UKC

Has anyone read any gear tests of frayed wires? How many broken strands is too many? How many do you put up with? I had a great idea to replace all the broken ones but its going to cost a bomb.

In reply to burdy:

Depends on what the wire is for?
cam trigger?
Brake cable?
Wired chock?

In reply to Fredt:

Agreed. If it's attached to a nut, then any fraying is too much. Although that doesn't tend to happen often. Wires my BD camalots are frayed, I use them till they break then buy a new trigger kit.

In reply to burdy:
You have to ask the question how many are broken within the core? Aviation industry assumes one visible broken strand in any control cable = change cable is a mandatory requirement.

http://www.ukclimbing.com/forums/t.php?t=552865&v=1#x7376565

In reply to burdy: None! No from a safety point of view but simply because it hurts like buggery when you stab you finger with a frayed wire. I usually find I damage them but using ice tools instead of a nut key. Frayed one <if not too bad> get relegated to the winter rack. At least I've got gloves on while using them

In reply to burdy: The strength reduction will be proportional to the number of wires broken, i.e. if 10% are broken it will lose 10% of its strength.
If I had a wire nut with 1 or 2 broken strands I wouldn't worry it was going to snap if I fell on it but I'd probably replace at the next convenient opportunity. In part because, as has already been mentioned, it hurts like buggery (not literally) when you stab your finger on them

In reply to jim jones:
>

I read somewhere tghat there is serious concern about the number of broken strands within the Forth Bridge main cables that replacement is overdue.

This will result in the bridge having to close for years which means a new bridge is overdue....

In reply to Trangia:

That'll be the Forth Road Bridge opened in 1964 and already knackered. Replacement is already under construction to be completed in 2016 at a cost of £1.5 billion.

The Forth Bridge, on the other hand, opened in 1890, is still going strong . . . .

In reply to burdy: is £65 for a new set of 11 dmm nuts really that expensive? considering you're trusting them with you're life its not that bad imo

In reply to Martin Bennett:

I saw that. Was it on Coast? They have monitors on the giant cables and you could hear the individual strands breaking.

E

In reply to burdy:

Thanks for all the replies, I was asking about nuts.

The reason I started this thread was that I had a little mantra stuck in my head that if one of the smallest threads that make the wire breaks it means that the strength is probably greatly reduced (or it is just a good indicator that it's time to replace). The spikes in the hand I can usually take on the chin and I am not too worried by them. I am searching for some wisdom, maybe a link to a test report. As I have put it off and now loads are knackered, so if any one knows the cheapest place to get a new set of superlights, offset DMM brassies, dmm big offsets. eek

Thanks

Thanks

In reply to Trangia:

Roll on the Fifth Bridge.

In reply to burdy: I wouldn't be worried about a few broken wires in terms of strength reduction, but I would treat that as a sign of age and usage and replace them based on that.

In reply to Martin1978:

What are you basing that on? Do you know of some tests? Because most seem to be saying any fraying is bad, presumably because there's nothing better to go on other than playing it safe.

In reply to Jonny2vests: Taken in the context of the rest of my statement* I'm not basing it on anything. If I was I would have referenced it.

I would use broken wires as an indicator for retiring them, based on the fact that new wires don't have broken strands but wires subjected to falls, fatigue, or poor storage/placements may do. So I would retire them because of this. Given these factors, trying to guess or research any reduction in strength isn't relevant to me when making the decision to retire them.

Hope that clears up my original comment (not that I'd expect anyone to make a decision based on one persons comment on the internet, selectively quoted or otherwise).


*note the use of "me" and "I", suggesting opinion rather than fact.

In reply to Enty:

I saw that, the interesting thing was they were counting the strands as they break (but did not know for sure many were already broken when they started monitoring!)

In reply to Jim C:

They're pumping dry air through the cable "bundle" to stop corrosion but not sure how much they've managed to extend the lifetime of the bridge.

In reply to burdy: Hahaha, I think the Fourth Road Bridge hijacked your thread.

In answer to the OP, I tend to think that one or two broken wires on a nut are not a serious threat to its holding power (although as folk already said, sticking yourself in the finger is extremely annoying). I buy the odd replacement or sometimes sub in a situ piece I found somewhere (yeah, I know that's a reallly safe way to go) when the sticking gets annoying.
I would replace any microwires as soon as any wire broke.

It's worth considering that if you can see a couple of broken wires on the outside of the nut, that doesn't mean that there couldn't be another couple broken inside the wire cluster.

In reply to pec: "The strength reduction will be proportional to the number of wires broken". No it won't, it depends on that and also what caused the break and hence the level of damage to other strands. There is no way you can judge this so its way more sensible to stop using them if this happens.

In reply to wilkie14c:

This ^^

In truth, though, frayed wires isn't something I get very often

In reply to GrahamD: I used to snip off the excess wire then cover the exposed strands in araldite to so stop jabbing myself in the fingers - which works really well. this seems like a good idea until that piece is your last one or a long way and you think hmmm what’s actually underneath all the glue - I then decided the cost of some new nuts was probably worth my life and started binning them.

In reply to burdy:


Totally up to you.


I'll tolerate one or two so long as they're not getting stuck in my hands or lips while handling the wires. Each broken strand probably represents about 3% reduction in strength but each wire broken suggests others may be weakened or broken and hidden in the core.

jk

In reply to Jonny2vests:

Ha ha!

In reply to jkarran:

Many moons ago I remember reading that wire cables are particulary prone to losing strength as soon as even one strand breaks. Bearing in mind that your gear is probaly at least 100% strength redundant to start with, this might "not matter", but don't assume that you can count the strands and as long as half are intact it won't break - it actually could break after two of three strands go (assuming there are about 10). I have a vague memory that losing two strands represents up to 50% strength loss - but memory may fail me.