Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: longrifle on February 24, 2015, 10:09:00 AM
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I've been using the taught string/ overhead light bulb way but always struggle with ,is it exact or is ther a better way. Tell me how you do it.
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Taut string... and if it is elevated far above the handle, I level the limbs, then drop a plumb line from the taut string down to the bow with a combination square. I do it in several places, and on both sides of the string to verify it's correct.
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What are you working on, a glass bow, wood lam bow or selfbow?
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I use a center finding ruler in 64th. Of an inch, can't get much closer than that.
RW
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I'm making glass bows right now
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I use a tight string also, but a laser tool does a good job too.
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Taut string... and if it is elevated far above the handle, I level the limbs, then drop a plumb line from the taut string down to the bow with a combination square. I do it in several places, and on both sides of the string to verify it's correct.
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If the bow is built right and the limbs are straight, what does a centerline do?
James
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Before that. It can be helpful in getting to, and/or verifying, the 'built right' stage.
Following that, lets say on a full recurve, when I lay my limb pattern on the limb to trace it, I have a small hole drilled in the pattern at the deepest part of the curve, and align it so that I can see the centerline through the hole when I push the pattern down into the curve. Otherwise, even if the pattern is centered at the handle and tip, it can move a little to one side or the other as it is pressed down against the blank, which can ultimately cause misalignment and limb twist.
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The pattern will lay up the curve centered unless the curve is twisted coming out of the form. If you clamp the pattern in the center of the tip and align it with a center hole in the curve and mark the limbs and then do you twist the pattern to adjust to the rest of the limb if the alignment is off? I agree that a centerline will tell you if the limbs are straight and aligned after the bow is built.
James
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Mine are all long bows, so I file carefully on the edges of the limbs at the fades, which will be the widest point on the bow to eliminate any lam misalignment. Then I measure to limb center at each fade and then draw a straight line through the two Centers with a flexible 36" aluminum measure. Then that same line is extended straight out to the tips.
All that is done with the tape still on the glass.
None of my limb profiles are ever exactly the same so I have no permanent patterns. Each pattern is printed individually from a CAD program complete with horizontal and vertical center lines. I cut the paper pattern to within 1/8" of the limb profile lines and then use a single hole paper punch to punch holes every six inches along the center line. Then I spray the back down with 3M glue and stick the pattern down aligning the centerline on the tape and the centerline on the pattern through the punch holes.
That said I don't get how you guys do it with a string on your recurves????
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Small square. Mark from each side and adjust to where the lines mark over each other. (http://img.photobucket.com/albums/v75/crookedstic/New%20Pronounced%20TD%20longbow/ElkCountry29.jpg)
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I use a cheap laser line that ive had for years. Works for longbows.
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I put the bow on it's side on top of a dead flat piece of marble. Then use a spacer block with a pen on top that's the right height to cut through center. Check square between bow faces and the bench. Doesn't matter what shape the bow is :)
Then use that center to position limb templates.