Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: wood carver 2 on March 30, 2016, 06:09:00 PM
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The other day I screwed up during a glue up of a tri-lam longbow. I had to remove the clamps from one limb to re-adjust a belly lam that had slipped. I put all the clamps back on, but for some reason I didn't tighten up the one that induced the reflex/deflex into the limb.
So now I have a nice longbow with one limb a bit curvier than the other.
It's not too noticeable just looking at the bow, but it becomes more so when I draw it during tillering. It looks as though it bends more at one fade than the other because the one has a bit more deflex to it.
Any ideas as to getting an even tiller in this bow? I'd really like to finish this one.
Dave.
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If it shows an odd profile unbraced, its limbs probably should NOT show mirror bends, OR, an even tiller at brace... but it's hard to say without seeing it in action on the tree.
The failsafe... regardless of profile, is to ignore predetermined tiller measurements, mimic your hold on the bow, pull the string from exactly where you'll pull it when shooting, and adjust the relative limb strength so that the arrow nock, or string hand fulcrum, comes straight down perpendicular to the handle/shelf. A line should be drawn on the wall behind the tree to propose this 'perfect travel'. This ensures the limbs are timed, flexing the same amount, regardless of what they look like... and this would ensure, despite its irregularities, that it was still a relatively efficient bow that was friendly to both the arrow and archer.
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Give it a shot and see how it works out.
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To prevent the lams from slipping try this. Drill 2, 1/8" holes across the handle area and the lams and use bamboo skewers as alignment pins. They will prevent the lams from slipping during glue up and while curing.
(http://i5.photobucket.com/albums/y199/PatBNC/lemonwoodALB008_zpsfbdc939f.jpg) (http://s5.photobucket.com/user/PatBNC/media/lemonwoodALB008_zpsfbdc939f.jpg.html)
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Plain old packing tape works as well :)
Don't try to make it 'look' even. The strung and drawn shapes should reflect the unbraced shape.
The simple way to tiller any bow is to watch the set that appears and its location.
Trace the profile onto a wall or something and every time you unstring it place it up against the original profile. No set inner limbs a little mid limb and the rest in the outer limbs.
Works everytime on every wood bow.