the only decent bow woods.The ELB is the only efficient bow design.You cant make bows from Kiln dried Lumber.You cant back redoak with Bamboo.Any of these defenses,would not stand up in the Bowyers court today,but for a long time,that was the dogma accepted by the masses.This topic has turned into another one of em.Often when the subject comes up,and it has many times,it is replied to by many who have never done it,done it improperly or are just repeating the same dogma they have HEARD or READ somewhere else.Before we go condemning TB glues for sinew application,Maybe the ones really wanting to know,should consult those who have actually used it with success.People like Ed Scott,who has been mentioned as well as John Scyphers and Mark Baker.There are others as well.Juniper Junkie{Dave} obviuosly has had good results from it,and to the mans credit,has made a few in his day,even sinew backed bows with hide glue,so he can evaluate the differences.Most of the folks i know that have had good success with it,sought out more experienced advice,most often from Ed himself.
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I've sinewed a few bows with TB3. It works real good. The only thing you are doing though is protecting the back of the bow. So there is no reason to put a lot of layers on. You will get no shrinkage using TB like you do with hide glue. I use a warm bowl of water with TB3 diluted in it. I then soak my prepared strands of sinew in the solution. I apply it to the bow, smooth it out and pat down the excess moisture. When I work the bubbles out I put TB3 on my fingers while I smooth it out, soaking it with more glue.
Like Justin said, it is not waterproof or IMO, not water resistant. I use it to put my stone points on with sinew. When I want to take them off I run warm water over them from the kitchen sink, a couple of wiggles and they pop loose, all slimey. I seal my bows with Spars Poly.
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I don't believe anyone is saying that TB won't work for applying sinew. And I don't believe anyone is disputing the knowledge and quality of any acomplished boweyers. Everyone has their preference for one reason or another, and this thread is about obtaining more information, If any of these acomplished boweyers would like to post their opinion, they are most welcome. I'm quite sure they would all agree that either glue would work, they would simply have different properties and results.
I haven't read any comments on here pertaining to the fact that they "know more".about it than anyone else does either. It is simply a debate in order to obtain more information, which is what this forum is supposed to be about. We are all free to read a different post if this one is agitating to anyone.I for one do not know everything about it, which is why I'm asking those who know more about it than I do. I simply asked if anyone could tell me the uses for TB, No-one said anything at all about Ed Scott or any other boweyer being wrong in their choices.
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Nothing against TB2 or 3 I have used both but i think it is useless for sinewing,You want to sinew something use hide glue.
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The world has progressed thus far from lazy men looking for an easier way to do things. I too am looking for that easy way, but i think in this case i will use the hide glue. If i could i would go spend the money and take a week long class from Ed Scott. that would be the bomb (as the kids say). But for now i will use the Hide glue. BTW, tite bond 3 is really awesome wood glue when used for its intended purpose. I use it when making the few furniture pieces i make, and have used it on hickory backed bows several times with no failures.
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It's been a tricky discussion on an other thread, seems like if one says 'no tightbondIII for sinewing' it's being equaled with 'Ed Scott is a foul' ...or denying the holocaust (just to exaggerate it a little...)
See, I REALLY like what I have seen in the Ed Scott Video, and yes if I had a chance to follow that guy into his workshop for whatever stretch of time, I would! ...BUT I simply DO NOT BELIEVE, Ed glued that little sheephorn bow this anything else than the best hideglue he could get, or that thing would come apart!
I'm sure everybody would accept people like Lukas Novotny, Jaap Koppedrayer and Adan Karpowicz (have you seen Adam's book??) as being in that same bowyer's league than Ed Scott. Last year I had the fantastic experience of participating and translating in a daylong lecture about hornbow making held by Lukas Novotny over here in Germany; we were only 4 or 5 people, we really talked detailed, we inspected and shot some 10 or more hornbows of various kinds, finished bows as well as bows with the sinew laying open! These bows were some of the best bowyer's work that I ever held in my hands!!!
