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Main Boards => The Bowyer's Bench => Topic started by: PZee on July 25, 2010, 11:08:00 AM

Title: Hinge and Limb Twist - Can it be fixed
Post by: PZee on July 25, 2010, 11:08:00 AM
Hi,

Well I've moved on since my limbs wouldn't move, but now I've got new problems. Can this bow be saved?

(http://i939.photobucket.com/albums/ad240/PZeelie/First%20Bow/DSCF2967-1.jpg)
Original

(http://i939.photobucket.com/albums/ad240/PZeelie/First%20Bow/DSCF2988.jpg)
Hinge

The problem with the hinge is, it seems to have lost some of its reflex in that limb. My bow scale jammed on 40# so I kept on pulling and that happened. This is still all with the long string.

(http://i939.photobucket.com/albums/ad240/PZeelie/First%20Bow/DSCF2989.jpg)
Limb Twist

Thanks

Pete
Title: Re: Hinge and Limb Twist - Can it be fixed
Post by: Shaun on July 25, 2010, 11:29:00 AM
The only save is to make the rest of the bow as weak at the hinge - most likely end up a kids weight bow.
Title: Re: Hinge and Limb Twist - Can it be fixed
Post by: Roy from Pa on July 25, 2010, 09:43:00 PM
Like Shaun said, try for a kids bow. Once you get a hinge, it's a normally a gonner.
Title: Re: Hinge and Limb Twist - Can it be fixed
Post by: John Scifres on July 26, 2010, 08:54:00 AM
Just keep tillering.  Stop pulling it to unknown weights.  It looks to me like the belly slat is thinner in that area.  The key to avoiding problems with tillering is very careful layout and patience.  

Floor tiller until you see a problem.  Correct the problem and then repeat until you are able to string the bow easily.  Then pull to target draw weight and analyze tiller.  Correct problems and reduce weight.  Repeat until you are at target draw weight and target draw length.
Title: Re: Hinge and Limb Twist - Can it be fixed
Post by: Loren Holland on July 27, 2010, 12:03:00 AM
What John said is right, laying it out right is important. As I look at that pics, I am wondering if you thinned out the boo enough. If you back with boo that is too thick or not tapered at all, then you don't keep a good ratio of bellywood to backing, and it plays heck with tillering, adds to sudden breaks or delaminations too.

I took that boo/ipe (that i mentioned i hinged it in the fade in your first post) over to Sam Harper's place this weekend to see what he thought. I was just going to chalk it up to another kid's bow. He a good idea i am trying to use to fix it.

You could go ahead a tiller out the hinge, don't worry about how light it gets, then make it a tri-lam. theoretically if you put on a parrallel at that point, it shouln't change your tiller much at all. my boo/ipe, is now a boo/ipe/boo tri-lam. i used engineered boo on the belly so i could adjust the tiller if needed. top limb if done, and the bottom limb is drying now. from what i can tell it definately fixed the hinge, and now i have the weight back (with the added benefit of maintainng low mass as the boo belly is so light)...just an idea, you might try if you are really wanting to keep a hunting weight bow, plus you could try to fix that twist during the glue up, instead of tillering it out.
Title: Re: Hinge and Limb Twist - Can it be fixed
Post by: Pat B on July 27, 2010, 03:34:00 PM
If the bow doesn't have any twist when unbraced the thickness is uneven which will cause it to twist when tension is added.