Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on July 26, 2015, 04:05:32 pm
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I'm making up a boo backing for a spliced yew bow. If I run a string down the center of the backing strip it has a slight bend to one side. The string misses the center by 1/4". Will the rest of the bow pull this straight when I glue it up?(I doubt this) If I just cut the boo following the string that will give me a bit of run-out on the boo. Can I heat bend the boo sideways so it's straight when I glue it up?
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No! Nothing will ever work in your favour!
if the Boo has a slight twist but is V thin you will prob be ok. but don't expect anything to pull anything else sideways into line.
I learned a lesson with a boo backed Yew. There wasn't much Yew to play with and it didn't really line up right... but I clamped it all up...
It was fine for a few days then too a sideways bend... I tried all sorts of trick to correct the bend... they all worked for a few days or a week.
http://bowyersdiary.blogspot.co.uk/2015/03/the-returning-bend.html (http://bowyersdiary.blogspot.co.uk/2015/03/the-returning-bend.html)
In the end I sawed it in half :o. Re-jigged it straight and made it into a take down :).
If it's wrong before glue up, it will be wrong after.
If it's right at glue up... it may still be wrong after. The way to be be safe is to have plenty of spare wood ... but we all know you can only work with what you have.
I'd say cut the backing strip dead straight ignoring any "grain" in the boo. Try top get it flat and evenly thin... may even be worth steaming it flat (but don't try to correct sideways bend)
All the above is only my best guess... can't beat careful preparation with any glue up. Others may have better advice to offer.
Del
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OK so I shouldn't force it(I thought not). So should I cut the boo so it fits or will heat work to bend the boo?
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If the bamboo strip has been properly thinned a 1/4" offset is not going to be a problem.
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Yes,i have heat shaped bamboo before.
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The bamboo will easily move over the 1/4". I have never measured before but more than 1/2" bow in the bamboo after I cut it is not unusual. It pulls right over when you wrap it with the bands.
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I just cut the Bamboo to fit and ignore the grain
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I'd cut it to fit now - pre glue up.
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I like cutting the boo to the front profile shape before glueing up. If you decide to do so I don't think you will have any problems, just ignore the grain like Marc said. Be sure and thin the boo again after you cut out the profile.
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So what is the optimum thickness for boo?
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1/8" at the fades at the crown. You can taper to the tips or not
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Thanks Pat
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I've cut it to match the profile. I have to sand it a bit thinner. But I've got chores first :( :(
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I just cut the Bamboo to fit and ignore the grain
yup
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Pearls of wisdom here. Match it to yer wood, carry on. But as Del sez, it will reserve the right to go wrong.
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Cut the bamboo in half, then lay out the limbs on each piece and thin them...lap splice at the handle.
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It's a billet bow that may bend in the handle a bit. I would just as soon have a one piece back. I will save that thought for others though.