UKH

Halfnuts/superlights

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 John Kelly 09 Nov 2022

The medium/large wires come in at 6-7kn - quite a bit less than standard nuts

Has anyone any experience of falling on or testing these units - superlights/halfnuts 5- 8

In reply to John Kelly:

I have a set of both, never fallen on them. I trust the manufacturer's rating and they should hold most falls but despite this I often treat them more like RP's than proper wires. or reserve them for easy mountain day type adventures. 

I favour the superlight's over half nuts. The larger sizes (size 8, 9 and 10) are the best of the bunch and live on my standard rack, big enough to feel trustworthy and the best weight saving vs standard sizes.

 Cheese Monkey 09 Nov 2022
In reply to John Kelly:

A 6kn fall is going to be a bit of a monster I expect. I'd be more worried about injury from the fall itself

In reply to John Kelly:

The reality is that most falls will be in the sub 7kN category. That is the reason which Metolius for example only rate to 10kN rather than 14kN like DMM. UIAA regs limit impact created by the ropes stretch to 12kN so it will be exceedingly hard to ever create anything more than that unless you are falling on a static sling, which quite honestly, with the knowledge we have these days you would be foolhardy to do. Personally I use them as my main nuts, I have 2 sets as I really like them for their compactness. Would love to see some at 10kN though as it would just put your mind to rest.

 Jon Read 09 Nov 2022
In reply to John Kelly:

I've taken a fall onto a superlight #4, locked into Wrynose's finest andesite/tuff, without much rope out (5m?). All was fine, apart from my ego  

OP John Kelly 09 Nov 2022

In reply to 

Paul - yip  my thoughts exactly, it feels like clipping a micro, great for progression but I'm not gona fall on the bugger, Superlights definitely feel better than halfnuts, maybe just that extra kn

Cheese - yes the equivalent of 6-700kg hanging off the harness might ruin my day

Beardy - agree a 10kn rating would be wonderful 

Jon - real world testing, glad it worked out

Thanks for all replies 

John

 PaulJepson 09 Nov 2022
In reply to John Kelly:

I seem to remember that there's a video of James Pearson (I think on la voyage), where he snaps one in a lead fall. I think it's the number 2 green wc half nut. Could be wrong though. 

 James567567 09 Nov 2022
In reply to John Kelly:

I am interested in getting some halfnuts/superlights although at the lower end of the size range. When I've borrowed them i've found myself getting the small sizes in crucial places on ryolite - but perhaps I would be better looking at brass nuts for this?

regarding strength, i was interested to see this logbook entry regarding snapping  one of the small ones (4kN)
"As it turns out, the small WC superlights are actually only rated to 4kN; the wire snapped and I decked. Fortunately, the wire took most of the force out of the fall and I landed on my feet - so I walked away largely unscathed. Couldn't actually get the wire out, so at least the placement was good... "
https://www.ukclimbing.com/logbook/crags/wildcat-143/great_crack-53157

i am interested in how much force absorption occurs if a nut fails. i imagine alot more force is absorbed compared to the placement failing (nut pulling out intact) but have no evidence


 

In reply to James567567:

> i am interested in how much force absorption occurs if a nut fails. i imagine alot more force is absorbed compared to the placement failing (nut pulling out intact) but have no evidence

Sorry - don't really understand what you're asking here? Are you asking how much a broken wire will absorb as it breaks and reduce the impact on the next piece by? If so that's not a very easy question to answer as there are way too many variables involved...

 bpmclimb 09 Nov 2022
In reply to beardy mike:

…. not least, how much the piece has been used, and how much the wire is deformed where it enters the nut from repeated extraction by an upwards ripping motion. Single-wire lightweight pieces are particularly vulnerable to this, I’ve found.

OP John Kelly 09 Nov 2022
In reply to James567567:

That's a great logbook entry thanks for the link

OP John Kelly 09 Nov 2022
In reply to James567567:

That's a great logbook entry thanks for the link

Brass nuts - black diamond offset micros seem to fit everywhere but hard to get hold of

 bpmclimb 09 Nov 2022
In reply to paul_the_northerner:

> I have a set of both, never fallen on them. I trust the manufacturer's rating and they should hold most falls but despite this I often treat them more like RP's than proper wires. or reserve them for easy mountain day type adventures. 

There's a big difference though, even if the rating is similar, and that's the size of the placement, the contact area with the rock. I definitely treat halfnuts/superlights more like "proper" runners, especially the larger ones, than micros/RPs where arguably the biggest hazard is them ripping out of the placement rather than snapping - although I know they can and do snap.

 James567567 09 Nov 2022
In reply to beardy mike:

Yes - how much will marginal gear slow you down.

Marginal either because it is a placement which will rip out or because the wire will snap.

Some discussion I have seen suggests that once the rated load is exceeded the wire will fail without really removing any force from the fall. But in the logbook I quoted, the author described that even though the wire failed it absorbed enough that he decked relatively gently. I also hear people say 'it'll slow me down at least' but I was wondering how true that is.

