Wednesday 22 February 2017

Emily's Return and Musing on Tillering.

Emily the cat came back last night after 3 nights missing, she's moving slow with a bit of a limp but seems ok, and very pleased to be home. We'll take her to the vet for a check up.

In the interests of fairness, putting the alternative view and generally trying to learn, here is some discussion of methods.
A guy (Will) on one of the sites has suggested that you can make Yew bows to virtually final dimensions including horn nocks before getting it on the tiller for final tweaking. I'd agree that this is possible with laminates and may be possible with a clean stave. He suggests that one advantage is that the wood doesn't get overstressed by excessive force when unevenly tillered and it doesn't even need a long string.
The interesting thing is that when you study the detail of what he says it is virtually the same as what I say and do, other than working on the tips and outers which come round later!
Here's his quote:-

"The long string is a bit of a controversial one as well - many bowyers who make superb heavy bows don't use long strings, especially not for a 100lb bow.  Something that light can be floor / vice tillered to begin with, then braced as soon as possible.  

If you watch Ian Sturgess' recent video you can see the process clearly.  It's a case of ensuring perfect tapers and watching the mass, getting the bow virtually finished before it even sees the tillering tree.  This minimises set, and drastically reduces the strain put on a bow early on, while many other bow makers drag it down on a long string to see where the problems are - by which point those problems have already damaged the bow.

However, all of that said, with unknown woods and unfamiliar draw weights a long string does keep things safe, at the risk of having a lower performing bow.  I think for what you're doing (at this stage just trying to make the thing work!) a long string is wise, but perhaps only to brace height.  Provided the bow is fairly even at brace height, you should be able to see almost all the problems with the tiller from the full brace shape."

Anyhow, it's given me thought to question my techniques and my position that "you can't make a bow by numbers" I think the key reasons for my approach are to cope with uneven staves, problems of bows trying to bend sideways and trying to hit an exact draw weight.
I think any technique done well souldn't overstress the wood, but I'd suggest that unless you have perfect timber, caution and proceeding slowly is safest.

He raises some interesting questions about how the medieval bowyers would have worked suggesting they couldn't take too long on the tiller.
This has been raised before and the counterargument is that they also couldn't spend ages measuring dimension and mass.
My thought was maybe they had a set of gauges to judge the key dimensions, but no such tools have been found. More likely we probably just underestimate their skill and they were good enough to get it all very close by eye and maybe flexing it by shoving it between two beams and heaving on it one limb at a time.
We simply don't know.
Anyhow, I could make a bow close to final dimension and go from there if I wanted, inded I have done so before. I think the key point is I try to explain the best way to do it to achieve success (especially for the less experienced) which is generally considered to be a well tillered bow at the target draw weight and length. I don't suppose the medieval bowyer of warbows was aiming at a specific poundage other than bllody heavy or over!

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