The question of TBIII came up, too, and I cannot repeat Lukas' opinion on that here, since it's really not in the family friendly corner.
I do not have enough personal experience with laying sinew for a final conclusion on the matter, but I believe that TBIII works, if the sinew is meant to protect the back, if the plan is to pull that back into a serious reflex, it'll be hideglue, hideglue or hideglue you can use.
JMO.
PS: I used TBIII to seal a snakeskin backing. When it got wet from rain, the surface started reacting RIGHT AWAY. It didn't come off, but it reacted.
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I have made many bows using hide glue to sinew the bow. When I tried to sinew an osage bow in my shop in Alaska the bow literally tore itself apart as the sinew dried. At first i thought it was the wood, so I tried another stave with the same result. The next one I did I tried to slow the moisture loss down with tape on the belly less cracking but another stave ruined. I usually build about 10-20 bows a year and at least 4 will have sinew, I only build in the winter and the winter air in my shop is very dry. I tried the titebond 3 glue in desperation and had no checking or shakes form in the bows. I am very pleased with the results using tb3 however I usually over reflex the bow prior to sinewing because I do not think the method pretensions the back the way hide glue does, I also have strong feelings that the dependability of a selfbow is one of its main attributes, while performance falls further down the list. If you live in a very dry climate and are having the same troubles I had give tb3 a go. As far as laminating I think urac is a far better glue.
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I put the tt3 on after the hide glue and sinew was dry.Not while it was wet. :)
Pappy
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Pappy, or whoever, did you ever glue birch bark to a sinewed bow's back using TB3??
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Medicinewheel,I am verymuch interested in making asiatic hornbows,I wish I could have attended the lecture as i really admire Lukas's bows.Is there any chance of getting a transcript or coby of that lecture as I believe Lukas is tops in making hornbows.
Thanks
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I made a 49" hickory, edge grain board, with using Titebond 2 and dry sinew. 2 layers. Bow pulls 55# at 27#. Back looks pretty ugly though, although black paint hides it pretty well.
Dave
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I have a sinew backed bow(Knox gelatin) with birchbark applied with TB 3. It worked well. It generally doesn't require much to hold a protective backing on. Many glass bows have snakeskin applied with yellow carpenters glue. That probably isn't the most compatible glue with roughed up 'glass and Epoxy. It still works though.
I can try to find a picture of the bow if you want.
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@shikari:
No I'm sorry, no transcript of the lecture; but yes you are right Lukas is very good at making these bows!
@Pat:
Yes I thought it would work, too; I seem to remember I heard of snakeskins applied to FG backs with carpenter's glue.
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Here's a new wrinkle. I've got a sinew backed osage bow I built probably 8 years ago. The sinew was applied with hide glue, and finished with Thunderbird epoxy. Every time I draw the bow I get a cracking sound, :o and it has developed cracks across the sinew or the finish mostly, and the Thunderbird has lifted in some areas.. I have been thinking of a way to fix this one, but I think because of the epoxy I will be forced to strip it down and redo it. Any one got any ideas?
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Sounds like a redo to me Dano,, don't see how you could ever seperate the epoxy from the sinew.probably a lot less frustration in the long run to just redo it.
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Dano, spray it with nitrogen and the epoxy will pop right off. I have a can carpet restorers use to freeze chewing gum to get it out of the carpet.
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That's a thought Eddie, That would be better on the bow. I was going to try heat, and try to loosen up the hide glue.
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Hi,
I am a flute maker...have attempted bows and so far manage to blow them all up! I used to glue my Native American style flutes with Gorilla Glue (Lordy what a mess!!) until Fine Woodworking did a test on all the water proof glues (flutes have to be glued with a waterproof glue as when they are played they get a ton of moisture from the breath into the flute). FWW found that TB 3 beat all the other glues in their test. I have had zero problems with TB3 other than when sanding on a large belt sander I have to watch heat build up and keep the wood moving around glued areas. I do use a wipe on satin poly inside and outside for finish on my flutes...so you could say the TB3 has extra protection. Hope that helps...interesting topic. This web site is really teaching me (an old geezer) alot.
