I've been sorting through my Yew and taking the dodgy sapwood off where necessary and generally looking at what I have. Mostly it's short lengths and the few long bits are bent sideways.
As it happened, Rob a mate of mine had his bow blow up on him, he'd spent ages making it and it looked fine on the tiller, these things happen and it's a small crumb of comfort that he was videoing it at the time. Just before it explodes, you can see the lower limb bending a tad more than the upper, but not alarmingly so. Tiller can change as a bow gets shot in and areas can suddenly appear weak.
I've just found the same thing on my flight bow, where the upper limb suddenly looks weak. Fortunately I'd left it a few pounds over weight and spotted it early. I'd been shooting a few arrows through it at a short draw. I've given it a light rasp and scrape on the lower limb and I think it's just about the right weight now at the 26.25" draw length to suit the flight arrows I've made for testing.
Anyhow Rob asked if I could make a bow for him and I said I'd see what I had in my stash. He's happy to go for Boo backed Yew which will be interesting as I've not done a heavy Warbow like that. (although I did the 120# boo/Yew primitive in January). Boo/Yew is a great combo and the boo is hard wearing too, it can withstand a knock which would put a serious dent in Yew sapwood.
I was expect it to be easy... rip the dodgy sapwood off a stave and get on with it. Ah! When I looked at the staves, one was too short, and the long one had a big sideways bend. I tried to lay out two straight limbs on the bent one, with some degree of success, so I sawed it in half and roughed out two billets on the bandsaw. One limb was still a tad curved sideways and they both had some sapwood showing on one edge. Hmmmm.
To hedge my bets I cut another billet from the short stave, even that was tricky trying to pick the best portion of the stave. So, I've ended up with 3 billets, but after all that I've chosen the two from the original stave! It's taken a lot of fiddling and trimming to lay out two decent billets, but the big advantage is the bamboo backing, which will, being a continuous piece, will support the splice and mean that the splice only has to withstand compression and can thus be rather short, say a 3" Z splice. This buys me a little more length and by putting the splice just below the centre line I can get away with one longer billet and one a little shorter, which is how they happened to turn out. This still gives an 80" bow which will give some wriggle room.
What was, in theory, a simple job turned out a lot more complicated, but like most jobs, the more trouble and preparation that's done early on, pays dividends later. In getting the billets clean and square, hopefully the splice will cut better and fit together without too much trouble. Actually that's another advantage of a shorter splice, it's a bit easier to fettle to get a good fit. In fact, I'd bet good money that with a boo backing you could just butt up two billets and it would work! Of course you'd never try this as any slight bend the wrong way (say when it's lobbed into the back of a car) would just pop open a butt joint.
Anyhow, I'll possibly saw the splices and get 'em glued tonight, cup of tea first!
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