Primitive Archer
Main Discussion Area => Bows => Topic started by: Del the cat on October 09, 2010, 01:01:35 pm
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My Ash Meare Heath bow seems to have suddenly shifted, having been shot in a bit (probably only a hundred arrows) the lower limb seems to have developed a tighter bend just below the fade. It's not a hinge as such, but I don't like it.
I've re-tillered the bow slightly but I've lost about 8pounds draw weight in the process!
There's no sign of damage or set or chrysalling or anything untoward, just this odd shift.
Have any of you guys met this before???
Del
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Yes, I have. Do you exercise the stave between wood removal sessions? Was it dry? Jawge
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I have learned that I should shoot a bow in (at least 100 arrows) before I determine which limb is the bottom. Tiller sometimes shifts.
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Cheers guys, that's reassuring.
Yes the wood was well seasoned and had been tillered slow and steady, but I don't do a lot of deliberate exercising as I go.
I must admit I almost felt physically sick when I saw it, I've never really had much change of tiller before, and to be honest I thought 'shooting in' was a bit of horse feathers.
It's good to know we are always learning.
it will be a challenge for me to make something useful out of it.
Thanks again guys, it's great to know I'm not going mad ;D... I've written it up on my blog as I like to be admit to my mistakes and it hopefull will make everyone else who makes a 'wrong un' feel a bit better.
Nature has a way of stopping us getting big headed.
Del
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Some times it's nothing we do.There's no set form.Remmber wood is wood.
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Del, it could be the wood is registering the wood removal. When I went to a rope and pulley it made it easier to exercise the stave to and there were fewer surprises. 20-30 pulls at very short draws will do it. Jawge
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Del the Cat,
I'm afraid I don't have a solution or prevention method to share with you, but I can at least say I have shared in your pain and disappointment. I have a nearly finished lemonwood bow on the shelf that suddenly bent significantly about 3/4 down the lower limb while tillering. At the slow, careful rate that I was removing material, I refuse to believe it was because I removed too much in that spot. It just happened. Unfortunately, it also took on a memory and no amount of re-tillering would help. I re-tillered it until I ended up with a very light draw weight and then tried to back the bow with another strip of wood. That didn't work either; the bend still came back.
Similarly, I have a short bow-in-progress on my workbench right now from a scrap board of purple heart that a friend gave me, that began to bend inexplicably as I cut out the rough bow shape with a saw. I haven't even got to the floor tillering stage yet. I can only suppose that there must have been some residual stress in the stave itself that was suddenly released when some wood was removed. I hope that I can bring it back with heat treating/bending.
I don't know if heat treating your bow might remove the memory in that area or not, but if you try it, I'd be very interested in seeing you post the results.
Regards,
Story Teller
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Sometimes small tiller changes can occure when shooting in a new bow, especially if weather conditions change, especially RH. As mentioned, exercise the limbs plenty between removing wood, and the surprises should be minimal. Make sure your wood's MC is stable before begnning, also, to minimize drastic changes.
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I havn't looked at it this morning, but I'm probably goin to completely rework it a bit shorter.
I've not seriously played with heat treatment as heatguns don't seem very controllable to me and (being honest) I'm a tad sceptical, but maybe this is a good one to try it out on?
Does Ash respond well to heat treatment? (I'll probably persuade Santa to get me TBB4)
Del
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Del cat, I have recently experienced the same with a lam bow I built. I just meant to remove just enough to equal the limbs, when the darn thing hinged, at the reflex area.The sad thing is it shot great and true,but I just had to twik the upper limb. Well enough said ! Sometimes it is best to leave well enough alone. I did this another time and saved the bow with heat and reintroduced more reflex at that limb. I used a heat gun and simply bent it in a vise. I let cool an hour, then restrung and hit the mark.Don't always work it is wood we work with.lol Denny
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unlucky del , i thought your meare heath bow was a beauty too.hope the tweakiing works on it.john