String: Breakage!

[Vanya Goud]

We had an incident at our club last night, something I have never witnessed before, a recurve string breaking at full draw. Luckily no injury occurred.

The entire bow set up was new 3 months ago (Winstar II, Sammick universal limbs 28 lb @ 28") and has not been shot that much, once or twice a week for those three months. The break occurred under the serving, about an inch above the nocking point. There were no visible signs of wear on the serving as you would expect if the tab were the cause, but when the serving unravelled after breaking it looked like almost all the string threads had been cut clean through with just one or two strands having ragged ends you would expect from breakage.

My question is....what could cause this?

[MATTeL]

Originally Posted by Vanya Goud

it looked like almost all the string threads had been cut clean through with just one or two strands having ragged ends you would expect from breakage.

My question is....what could cause this?

A knife?

It sounds was if the strands were damaged before or during the serving of the string and the "ragged" strands were the ones that were taking all the tension which the obviously couldn't cope with.

What string material was it?

I have experianced something similar with my first dacron string, there were strands that seemed to be cut just above the bottom serving, straight out of the packet.

[inkystu]

Was it a tied on nocking point? It sounds like an accidental slip of a knife that has gone between the serving when trimming the nocking point or maybe top of the serving. Bet the poor archer nearly pooed their pants!

[Vanya Goud]

I think was a dacron string, the standard machine made string supplied with beginners kit, with a crimp on nock. A knife should have been no where near it.

I suspect a manufacturing fault, but my concern is damage the incident could have caused to his bow limbs. I recommended going back to the supplier with the offending string and suggesting that they replace the limbs too.

Perhaps he should push for replacement trousers!

[Zef]

It seems a bit unlikely to be nock related if the break was an inch above the nocking point. Unless the brass nocking point was put on in the wrong spot and whatever technique used to remove it damaged the strands.

[VinZ]

This used to happen with Kevlar/Vectran/Twaron strings. It could happen after 1000 shots on heavy bow. ID what it is.
Google "tensiontech fibres guide" first hit (can't post direct links yet)

[Zef]

Fibres Guide | How to Identify synthetic fibres in Ropes | TTI Tools & Guides

That?

[Nic Rhodes]

Originally Posted by Vanya Goud

Perhaps he should push for replacement trousers!

for all of us .......The string looked hardly used but did go with a 'bang'.

[VinZ]

Originally Posted by Zef

That?

Yep, that's the one (thank you). If it's kevlar/twaron/vectran it is a common failure and the wrong material has been used to make a recurve string.

[TJ Mason]

Is there any sign of chemicals or glue in that area? Some glues will damage polyester (for that is what Dacron is). Perhaps a bit of glue was used to hold the thread in place when starting the serving, and it made the string material weak or brittle.

[King Custard]

TJ's post most reasonable so far i think.

though i do remember having a very irate and tantumming child take a craft knife to 3/4 of the strands in my bowstring once - I'd punished him...so he was going to punish me.lol

but then I'm sure you haven't made someone so mad - that they want to even - have you???

[Vanya Goud]

I couldn't see any glue in the area, but with a bought string you never know what method has been used. We wondered if it was some sort of clamp used when the serving was started off.

I am sure it wasn't sabatage....we are a very sociable bunch with no underlying tensions....well nothing that can't be settled by scoring a few dozen arrows.

[whiz]

How about the most illogical most outlandish possibility ever?

I mean, it's not like there's a history up until synthetic fibers took over that strings ever broke on bows, is it?

My suspicion is.... that the string broke because the force on it exceeded it's ability to hold it.

Gee you guys go into incredible depth over such inane things.

If you dropped a glass and it broke, would you be calling the manufacturer of your floor coverings?

[geoffretired]

Whiz, I think it is very unlikely that the string broke because it was under too much strain. I think it takes something like 4 strands to be safe and the rest just make it thicker so the nocks fit properly.
If the strings had been cut through in the serving process, the strings that were still in use would have been under tension and the others would be loose-ish. The loose ones often show as a spiral twist along the string.Did the string look nice and round when it was being used or did it have that liquorice twist look?( probably too late to ask that now)
I wonder if it could have anything to do with a platform tab; some platforms may have a sharp edge that could contact the serving about 1" above the nocking point. That may be a very unlikely cause; but it is worth checking out. If it is the reason for the cut strands, it will probably happen on the next string, too. Not worth the risk!

[whiz]

You THINK that it takes at least four strands to be safe?

The evidence as presented leads to it being a random event.

No wear and broken strands that can't be discerned as being cut or not because of the way people don't know about how string breaks.

How could a ledge that moves away from a string under tension cause a problem?

Strings break if they're not made properly or have worn out.
Accept that as the most simple truth and go shoot arrows.