sinew scenario

[upstatenybowyer]

Let's say you rough out a 56" yew stave (sapwood removed) apply a thin sinew backing, wait for 6 weeks for it to cure, tiller the bow (it bends through the handle) to 27" and it ends up with 10 pounds less draw weight than you hoped for. If you were willing to wait another 6 weeks, would it make sense to apply another 2 layers of sinew? If so, do you just size the back over the pre-existing sinew layer and add more layers?

[Stick Bender]

I'm no exspert but I know some guys add 1 layer at a time I don't see any problem doing it like that ,it's been suggested to me to do it like that when I came in light on a bow , the one I'm working on now I'm going to pull more reflex in the bow after the glue gels putting the belly into negitive compretion and the sinew into a Perry reflex which will add more weight in theory ,never did it but going to try it , my understanding is you can add sinew at any time that's sounds like a nice combo Yew/sinew.

[PatM]

You can add sinew any time. Just need to re-activate the glue. If you've handled the bow a lot you should clean the back off before laying down more sinew.

You can wash it and then size the still damp surface and sinew away.

 Lots of debate as to how much weight gain you will get and how productive it will be.

 
  How much reflex you can bend backwards while you sinew may also be  an iffy thing after already drawing the bow to 27".

[upstatenybowyer]

It's still holding a little over an inch of reflex after tillering to 27" I thought I'd add another inch or so on round 2.

[bradsmith2010]

in theory seems like you could add the sinew and get weight and performance,,
the few times I tried to add sinew to a bow already being shot,, it did and will add draw weight ,, but the performance was not that good,, or as good as other sinew bows I made,,  that were only  tillered or tillered to half or no tillereing  before putting the sinew on,, sometimes I will tiller the bow backwards and put the sinew on,, and it has not been floor tillered at all,,

[Stick Bender]

Hey Brad I know you do a lot of sinew bows  if you get a chance could you exsplane how you go about tillering a bow back wards with sinew ?  I'm glad you mentioned about adding sinew to a already tillered bow  wasn't  as efficient That was something I didn't  know .

[Bryce]

Patm is right you can add sinew at anytime.

Too much sinew can actually be too much of a good thing.
I would chalk it up to experience and start another.

The way I do it is: I have a 27" draw. I will tiller the bow to 20" then reverse brace a few inches, add the sinew, and then when the sinew is good and dry I will finish the tillering, put it through its paces and call it a bow.

[Danzn Bar]

I'm with ya Bryce ............. that sounds very close to what I'd do.....
DBar

[mikekeswick]

You can get away with it on a wood bow if you sand then wet your backing. However what isn't good is that the belly has already been compressed. To get the most out of sinew you should draw it into more reflex both before you add sinew and once the layer has gelled (to put it into compression as it dries). wood that has already been compressed doesn't like being stretched. Personally I wouldn't bother, I would start again. Sinew has low stretch resistance so you will need to add quite a bit, lots of shredding for a less than stellar outcome.