Primitive Archer
Main Discussion Area => Bows => Topic started by: stuckinthemud on February 20, 2020, 01:39:43 pm
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OK, so, if I have a bow that already has all the reflex I want, could I draw it straight, then add the sinew, then let it relax into its original reflex to cure? Would this have the same effect as adding sinew to a straight bow then pulling it into reflex to cure?
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Not quite.
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Fair enough, why? If I take a suitably long time to relax the bow back into its reflex, how is that different from winding reflex into a straight bow as it cures?
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It seems to me you want the wood and the sinew in tension. With your scenario you would be relaxing the tension in the wood, although the sinew should be at the same level of tension. That is just how I imagine it in my mind. Best thing to do would be try it and see what happens.
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i would just add the sinew,, depending on the wood,, it might add some reflex ,,, when you tiller it ,,,, it will pull some of that out, and you will end up about where the stave started,,
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I think You are on the right way. If You sinew back already reflexed bow You will have too much reflex for a wooden bow. No matter that part of reflex pulls out. The out pulled sinew is already under the tension too early . If Your bow is not made from osage, yew or juniper, I wouldn't sinew back this bow under the existing reflex. I would do it exactly like You intended but i would live some reflex, I wouldn't make the bow completely straight :)....
I forgot to mention lilac :D
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alot depends on how much sinew you put as well,,
a thin layer probably not gonna induce much reflex,,
the thicker the layer the more likely to induce reflex,, and its hard to measure that,,
I stick with my original suggestion,,
put a medium layer of sinew and go with it as is,, pulling the natural reflex out of the bow to put sinew on,, seems counter productive,, it would work,, but you are likely just reducing the performance of the bow,,
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pulling the natural reflex out of the bow to put sinew on,, seems counter productive
Why the bow should lose natural reflex if to straighten it for a short time for sinewing. Its like stringing the bow. As the sinew drys he will set free the clamps and the natural reflex will return. He won't heat or steam the bow. I think.... :).
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ok I guess I dont understand,,
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ok I guess I dont understand,,
That's because of my English is bad :).
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It's just much more sensible to reflex the bow a bit and then add the sinew and then add a touch more and wind it tighter as it cures.
No reason to complicate things.
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How much reflex You have naturally?
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It's just much more sensible to reflex the bow a bit and then add the sinew and then add a touch more and wind it tighter as it cures.
No reason to complicate things.
It already is reflexed a bit.
I guess the question is more like how much reflex can a wooden bow have before the belly starts to break down and you get no net advantage.
Answer a couple inches max. Anymore (other than with a very short drawlength) and you will simply get squashed belly cells leading to much lower compression resistance. Once this has gone you've got a sluggish bow that you put lots of work into.
As Maitius says yew/juniper/osage and perhaps a few others can handle the reflex. but most woods can't. Remember that 1% extension or compression :) You simply can't get around that fact.
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The bow is naturally reflexed and is already tricky to string. I'm not going to heat treat or steam unless I have to straighten it before I sinew it. I really don't want to end up with more reflex but I am going to put on a pretty thick layer of sinew - I've stripped most of the sapwood off a short and challenging yew stave I would have otherwise burned so its a great practice piece as there's no loss if everything goes pear-shaped, but its going to be interesting to see how a sinew backed yew heartwood bow performs, if it holds together.....
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I’m not sure I understand. If you “temporarily “ Straighten bow to apply sinew like stringing a bow. It seems to me the sinew would do nothing but add weight after you let stave return to its natural reflex state. The sinew would all be loose and not in tension. I’m not sure I’m understanding question though.
I’ve never done a sinew backed bow either but many I’ve seen done were intensionally slightly reverse stung to add a bit off reflex and tension for the sinew. As the sinew dried it pulled a bit more reflex and tension on the sinew. I’m thinking this would allow better performance from your sinew.
Bjrogg
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So, I have 4 inches of natural reflex. If I did like normal and reverse string the bow as the sinew cures then I could have 5 inches or more of reflex. If I clamp the bow down to 1 inch reflex and sinew it then I could slowly wind out the clamps and let the bow go back to its 4 inches reflex, the sinew would still be compressed into the bow but tbe bow will not gain any extra reflex
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It won't be "compressed" it will just be moved like a pushed rope.
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Remember that 1% extension or compression :) You simply can't get around that fact.
The point of the sinew is to get around that fact.
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Have you considered using rawhide?Using a primitive stringer to string the bow works well.
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It won't be "compressed" it will just be moved like a pushed rope.
I thought that you waited a while for the glue to gel, then wound in the reflex so that the sinew would not be able to slide around?
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Would it be possible to add deflex at the handle? It's probably too late at this point, and I don't know what sort of handle you have...just a thought. Using a stringer like Ed mentions may be the best bet.
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It won't be "compressed" it will just be moved like a pushed rope.
I thought that you waited a while for the glue to gel, then wound in the reflex so that the sinew would not be able to slide around?
That's the thought but gelled sinew doesn't have any linear compression resistance.
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you dont have to reverse brace to put sinew,, just put it on there,, and you will end up after tillering and shoot in,, with about 3 reflex,,maybe 2 depending on your draw and poundage,,and how much you put on,,
if you put 500 grains,, I would say 2 inches,, if you put 1000 ,, maybe 4,,, no need to reverse reflex,,
or the other thing you are talking about,,
if you want to deflex the bow to put the sinew,, it wont hurt anything,, but wont accomplish anything either,,
if you are worried about too much reflex,, just heat the bow and bend it out,, I will say in my experience ,, making sinew bows for about 30 years,, the ones with no reflex will shoot well and smooth and kill a deer,, but the ones that hold some reflex will perform better and shoot harder,, sinew bows are a different animal,, the stretch of the sinew acutally puts less pressure on the belly,, of course past a certain point it could crush the belly and need horn ,,
but moderate reflex is not gonna crush the belly,, 2 inches is definitely not pushing the limit at all,,
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My logic says that if You lay sinew onto the straight bow or onto the reflexed bow which is pulled to straight, the sinew will dry and shrink exactly the same way and You need exactly the same force to stretch this sinew. You can look on that like this: You will dry two similar bundles of sinew separately from the bow somewhere on the plastic for example. After drying these two bundles are completely similar. Now You glue one of them onto the straight bow. In this case You must pull the straight bow into the reflex and the bow limb will work against the sinew, so the limb is pulling the the sinew back instead of You :). The other bundle You will glue onto the reflexed bow and there is no need to pull the bow to reflex because the reflex already exist and bow limb will work with sinew together in same direction. In last case the limb will not help You to pull sinew and You must use more force to pull the reflex of the wood and the reflex of the sinew.
To back the bow which is prereflexed with sinew, pulling it staight before laying the sinew, seems to be a good idea. It gives more draw weight and is faster for sure. Sorry for stealing but I will make my next bow exactly in this way :).
Sorry for horrible use of English :D....
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sinew is not logical sometimes,, :) more draw weight does not always translate into better performance,
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sinew is not logical sometimes,, :)
Yes I know that :). If to look how the juniper bow will bend after adding a sinew backing, then its really not logical, its magical :)...
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yes magical for sure,, :)