Friday, 27 April 2012

Devil's Thumb Print

Ok, it's a fanciful title.
The stave I've just started on was cut close to a knot, and it turned out to be more extensive than I'd hoped, there are also some streaks of dark discolouration emanating from it which are of some concern.
Most of it has slowly disappeared, but it took several iterations of tweaking the centreline to minimise it. The pictures on the left show it when first roughed out, the pic on the right shows what's left of the 'thumb print' now, which is pretty much how it will remain.
Elsewhere on the stave there is some of the nice reddish purple colour which seemed sound enough on the 90# bow I built in January. I've made really rapid progress on the bow and it's currently to a low brace height and pulling back to 55# at about 20" (target is 60# at 28") .
There is still a long way to go as I need to carefully work over the back and I may reduce the length by and inch as it's for a guy who is 5'9" so I think 70 - 71" should look about right.
It's easier to make a longer bow as it's lower stressed, but I want it to look right, he wants it to shoot 180yards, which should be fine, but a shorter punchy bow with less inertia in the limbs may be faster.
The stave has a lovely hint of natural reflex at one end (that will be the top limb) and a hint of deflex on the other. Lopping off an extra inch will take out some of that deflex.
We are back to that thorny old question of the lower limb being tillered stiffer than the upper. Robert Hardy once told me one of my bows was upside down because the lower limb looked weak! I didn't actually argue but I showed him the natural deflex in the lower limb. If one is reflexed and one slightly deflexed which way up would you make it and why? Personally I'll stick to putting any deflex at the bottom, I've toyed with different ways of doing it and ended up thinking the tiller didn't look quite right at full draw.
Each to his own and if it ain't bust, don't fix it.
People often ask how long it takes to make a bow. I've put in two good days on this one and could probably have it shooting by tonight, but I won't do that as I'd be rushing and increasing the chances of it breaking. It would still need  the horn nocks, arrow plate and grip fitting and the careful finishing. The shooting in and final tweaking takes time too.
So it's one of those questions I try to avoid, but when pressed I generally reckon about 50 hours as I'm trying to get the best of the stave rather than just making a working bow as fast as possible. What is easy to forget is the time obtaining and splitting the wood out of the log and all the time I've spent musing over where to get the bow out of the stave.
There was a questionaire on a website that someone was doing as a school project, they asked:- How long does it take to mark out a bow? Well to mark out where you will saw a bow from a stave takes about 5 minutes, but the thinking can take a few months of consideration!

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