UKC

I seem to be on a roll with the silly questions so here's another one to test your brains!

How should I go about putting some new slings on some old but worthy DMM Mambas?

http://www.flickr.com/photos/92041466@N06/8361885335/lightbox/

DMM won't resling anything over 10 years old, but they are too shiny to be in a museum and deserve to be used and scratched, maybe even fallen on...
That's fated well and truly tempted.

Can I tie tape in a double fisherman's knot, or is that the kind of thing that would make the Americans gleefully shout "Yer Gonna DIEEEEEE"?

I've had a browse around the Chris Tan website but he only mentions cams..
http://www.kakibusok.plus.com/Equipment/ReslingCams/Resling.htm
..which I'm plucking up the courage to do.

Part of me thinks that if the double fisherman's knot is too dangerous for CT then it's a crazy idea.

The easiest would be a larks foot, but I'm not convinced the sling would sit right on the end of the krab.

Thanks in advance for any wisdom

In reply to cuppatea: You could potentially make them into sling-draws with some 60cm 8mm dyneema. thread it through the captive eye of one, clip it into the other one.

In reply to cuppatea:
Knotting dyneema is a bad idea.
Someone posted this on the boards earlier:
http://dmmclimbing.com/knowledge/knotting-dyneema-vid/

In reply to higherclimbingwales:

That was quick! Thanks

I did have a half a plan of threading a sling through the captive eye of one and then using a "normal" krab to clip both parts of the sling (if you see what I mean) like in the Chris Tan link, but it seems there may be a risk of the top krab only clipping ONE half of the sling if it were removed and re-clipped, for example if it was used for belay building.

Like in this pic
http://www.kakibusok.plus.com/Equipment/ReslingCams/DSCF3682a.JPG

Perhaps if I went down that road it would be safer to use the draws for extenders only, and remember never to take the top krab off.

In reply to joel182:

Thanks joel182! I'll have a look at the video

In reply to cuppatea: That's how I was meaning. using a 'normal' krab would be a good idea I suppose.

In reply to cuppatea:

What's wrong with just carrying on using them as they are? Is there any notable degradation in the sling? Are they likely to fail? They look in good order.

In reply to cuppatea:

They can be reslung with NYLON tape of the type used on them originally, but using a tape knot (google it - it's like a rethreaded overhand). They must be checked and tightened before each use, however - plenty of climbers got hurt by slings made in this way before bar tacking became widespread. As Joel said, don't tie Dyneema - it's slippery as balls.

In reply to cuppatea:

Yup. Just buy some tape and tie it with a water/tape knot

http://www.animatedknots.com/waterknot/

HTH

David

In reply to joel182:

Ouch. That's the Dyneema plan out the window!

In reply to Jamie Bankhead:

Paranoia! But you're right, I got them from my brother and they've probably seen rock twice.

In reply to climber david:

Thanks David, I've just been looking at GO and found tape by the metre

In reply to stewieatb: i use tape knots on some of my cams using nylon tubular tape. i tightened them several years ago using body weight. Youd never get the knot undone now they are that tight and there has not been any descernable knot slippage and the slings are safe as. houses..... I finished the knot with half hitches and sewed the tail end down to them selves. Like this the knots need checking very rarely....

In reply to cuppatea: i doubt the result will be stronger than what youve got already. i looked in to nylon degredation due to time alone (ie dark dry storage) and found it actually has almost zero effect despite what some manufacturers tell you. Its chemicals and abrasion that will have the main effect......

In reply to CurlyStevo:

Thanks everyone! Despite my random question and the late hour there's been a lot of friendly help freely given.


Stand by for the next installment in the cuppatea old climbing gear paranoia game..after I find my wires!

In reply to cuppatea:


So what exactly do you think has happened to them to merit paranoia?

They'll be good for 20 years plus at current rate of usage, absolutely fine.

In reply to cuppatea:
this should help http://www.google.co.uk/url?sa=t&source=web&cd=2&ved=0CDMQFjAB&...

In reply to cuppatea: if you push a sling through the hole and then pull that back over the top of the crab. if that makes sense, it would look a bit like this if one of the ropes was a crab http://www.uspowerboating.com/Assets/TrainingDept/Powerboat+files/Education...

i will see if it works and take a photo in the morning, it might sit a bit odd and could pull the gate open(maybe).

In reply to itsThere:

That's the same as a lark's foot and is very weak.

In reply to itsThere:

In reply to stewieatb:

Thanks both, I did think about a lark's foot but didn't think it would sit right on the krab, didn't realise is was so weak.

In reply to cuppatea:
Larks foot is about 40% - 60% the strength of the rated sling. So probably not that far different the strength of knotted tubular tape!

In reply to cuppatea:

If they were mine I would use them as they are. Knotted tubular tape would be second choice.

CB

In reply to cb294:
I think I'd bin them once the original slings have worn through my self. Only because there are lighter quickdraws out there and wire gates can be safer (gate flutter etc) and I wouldn't really fancy the added bulk and potentially reduced strength of the knotted tape option.

In reply to cuppatea:

All this technical discussion is meaningless; they're fine as they are.

In reply to cuppatea:

Why bother, they look mint. Personally I'd just use them.
jk

In reply to stewieatb:

It is proportionally very weak compared to an unknotted sling, but in a brand new sling should still hold well over 11kN, so should still be stronger than your smaller nuts.

To be honest though, I would probably keep using the current slings. I have a Mamba on my sport rack still, and it is my favourite draw for difficult clips. I had a bunch of my older and most battered slings tested a while ago, and while some had lost a lot of strength, none of them failed below 11kN (and those were heavily used 18 year-old nylon slings).

