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Main Boards => The Bowyer's Bench => Topic started by: J. Holden on September 20, 2016, 06:52:00 AM
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Hello, I'm wondering if there's a general rule of thumb regarding how many clamps should be used when gluing on a piece of backing. Also are c-clam the preferred clamp or do the spring clamps work just as well? Thanks for the help!
-Jeremy
P.s. For what it's worth the bow I'm backing is ipe, 64", and I'll be using Unibond. First time...
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Clamp every 2 inches. Be sure to pad the back and belly with a thin lam to keep the clamps from indenting the boo and wood. C clamps would be a better option. Don't crank the clamps too tight, just fairly snug. Wrap the bow with plastic wrap to prevent a mess on your form and clamps.
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The rule of thumb is that you'll always need one more clamp than you own.
I would use C clamps every 2 " or so. Crisscross wrapping with bicycle innertube strips also works well.
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This is a trick I learned from Pearl Drums that was very helpful at glue up. I used bamboo skewers as alignment dowels in the handle area. Once you add the handle wrap you won't see them.
(http://i5.photobucket.com/albums/y199/PatBNC/lemonwoodALB008_zpsfbdc939f.jpg) (http://s5.photobucket.com/user/PatBNC/media/lemonwoodALB008_zpsfbdc939f.jpg.html)
(http://i5.photobucket.com/albums/y199/PatBNC/lemonwoodALB010_zpsdbec0a25.jpg) (http://s5.photobucket.com/user/PatBNC/media/lemonwoodALB010_zpsdbec0a25.jpg.html)
I used bicycle tire tubes for clamping the backing to the belly..
(http://i5.photobucket.com/albums/y199/PatBNC/lemonwoodALB001_zps7eda0c54.jpg) (http://s5.photobucket.com/user/PatBNC/media/lemonwoodALB001_zps7eda0c54.jpg.html)
...but used "C" clamps at the handle and fades and also at the tips...
(http://i5.photobucket.com/albums/y199/PatBNC/lemonwoodALB012_zpsddda9521.jpg) (http://s5.photobucket.com/user/PatBNC/media/lemonwoodALB012_zpsddda9521.jpg.html)
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Can you see any gaps?
(http://i1289.photobucket.com/albums/b506/timian46/image_zpsgcydzu7g.jpeg) (http://s1289.photobucket.com/user/timian46/media/image_zpsgcydzu7g.jpeg.html)
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These spring clamps have a heavy bite and the jaws have a sligthly concave surface so they fit nicely on a bamboo back, with a piece of leather as a padding, if one finds it necessary.
(http://i1289.photobucket.com/albums/b506/timian46/image_zpsnm8m61hd.jpeg) (http://s1289.photobucket.com/user/timian46/media/image_zpsnm8m61hd.jpeg.html)
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An RD trilam.
(http://i1289.photobucket.com/albums/b506/timian46/image_zpsg03yir1p.jpeg) (http://s1289.photobucket.com/user/timian46/media/image_zpsg03yir1p.jpeg.html)
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Very nice set-up, Bue. Nice shop, too :thumbsup: :thumbsup: :thumbsup:
But, what Roy said times 2. :)
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Use innertubes from your local bike shop instead. Ask for the ones they have from fixing punctures. Free, last for ages and will give you flawless gluelines and more even pressure than clamps.
Both will work - horses for courses.
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A little trick I have learned is I cut my scrap boo into 2" blocks and use them as padding under my clamps. A perfect fit to the back of the boo and gives me a very good glue line. I prefer the spring clamps.
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Bue I really like those clamps. What's the brand name?
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Roy, the brand name is Cocraft. The clamps come in different sizes, I use the ones that can open the jaws 55mm. Cocraft produce all kinds of tools. Bue
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Thanks Bue
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Thank you for all the advice. Is there a trick if using inner tubes to keep it from sliding while wrapping? Seems to me while trying to make it tight it would slip around.
-Jeremy
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You needed one more clamp Bue
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The bamboo skewer alignment pins I mentioned above will keep the backing from slipping while you wrap the tube bands. That is how I "clamped" the bow in the pic. It isn't boo but a hickory backed lemonwood.
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I also pin the riser section as Pat showed. I also pin the ends of both limbs by drilling a hole on each side of the tips. I drill the limb tip holes right up against the backing, but not in the backing. I use toothpicks in the holes. Then I wrap blue painters tape around the mid limb area. Everything stays aligned while clamping.
I've never used rubber bands, but I'd imagine you would pull down equally on both ends and slip the ends over the pegs simultaneously.
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When I use my rubber band jigs, I start with a center rubber strip to hold everything in place.
(http:// [url=http://s21.photobucket.com/user/kenhulme/media/My%20Yanghai/MarkIIForm-Symmetrical_zpsad1756fb.jpg.html] [img]http://i21.photobucket.com/albums/b282/kenhulme/My%20Yanghai/MarkIIForm-Symmetrical_zpsad1756fb.jpg)[/url] [/IMG]
Then I work out from center in both directions. I hook the rubber over one end of a peg, then pull up and over and slip it onto the other end of the peg. I alternate sides on which I hook, to help keep pressures even. Have not had any problems with slippage.
(http:// [url=http://s21.photobucket.com/user/kenhulme/media/My%20Yanghai/YanghaiStrung_zpsd2f32e69.jpg.html] [img]http://i21.photobucket.com/albums/b282/kenhulme/My%20Yanghai/YanghaiStrung_zpsd2f32e69.jpg)[/url] [/IMG]
Because this shape is so 'stressful' to assemble for one person, I glue up the back glass and the core lams, then in a second session I add the belly glass.
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Jeremy on the inner tubes.
When starting each section have to hold the end and wrap overlapping so it holds then move down slightly overlapping each wrap.
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I take a bike inner tube(free from bike shop trash), cut the valve section out and cut the tube into 2 ling strips. I start wrapping at the handle and work out to the tips. Once both limbs are done I clamp the handle area to the base of the form and lift each tip on to a 2x4 block. I add extra clamps at the fades and the tips.
I don't think you can wrap the tubes too tightly around the bow.
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All great info! Thank you.
-Jeremy