Primitive Archer

Main Discussion Area => Bows => Topic started by: grantmac on May 15, 2008, 03:50:20 am

Title: Had a string blow off today.
Post by: grantmac on May 15, 2008, 03:50:20 am
I was doing a few short-draw trial shots with a new bow I'm working on (Boo, Hickory, Ipe tri-lam R/D) and I had the string come apart at the boyers knot (fast flight with too few strands). That was quite the experience, I'm glad I wasn't at full draw and that the arrow safely left the bow. On the other hand it really underscored just how much more force is put into the string as the bow hits brace height in a high brace-tension bow. It also let me knoe that this bow will most likely have very little handshock once it's finished. As for damage I don't think there is any because of the very light limbs in this design.
     Cheers,
             Grant
Title: Re: Had a string blow off today.
Post by: Cromm on May 15, 2008, 04:35:34 am
Eekk...... And Ouch! :D
Title: Re: Had a string blow off today.
Post by: Rich Saffold on May 15, 2008, 01:54:52 pm
Grant, If you are using a timber hitch on the bowstring you really need to make the lower nock fit it. I round the belly side of the nock to accommadate the oval/round shape the timber hitch wants to take.

The second trick is when tying the timberhitch, you want to wrap the end about 6 times around the loop on the first pass, then do it again, yes twice.  When snugging it on the lower nock you want to pull on both the string and the end of the string..both ways to cinch it tight..This keeps it from slipping and cutting the bowstring which I'm sure caught your attention... :o ;D

Rich

Title: Re: Had a string blow off today.
Post by: grantmac on May 15, 2008, 06:23:46 pm
Little update on this:

The bow lifted a splinter on the belly today, looks like that rapid decel was more than it could take. Pity really because it was looking to be a really nice shooter. There were some things I'd change in the design so I guess this is my chance.
     Cheers,
            Grant
Title: Re: Had a string blow off today.
Post by: Pat B on May 15, 2008, 08:35:07 pm
Super glue, wrap and continue! ;)       Pat
Title: Re: Had a string blow off today.
Post by: grantmac on May 15, 2008, 09:39:54 pm
Maybe, I can see a tiller change where it is so I'm not sure it'll work. It's sort of off the edge and you can see it lifting down to the glue-line. Perhaps some warm epoxy could be convinced to make it's way in there. I suppose there is no loss when I'm willing to chuck the bow as it is. I think part of the problem is that my belly strip is getting very thin to drop the weight. The limbs are trapped but maybe they can come down further.
      cheers,
             Grant
Title: Re: Had a string blow off today.
Post by: D. Tiller on May 15, 2008, 10:35:06 pm
Beef up the bowyers knot area of the string and up a few inches with extra strands. Makes it stronger in that area without increasing the weight of the string too much.

David T
Title: Re: Had a string blow off today.
Post by: grantmac on May 16, 2008, 01:43:49 am
Already done with this next string. I'll pick-up some CA and try that in the next few days or so. Until then its onto the next bow.
     Thanks,
           Grant
Title: Re: Had a string blow off today.
Post by: recurve shooter on May 16, 2008, 10:35:27 pm
lol. sounds like something that would happen to me. both of my strings are currently broken. :-\