Author Topic: Board Bow - Laminated Handle Breaks  (Read 2211 times)

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Offline BrokenArrow

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Board Bow - Laminated Handle Breaks
« on: April 30, 2014, 04:32:15 pm »
I have a tri-lam bow in the tillering process and have laminated 2 handles with EA 40 and both have broke in the draw.
I have not had this happen before and am wondering what solutions to the lam riser people have tried.
One guy suggested leather instead.
Please advise?

Offline bubby

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Re: Board Bow - Laminated Handle Breaks
« Reply #1 on: April 30, 2014, 04:47:35 pm »
got any pics? sounds like it's bending in the handle area somewhat, you can build it up with leather, rawhide or cork, I've done all three and I favor the cork now
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline Wiley

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Re: Board Bow - Laminated Handle Breaks
« Reply #2 on: April 30, 2014, 05:03:29 pm »
It does sound like that area of the bow is bending too much. For a stiff handled bow you want that area to not bend, if it does the handle pops off. This area can be made stiffer in a couple different ways. One if to leave the belly lam thick enough that the handle area remains static even without more lamination to build it up and fade handle into working limb, no bend no popping the handle off. Or you can glue the handle to the core lamination and run the belly lamination up the handle fades. The other method is to make a taped piece of wood that is longer than the riser and fades will be and to glue this in between the back and core laminations. The common idea between all of them is to put less stress on the glue joint.

Scroll down to the bottom of this page, some pretty good explanations of what is happening, and how to avoid it in future bows. As for this one, build up the handle with leather, rawhide, cork like bubby suggested and let it bend in the handle the a little bit.
http://poorfolkbows.com/ipe1.htm

Offline DarkSoul

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Re: Board Bow - Laminated Handle Breaks
« Reply #3 on: April 30, 2014, 05:12:38 pm »
Can you post a picture? What part exactly broke? The handle itself, or did the bow break, or did the handle pop off?
A powerlam can prevent bend in the handle. A powerlam is a short (about 16 or 18") lamination in the center of the bow, glued between two other lams, that tapers from zero, to 1/8" thickness in the centre to zero again. It thickens the handle enough to prevent bend. After the powerlam, you can glued down a solid handle of any wood, cork or leather.
"Sonuit contento nervus ab arcu."
Ovid, Metamorphoses VI-286

Offline Blaflair2

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Re: Board Bow - Laminated Handle Breaks
« Reply #4 on: April 30, 2014, 07:55:34 pm »
Make ur handle laminations very thin and build them up. They should stay on
Nothing ventured nothing gained

Offline Hamish

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Re: Board Bow - Laminated Handle Breaks
« Reply #5 on: April 30, 2014, 09:09:10 pm »
Does the bow have a centre shot, cut out arrow pass?

mikekeswick

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Re: Board Bow - Laminated Handle Breaks
« Reply #6 on: May 01, 2014, 03:21:47 am »
Just making them thin doesn't always cure the problem. Once a handle riser 'pops off' it's time to give up imo because it shows that the design isn't correct. Building it up with leather/cork etc doesn't stop the problem. A stiff handled bow should be stiff handled and adding lether etc does not stop that bend happening, indeed a bow that is bending in the handle when it's not meant too will be stressing the heck out of the narrow handle portion which has become part of the working belly.
Solutions - make your belly lam thicker so that it is part of the fades or use a powerlam.