It's frustrating!!!! -- String Nocks (Pics added)

[Marvin M.]

Last winter I finished up my first laminated bow using Bingham's instructions and kit (take down longbow -- 55 @ 28).  Didn't get it done in time to use it last year so it was supposed to be first up this year to get bloody.

Been shooting it this year in preparation.  So far, I've broken five strings in it!!!!       I'm making my own strings out of B50 and they're good strings (if I do say so myself).  Had friends that have used them for years.  So I don't think it is the strings.  

The last one that boke was at the top nock.  Took it apart, filed, sanded, smoothed, put it back together and made another string.  That was about six weeks ago.  Today, seventeen days from the season opener, my string broke again in a shooting session.  Didn't see it coming.  This one was at the bottom nock and all the others have been at the top.  Been watching the top like a hawk to make sure it wasn't fraying and it hasn't been.  Out of the blue it breaks at the bottom nock.  I use a stringer so I look at both nocks stringing the bow.  Didn't notice anything going on at the bottom nock, but didn't examine it minutely.

It was pretty impressive.  I felt a sting on my bow arm and felt the bow kick.  The arrow hit where it was supposed to and the string flew in a nice graceful arc that landed five yards to the right of me.  The bow seems OK, especially for a bow that has had five strings break in it, but I'm losing patience with this.

Looking at the string, it again parted at the nock.  String didn't unwind, and it looks like a clean cut.  Don't have my camera with me at work, so will try to post some pics tonight or tomorrow.  Top loop has some fraying on it also, so I didn't completely get it corrected.  It's got to be the nocks on the bow.  I'll take some pics of them too and see if anyone has any ideas.

Needless to say, my Martin Savannah will be moving back to the number one spot for the opener!  Don't want any problems when a deer is under the stand.

I'm thinking the first order of business is to get something fragile or "sticky" to pull through the nocks and see if I can find any sharp edges.  Maybe sneak a pair of my wifes panyt hose or something.     :D  

I'll be pictures when I can, but would love input from you guys that have dealt with this.

[Dano]

The edges don't have to be sharp, they could just be too abrupt in the way of string angle.

[eman614]

i feel your pain as i am having the same problem. think i got mine fixed though. good luck fixin it.

[Jesse Peltan]

Your string groves have too abrupt of an angle. Brace the bow high like 8in or so and mark where the string angle with the bow limbs, then file in the new angle.

[dutchwarbow]

- how many strands do you use?

- what's your bow's drawweight

- did you use a single spool or several (you might just have gotten a rotten one?)

- let's see some pics of your nocks!!

Nick

[Marvin M.]

Couldn't find my camera last night to take pics.  I can try it with the cell phone, but don't know what quality I'll get out of that.

Dutch,  I used different spools for the strings.  I've got several available and swithced colors to make sure I wasn't makeing the same mistake.  The bow is 55 @ 28 and I was using a 16 strand string.  Should have been plenty.

I'll try to take some pics at lunch with the cell phone and see if I can ge something that will show them enough for an examination.

[Marvin M.]

OK, I sneaked out to the parking lot and took so shots with my cell phone.  Not real good quality, but you should be able to see enough to tell what the nocks look like.
 

 

 

Those are all shots of the bottom nock, where I had the problem yesterday.  Tell me what to do.  The bow itself is 68 inches nock to nock (according to the plans anyway), so the length should not be a problem.  The string dows track down the center and my brace height that works best is seven and three quarters inches from the handle.

Below are pics of the top limb nocks.  This is where I have had problems in the past.  

 

 

 

 

What about it guys?  What do I need to do?

[Dano]

The problem is the angle the knock is cut, it's at 90 degrees and it needs to be about 35. Here's an idea of what I mean.
   
You should also round over the groove in the overlay, so it isn't so square.

[Marvin M.]

Dano,

Can I just take off the edge to correct the angle?

My overlays aren't thick enough to really put a groove in.  Can I add something to "beef them up" and put the groove in that?  I've got some sheds laying around.  I could probably split one of them and add that to it, and still leave the phenolic in there as a spacer.

[Dano]

Yep just correct the angle, sounds like a good plan, probably look great too.

[Holm-Made]

You have enough phenolic to round the top of the grooves a bit without going completely through it.  You said your using B50 and with B50 you really don't need any overlay at all, but they are nice.   Chad

[Marvin M.]

OK, I'll see what I can do with it tonight.  Should be able to squeeze out a little time to work on it.

[Shore08]

Hope that fixes it for you! If it does, show us some more pics of your bow.

[DCM]

http://home.comcast.net/~dcm4/Old%20Bow%20Stuff/bcb1.JPG

You want the string grooves to form a teardrop shape.  Also for the string to lay straight to the back of the bow at brace height, not curving around (much).

[Marvin M.]

Thanks guys.  Didn't get a chance to work on it last night, but might be able to get started at lunch today if I skip some of my shooting time.

I'll try to get them re-worked and post pictures for everyone to see.  This might help someone else.

[Jason Jelinek]

Also make sure there are no sharp edges on the fiberglass on the belly of the nocks.  They will wear on the strings.  Just a bit of work with a file and/or sandpaper will take that edge off.