Main Discussion Area > HowTo's and Build-a-longs
Winter project - Yew Recurve bow
StanM:
Great project, Gordon. Beautiful work as always, and the information in this thread is invaluable. Much to be learned. Thanks for taking the time to post.
Bryce:
gordon dont be modest this thing is gonna be a missile shooter 8)
Jude:
Can't believe I missed this until today! Great build-along Gordon; got me wanting to order up a yew stave now.
From what I understand on sinew, considering a yew bow with a thin sapwood layer needs none, is that the sinew is even more stretchy than the sapwood, and so will take some of the compression off the belly and helping the bow to retain more reflex. This point has already been mentioned in the thread. Another point mentioned, is that sinew is heavier than wood. Removing all the sapwood and filling the gap with extra courses of sinew would place some of the sinew well below the working plane, where it wouldn't be doing much work. It would also raise the mass of the limbs, robbing them of performance. I'm not sure what it might be, but there must be an optimum thickness for sinew on yew, that you could use regardless of the presence of sapwood. If it is truly necessary to remove the sapwood due to delamination issues, it would make more sense to make up the thickness with more heartwood, rather than more sinew. I honestly don't see much difference between two and a half courses or three courses.
Gordon:
Even three courses of sinew is a pretty thin when cured (relative to sapwood) so I think it is probably all working. I don't honestly know if I opened myself up to delaminations issues by keeping a thin layer of sapwood. The curing sinew has definitely pulled the bow into a more reflexed shape and I don't see any evidence of a problem yet. I expect I will find out this weekend when I tiller it. Performance wise, there probably isn't much difference between 2 1/2 courses and 3. I did it this way because I wanted to create a bit more of a crown on the back which made smoothing the sinew surface somewhat easier.
Gordon:
I’ve let the sinew backing cure for a couple of weeks and it is looking good. So today I am going to tiller the bow. The bow feels a little heavy so I take about 20 even scraps off of each limb using a card scraper. It’s now ready to be braced for the first time.
For the first brace I like to keep the brace height fairly low. I don’t want to unnecessarily stress the limbs in case the tiller is off. The lower limb is a bit strong, and one of the tips is slightly out of alignment – not bad for the first brace.
I fix the alignment problem by clamping the bow in my vice and gently heating the problem area while hanging some weights off of the tip. You don’t want to get the limb too hot or you may end up with a delamination. I keep the heat gun on the lowest setting and sweep it evenly across the belly from a safe distance. This ensures that the core will heat gradually and settle into the desired position. When I am done, I let the bow cool for about one hour before I string the bow again. I got lucky and the procedure worked as intended – the tips align perfectly.
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