UKC

I have recently bought three good quality second-hand cams (DMM 4CU) that are around 5 years old, and am deciding whether to resling them or not... I could send them into DMM for £12.50 each to get it done properly, but that isn't preferable cost-wise. The other option I reckon was to put 6mm accessory cord on them.

My dilemma is that the cord is rated to 8.1kN and the sling was previously rated to 14 kN. I'm not sure whether I will just be making the system weaker by replacing the sling with the cord.

Disclaimer: The slings are in good condition and the seller says they haven't had any falls

5 year old slings in good condition: I wouldn't re-sling them. Plus, re-slinging with accessory cord can be annoying (regardless of the loss of strength issue, where 8 kN is a significant reduction) because you'll find that the knot will get in the way,

Send them to DMM, they'll test them, re-do the trigger wires and re-sling them all for £37.50 and you'll get piece of mind that they're good for another few years yet.  I assume you live in Cheshire so a day in North Wales would be quite common and you could drop the cams off in Llanberis at the same time.

I restringed my friends with Dyneema  cord from Needlesports. I wondered if the knot would get in the way but it hasn’t been an issue. Just make sure you tie it with a triple fisherman’s knot.

Thanks for the advice David, that's what I was thinking as well but I just wasn't quite sure so wanted a second opinion

Cheers everyone, I love this forum so much!

Hey Paul, I don't actually live in Cheshire it's just my surname (I've never actually been there). I'm trying to avoid the cost of having to send them to DMM

As others have said. If the slings are in good condition I'd not change them yet. DMM replaced 3 of the slings on my 4CUs and also checked the cams were OK too. Worth the money. We dropped them in at the factory when we were in Wales and had a trip round it too. Very interesting.

As Wild Country are still not reslinging their cams, yet, I've used 8mm x 30cm dyneema slings treaded through the hole in the stem and clipped both ends to a karabiner. Not recommended by WC, but is it any worse than threading a sling through a small rock pocket?

I wouldn't buy second hand gear I didn't trust.

Stuart

I’ve got a couple of rigid stem friends that still have the original tape on them.

I don’t actually know how old they are, certainly more than 5 years, but I’ve had them from new and I’m happy to continue to use them.

I’m sure that someone will be along with a story of how they fell to their death because their friend failed due to the tape snapping.

Only you can decide what you’re happy with.

Years ago (back in the 90s), i took some of my old carabiners and quick-draws into the mechanical test house at work (British Aerospace).  They did a quick pull-test on them, recording the load vs extension.
I was impressed that both krabs broke at around 2000 kg while the quickdraws got to about 3000kg, almost doubling in length when they finally broke (i think they were 1 inch wide Troll nylon tape).

What i got from this is that tape slings are bloody strong, even when you've used them regularly for a few years.

I'd look at the condition of the slings.  Are they rather longer than they should be?  Do they look REALLY furry?  If yes, then bin them.  Otherwise  i'd be happy to keep them.

You're overthinking it. I have cams from the 90s with the original tapes I would happily take a fall on.

edit: all my gear is stored out of the sunlight so no issues....UV is what weakens slings & ropes

Snap.  I've only just retired a 1.5 ridgid stemmed Friend from 1986.  One of my mates gave me too much stick for still using it and i finally relented.  The suggestion being that the ridgid stem was obsolete rather than the sling being dodgy.

Get one of you old quick draws and try to break it. Bet you can't

I still use Wild Country rigid stems cams in the larger size 3 and 3.5 sizes. They have been re-slung, nominally by Wild Country but the actual work was possibly done by DMM.

I bought them because, back in the day, they were cheaper than the new flexible Technical Friend. (The large cracks for this size usually mean that the rigid stems can be easily orientated in the direction of pull.)

The Wild Country cam book gives the weights of the cams. page 30

https://www.wildcountry.com/media/pdf/c9/92/40/Wild-Country-Cam-book.pdf 

Forged friend size 3 -143gms. 

Technical friend size 3 - 155gms - flexible but heavier.

Brian Cooper above mentions threading a sling and clipping two ends to a krab. Does work well but does have limitations. Drawback of this method is that someone could unclip one loop of the sling thinking they are just extending the sling. Chris Tan covers a method in the link below which does not resolve but makes it harder to unclip one loop.

http://www.kakibusok.plus.com/Equipment/ReslingCams/Resling.htm

Dating - no, not an offer of a night out. DMM cams usually have a product I.D. code stamped on them. It might be worth trying to identify exactly how old the cams are but that would still not tell you how they have been used or looked after.

The decision to re-sling or not relies on so many factors. Whatever you go for just make sure that you stay safe.

If the slings are in good condition and you trust the seller there is possibly no need to resling them yet. But what is good condition? Are the slings beginning to appear furry? The appearance of slings is important as it correlates to their strength. This is especially important for Dyneema which has a markedly shorter lifetime (when in use) than nylon, probably because they are made of less material. On UIAA's webpage Research & information there is an informative article on the subject (Panorama 2015/4 The Aging of Sling Materials), see link:

https://www.theuiaa.org/safety-standards/research-information/

I've replaced the tape on my very old friends using 25cm quick draws. The smaller friends were awkward to thread while the bigger ones were easy. With the tape doubled up the length is 12cm and nearly double in strength. Obviously the quick draw tape was already seamed so no new joins are needed. And I had a collection of light weight crabs left over that I wanted to replace heavier ones.

I'm not sure if anyone can answer this one: is the sling strength reduced to match that of the whole unit with cams? I'm sure I remember reading something about DMM making the strength of the slings on their hexes more evenly match the strength of the hex itself (as the metal is the weakest point). When a cam has '14kn' on the sling, does that relate to the weakest point (e.g. the cam itself) or is the sling rated to that as well? Because in theory, if the sling is of the same construction as their normal dynatec slings, that part of the cam will take ~22kn new. That gives you quiet a margin for any strength reduction over time. 

Out of interest, when did DMM stop making the 4cus?

The rating shown "on the sling" is for the whole unit, as sold. It reflects the strength of the weakest link in the unit. In the case of the DMM Dragon Cam, that isn't the sling. The actual strength of the unit, in reality, is often in excess of the "rating" indicated.