Thanks,
Rand
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I'm gonna use hide glue on my sinew. But i am not throwing out my TB3. One other thing i use it for is sealing the ends of staves. Works great for that, haven't had a check since i started using it.
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I made my first osage recurve sinewed backed bow last winter. I pretillered it due to the learning experience. It was 40# unbacked at 28". Then I applied 4 layers of sinew using watered down TTB3 and let it sit in reflex for one month. It completely dried out and the bow gained 4 # right immediately. Later in the winter as the house got dryer it shot up to over 55# of draw wieght. This summer my son used it for 3d shoots and I could tell it was more sluggish with the humidity in the air. We put it on the tiller tree and checked and it read 49#. I am hoping as the winter sets in this year it will rise in draw wieght. It works fine but it is still suseptable to the changes in the RH from what I can tell.
Dano, maybe it would be easier to sand the Thunderbird off and reseal?
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Chris, it's too late ;D I have the sinew off and I am retillering the bow as we speak. Strike one for Thunderbird!!
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Chris, it's too late ;D I have the sinew off and I am retillering the bow as we speak. Strike one for Thunderbird!!
Share the knowledge Dano. Did it come off with Eddies idea?
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I thought I would just try scraping it off, so I started at the handle with a sharp chisel once I got under the first layer of sinew it came right up, had to do a little fine scraping with the cabinet scraper, but no real problem. Not real impressed with the hold hide glue had on the wood, guess that's why old furniture falls apart at the glue joints.
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FELLAS ILL LET YA IN ON A SECERAT I LOVE THE HIDE GLUE BUT JUST ANY OL HIDE GLUE DONT FLOAT MY BOAT IV FOUND NOTHING IS BETTER N THE GOOD OL PIANO MAKERS HIDE GLUE # 1 GRADE IT IS THE STRONGEST AND PUREST HIDE GLUE YOU CAN GET DANO THINKIN ABOUT THIS CRACKIN IM RELLEY WONDERIN YOU RECALL IF THAT SINEW AWAS A LIL GREASEY ? BACK THEN IV HAD SOME PLMS WITH STUFF THATS JUST A BIT GREASEY SEEMS AFTER A PERIOD OF TIME THE DARN STUFF GIVES OUT JUST A THOUGHT CUZ I NEVER HAD A PM WITH THE THUNDERBIRD BROCK
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Brock, I don't remember it being too greasy. It could have been the osage itself. Even now this bow is kinda oily, it's a piece I got from Roger Sparks, it's real red osage. I'm thinkin I didn't degrease the back well enough before laying down the sinew.
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could very well be dano good luck on fixin that one ha hope to see you and sal and all at ojam boys say tell ya hi brock
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Thanks Brock, right back at ya's.
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"It shrinks?" "Like a frightened turtle!"
sorry, couldn't resist >:D
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Wow just read through most of this thread. Some different view points to say the least,,,,,Guess I'll just go ahead and throw in another rock in the pond. I am I the only one still making my own glue? I just the the sinew scraps and trimmings and throw them in the crock pot with some water over night and by morning Good pure sinew glue. Use what I need, put the rest in an old butter dish and throw it in the freezer till the next bow is ready When I first started doing it I was concerned because it didn't feel super sticky but I after testing was a believer. It's rips the wood before letting go. As far as waterproofing I agree with Justin it is what the finish is all about.
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keenan, what a about using rawhide dog bones?? cut up into small pieces and boiled down. the reason i ask is i have used that to back a few bows, which was tricky. I used warm water to soften em up to straighten out and when i took them out of the water man they were tacky. seems that cowhide isn't much different from other hides. what you think???
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Should work fine . I've never tried those but should work . Give it a try on a small peice and post the results ;)
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I've tried the dog chews. They work to an extent, but they don't yeild much. I think most of the protiens are leached out during processing. I have a large coffee can full of hide glue sticks I made from deer hide. I'm sticking to that, it's never let me down yet.