Thursday, 17 February 2011

Full Brace Height

The 60lb Yew bow is coming along, I've been taking some off the belly with a spokeshave. I stretched a line from tip to tip to true up the straightness now it's been flexed a bit.
I've now got it back to about full brace height (6" judged with my fist and upturned thumb, a recognised 'rule of thumb' the 'fistimelle').

60lb now gets it back to about 22" and the shape is a bit better. My bit of heat bending has eased off that bit of deflex.
One tip of the bow is trying to twist slightly and bend off to one side, it's a matter of easing off the stiffer edge for the last 6" of limb and keeping an eye on it, the sap/heartwood boudary is slightly angled at that end.
A bit of twist isn't an issue as it will settle to it's final state as the bow is tillered and drawn a few hundred times (it gets flexed about 20 times on the tiller to it's full 60 pounds at each testing), it's just a matter of avoiding any sideways bend which could suddenly get worse.
As the draw weight is reduced the thickness will decrease, this will make it easier for the bow to bend back rather than sideways, so it should all be ok. Tillering is about trying to stop things going wrong before they happen, and coaxing the stave into becoming a bow.
Comparing with the previous post you can see the tips of the bow are coming back about another brick.

I've had it up on the tiller again and the slight twist is looking much better , the right limb is doing a bit more too and it's now back to 23" at 60 pounds.

As spring and spring cleaning is in the air I've decided to patch up the 'up and over' garage door which has some how got some holes in it (whoops!). The paint is also coming off too where arrows have struck and flexed the metal as well as making holes. I've filled the tiny holes and I'll give it a lick of paint tomorrow.
I've got some big foam blocks (rescued from the council tip) which I shoot into now, so hopefully the door will be safe.

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