In reply to CurlyStevo:

Aye, modern kit seems a lot lighter! I picked up a half dozen camp photon wiregate quickdraws the other day and they are so light it's almost like they're made of plastic.

In reply to Monk:
I had a bunch of my older and most battered slings tested a while ago, and while some had lost a lot of strength, none of them failed below 11kN (and those were heavily used 18 year-old nylon slings).

That's interesting to know, paranoia is a powerful marketing tool

In reply to cuppatea: If you're worried, just get some nylon tape and make new slings with the appropriate knot.

Slings do weaken with age, but probably only to a level to worry about if you have left them in the light. Nevertheless I wouldn't be as categorical as some above are about them being "fine". I don't know where you've stored them for instance.

Anyway, have a read of http://www.blackdiamondequipment.com/en-us/journal/climb/all/qc-lab-gear-do... and see what you think.

In reply to TobyA:
"Slings do weaken with age"

This makes some interesting reading it would be good to see similar tests on slings on different types. I suspect the results may be similar though.

http://www.fishproducts.com/tech/Ropeshelflife.pdf

In reply to cuppatea: If you like, I run a testing service for old extenders, especially DMM Mambas. The testing period is quite lengthy, perhaps several years to be fully conclusive. So if you pop them in a jiffy bag with a SAE with the right return postage and send the to me, I'll conduct a free and comprehensive examination of them free of charge for you and then send them back to you once I'm done to let you know if they were ok or not.

In reply to cuppatea: I'd echo what others have said and use them as they are, if what you say about them having only been used a few times is true. Usual disclaimers apply about having not stored them in the sun with lashings of battery acid.

In reply to TobyA:


I may have overstated the case, but I'm seeing increasingly absurd levels of gear paranoia on this site. Generally speaking it's not the gear that fails!

In reply to mike kann:

Thanks, Mike! A kind and generous offer.

I'm going to have to force myself to decline the temptation as an exercise in character building.

In reply to cuppatea: But they may not be safe. You really really ought to have them checked. Normally you would pay loads a wonga for a service like this. But they way, I am also a Nigerian Prince looking to pay you 1 million pounds sterling... if you could just give me your credit card details I will put the money straight onto your card.

In reply to cuppatea:

Obviously I should have added a caveat to that! All the slings were of different ages and different states of wear. While it was reassuring that nothing was about to kill me, it was still far less than perfect. I have much newer stuff now (obviously, as my old stuff was destroyed in testing).

In reply to Jamie Bankhead:


I'm sure this is true, but nevertheless try to have a reasonably informed idea of how things can break and why, does seem sensible. I think for many of us punters, who aren't sport climbing at a high level, we should consider that a fall could actually be quite a big one because its likely to be from something unforeseen going wrong rather than just trying something physically very hard. Have you seen Andy Nisbet's story in the most recent Climb about falling off Poacher's Fall? One of things he notes is he broke a TI ice screw in the fall. I was thinking about it, and I think I had retired mine by that point almost certainly because I had read here or elsewhere of the first internet stories of their hangers shearing through the tubes. Of course Andy could cruise a route like that normally, but bad luck happens - and its then that we need our gear to work.

In reply to TobyA:
Toby you say slings weaken with age, can you provide any evidence of slings weakening with age alone?

In reply to CurlyStevo: Sorry, I meant in the sense of as you use them, so that is mainly UV I guess. Have no idea if you made a quickdraw, sealed it in a dry, dark box etc. whether it would change at all. Another interesting test for someone to do.

I keep a rack of now rather old stuff at my parents' in the UK to use when I'm visiting (including some Mambas). So I'd be really interested to know if there is any reason for me to not carry on using once or twice year some old cams and quickdraws where the slings are now over a decade old, in some cases more like 15 yrs I suppose!

In reply to CurlyStevo: Indeed - I thought that being UV inert was now part and parcel of CE specifications on all PPE. I could be wrong... I hope not!

In reply to jkarran:


I actually thought the crab looked quite worn at the 'rope-wear' end! (You can see a definite groove, or are my eyes playing tricks?) I have some old Mambas and no longer use them for that reason and because the slings are pretty scabby now too.

In reply to Fraser:
I believe they are manufactured with that groove to 'hold' the rope next to the back bar.

In reply to Fraser:

There's a scratch at the bolt end

In reply to CurlyStevo:

You're right, I think I've read it's to help locate the rope and stop cross loading


They are ludicrously strong compared to lightweight krabs, I've researched a bit and was surprised to see they are still on sale

In reply to cuppatea:


I sent my 10 year old pretty well used but well looked after, quickdraw slings
(slings rated at 22Kn when new - but probably well above that) to Matt Fuller who was
doing some research for Masters at Leeds(i think) and he bust them all for me, here's a bit of his report


"Five Dyneema quickdraw dogbones. Mean peak load: 19.67 kN. Lowest individual peak
load: 18.57 kN. Mean work to rupture: 173.06 J. Lowest individual work to rupture: 153.65 J."

I am pretty confident these days about older slings in good nick but well used.

In reply to cuppatea:

Could be right about the 'helping to locate the rope' part but it cant be to stop cross-loading, the crab is held completely in place by the fixed sling. Thought that was the whole point of them...

In reply to Fraser:


They're forged like that.

jk

In reply to Fraser:
I don't think DMM mention it on the website but WC do.

"and the slight 'pip' at each end helps the rope to sit correctly and load correctly."

http://www.wildcountry.co.uk/products/karabiners/helium-clean-wire/

In reply to CurlyStevo:

Cheers for that, perhaps I should resurrect mine for old time's sake. ;D

In reply to Fraser:

I think we're both right the groove helps to align the rope in the right spot