Sinew question

[PatM]

  OK but would you consider those  a success due to your previous research?
  I guess how we measure success varies.

 If you are happy with your workmanship and are comfortable with your knowledge, that's all that matters.

[gfugal]

  OK but would you consider those  a success due to your previous research?
  I guess how we measure success varies.

 If you are happy with your workmanship and are comfortable with your knowledge, that's all that matters.

I am proud that I was able to get bends like that without horn. Not a lot have people have done that on here. That’s not to say that I think they are the most well-designed bows or the fastest, but they are bows. I didn’t pick those designs because of my research, rather it was out of necessity of material, and not knowing any better. So if anything, more research would have inspired me to do a different design. I guess I don’t know what thing I said is contrary to what others have shown through experience. But I would agree I need more of it.

So just get going on a slightly longer bow with siyahs. I posted a picture of exactly what you are looking for.  You may be overanalyzing things now.

That’s good advice. I don't want to seem like I'm trying to contradict you. I will attempt it soon. I remember that picture and I thought it was sweet. Thanks.

Ed that looks like a super model setting in that chair  Bow porn....lol nice pic I know I have over thinked stuff in the past but have under thought & paid the price too ,while where on this topic does any body have a preference for a certain sinew preferance elk,moose,horse,white tail etc ?

Haha that’s what I thought. It looks like its in the middle of some abandoned wherehouse with a spotlight on it. Is that your work shed? But it’s a sick bow. Hopefully you will get a good force curve out of it.

gfugal......On your other bow the polyester cable you put on underneath while probably in your mind gave you some sort of security or poundage hike actually I think took set and did not come back as sinew will.Best to leave synthetics out of the equation and just go with sinew alone.
Linen string backed bows will take set too just like wood.Any fibrous type back will but it can increase poundage and make them practically unbreakable.

I got set even before I added the cable. Here’s a picture of it before the cable and second layer of sinew. I agree with you that it's going to stress the belly more, I just don’t think that rules out the use of cables on wood bows. You don’t have to put it under the sinew. It was just a unique Idea I had, but I believe it would perform better if it wasn’t glued in place and was allowed to return back to its original shape. Don’t base a cables effect from my bow. It was going to get set no matter what because of the overdraw. I’ll have to experiment with a longer bow. You also mention that fibers, whether synthetic or not, get set? I wonder if that set is just the re-positioning the fibers after its stretched out for the first time, or if its because it's stretched past its yield point. It was mentioned some time past on here that flax gets stiffer the further it's stretched and doesn’t behave like a spring in hooks law. I’ll have to look more into that.

[PatM]

You may be tricking yourself a bit by  measuring success by a lot of bend and not breaking(right away). Definitely few people want to go for extreme bends in wood for various reasons but backed wood can hold together under ridiculous bends.  Especially less compression resistant woods and light draw weight.
  That doesn't make it a viable bow though.

[gfugal]

You may be tricking yourself a bit by  measuring success by a lot of bend and not breaking(right away). Definitely few people want to go for extreme bends in wood for various reasons but backed wood can hold together under ridiculous bends.  Especially less compression resistant woods and light draw weight.
  That doesn't make it a viable bow though.

I don't think you can judge success off of one factor alone. Is how far a bow can bend determine success? No. it doesn't but I think it is a factor, along with aesthetics, stability, durability, speed etc. I think the best factor is the speed it can shoot an arrow. these bows weren't the fastest so does that mean they weren't successful. Maybe, but they still teach us things, especially with a topic about sinew. So take them for what they are. I'm not going to be ashamed of them.

[willie]

I wonder if that set is just the re-positioning the fibers after its stretched out for the first time, or if its because it's stretched past its yield point

possibly both, and there is also creep, a third property of fiber to consider.

ht      tp://samsonrope.com/Pages/DemystifyingElongationandCreep.aspx



traditional cable bow archers had twisting levers to make adjustments

https://www.archerylibrary.com/books/mason/north-american-bows-arrows-and-quivers/docs/lxxv.html

[BowEd]

I have nothing against cable backed bows.In realize they are out there.The polyester cable did not return the bow to it's original form though because it took set is my point.Along with the fact that fibrous material does not return like sinew in a matrix of hide glue on the back of a bow.I doubt very much it would of returned the bow to it's original form on top or underneath sinew.Nice experiment though.You learned something.

[PatM]

The old pre-stretched silk backings did in fact function like sinew. That was through some skillful manipulation of the fibers and the binding glue.

 The beauty of sinew and hide glue is that it does almost all of the technical work for you.

[BowEd]

I did'nt know that about silk.I've never researched any about it I guess to begin with or really considered it.I was thinking vegetation type material at the time I guess.That'll teach me to never say never.Silk is fibrous but from a worm.Sinew is fibrous but from a deer and the like.

[willie]

Pat, just curious if you know whether the silk application was done in single or multiple layers?

[PatM]

I'll find some of the details. It was a single pre-fabbed strip that was applied in one go. Not sure how the strip was first laid up though.

 But it definitely countered Tim Baker's thoughts on silk.
 
 This is mostly because you have to consider fibers and their binding matrix together.  People love to say carbon is really stiff for example. But it isn't until you saturate it with epoxy and cure it.

  Here is the link to the patent:    http://w ww.freepatentsonline.com/2285031.html

[willie]

each strand is pretensioned in the matrix


from the patent description....

When the sheet is manufactured the strands are placed on the drum under tension and after drying they will remain under a pretension of at least one half inch in a yard (36 ins.), the strands being so held by the glue as to give. this effect. Such a sheet when applied to a bow, even without additional tension is much superior to other forms of backing material.

[PatM]

I know, I said that before I located the link and checked. 

 There is a popular mechanics article from the era showing how the strips were tensioned and applied.

[willie]

the drawings are in a pdf that you can download at the url you linked.

the filaments were continuously and individually prestretched before manufacture into a backing, and this can add up to an amount incredible of stored force in the matrix. The cured backing was technically  post-stretched before gluing to the back.

not quibbling about the use of words here, only making clear that the fiber was actually stretched three times (if you consider the bow at full draw.)