I suppose it is just a typical force-time graph on the top runner in a climbing fall, upto the point at which the yield strength is exceeded... + a little bit for deformation.  https://www.cs.cmu.edu/~cline/Climbing/fall.html

The momentum it removes would depend on how sharp the curve is upto the point of failure. Hence, the suggestion to use screamers here to soften the curve: https://www.andy-kirkpatrick.com/articles/view/ma

For Dave Mac, marginal gear is apparently more about increasing the chances of catching the fall outright
youtube.com/watch?v=KJWAzUOvDEI&t=702

In reply to James567567:

Well that's going to depend on all sorts off things. Wire strength is one aspect, state of that wire, strength of the rock around the placement, the rope you use, the catch you belayer provides, the number of runners and the angle the rope makes through them (I.e. friction) the surface area of the nut (I.e. transmitted pressure and induced stress within the rock), and the length of the resultant force i.e. how much momentum will be built up before hitting the next piece. Ie too many variables to make a meaningful statement. Quite honestly I am dubious about screamers vs a soft catch or a low impact force rope. There are so many ways to mitigate impact on your top runner that I'm not convinced that you need to go to the bother of specialist peak force reduction runners. Maybe on ice it makes sense, but you've got to be doing something scary in the extreme to make it worthwhile. And even then I reckon you've got to seriously question whether the energy expended placing it versus any added safety margin (real or perceived) is worth the loss of concentration etc. I don't know... I don't climb hard enough to make these things worthwhile? Personally I'd rather place two pieces and use a double rope, or stack the placements with a sacrificial placement to somewhat reduce the impact and direct the line of force in the optimal direction.

 C Witter 09 Nov 2022
In reply to John Kelly:

It's quite worrying to have two reports of the 4kn wires snapping whilst catching a fall... Most of my IMPs/Swedges are 6kn, or at least 5kn. So, with the smallest sizes we're talking something weaker than an RP.

I really rate the size 3 and 4 superlights/halfnuts though: they're so good for keying into difficult placements and rated to 6kn, which is a bit more reassuring. I've not fallen on them yet, but it's a matter of time I suspect. Will report back!

7kn is the same as a no.1 Wallnut and I've definitely caught a massive whipper taken by a friend onto a lonely no.1 (on The Go Between (E2 5c). A lot of other gear, e.g. microcams, are also rated to 7kn, including for crossloading carabiners. I suspect we would have heard by now if 7kn was too weak and you can let your mind rest easy.

OP John Kelly 10 Nov 2022
In reply to C Witter:

I feel pretty comfortable 7kn and above -as you say rock 1 pretty reliable depending on the placement 

I think when you get down to 4kn, you need a bit of rope out, a nice straight rope run (half rope, well extend), and a backup plan

 MischaHY 10 Nov 2022
In reply to PaulJepson:

> I seem to remember that there's a video of James Pearson (I think on la voyage), where he snaps one in a lead fall. I think it's the number 2 green wc half nut. Could be wrong though. 

As far as I'm aware this one snaps due to the wire running over an edge. La Voyage follows a flake/seam with a rounded edge and as far as I remember the wire runs over this edge and shears. 

 elsewhere 10 Nov 2022
In reply to James567567:

The metal wire snapping probably doesn't absorb much energy as it's specified to be strong rather than stretchy. The rope on the other hand is designed to be stretchy so as the tension builds up to be enough to snap the wire, the rope absorbs loads of energy. 

When the wire snaps, the rope is no longer tight, it goes "twang" (tiny amount of sound energy), it flails about (some loss due to air resistance?) and the energy is dissipated mostly as heat in the rope (friction between fibres?).

Hence broken wire is still a lifesaver as energy dissipated by something other than the breaking of bones.

 Graeme Hammond 10 Nov 2022
In reply to John Kelly:

I belayed a friend who fell off a route a Pembroke and the red superlight he had in as his runner snapped, not a particularly hard or big fall from memory so we were a little surprised. I suspect the reason for the catastrophic failure of the wire was that it had been damaged previously, either in other falls or the wire being abusused by ripping nut upwards to remove it in other placements but not inspected afterwards. This method of removal, something that was advocated recently, is particularly damaging to more delicate wires and should be avoided at all costs.

Following this incident I carefully inspected all my wires and noted one wire that looked good but when bent at the base of the nut it was apparent that many of the wires were actually broken. Therefore use them but inspected regularly as the lower beaking strength could potentially be more easily exceeded if they are damaged compared to a higher rated nut.

Post edited at 09:14
 elsewhere 10 Nov 2022
In reply to Graeme Hammond:

Hmmmm. My rule of thumb is "gear does not break" but I need to add "but inspect bent wires for broken wires".

 Jon Read 10 Nov 2022
In reply to Graeme Hammond:

> ... wire being abusused by ripping nut upwards to remove it in other placements but not inspected afterwards. This method of removal, something that was advocated recently, is particularly damaging to more delicate wires and should be avoided at all costs.

Any second that fails to use a nut-key to remove my wires gets to know about it pretty quickly! 

1
 C Witter 10 Nov 2022
In reply to Jon Read:

> Any second that fails to use a nut-key to remove my wires gets to know about it pretty quickly! 

That we do!

 C Witter 10 Nov 2022
In reply to Graeme Hammond:

That's quite worrying! Do you remember where the wire snapped? At the clip-in point or below the head?

In reply to John Kelly:

To add to the frayed wire comments, it is worth noting that ANY junction where the cable goes from being supported to unsupported causes a stress raiser. So for example with a silver soldered nut, where the wire exits the nut is vulnerable. The same applies to crimped wires exiting a cam stem termination. The issue is that there is no strain relief (like you would have on a plug) so the wires to the outside of the bend in the cable are stressed more than on the inside. Normal nuts don't suffer from this issue because the wire rope is free to move in the nut so the stress riser dissipates along the cable. Hope that makes sense? I guess it's a quid pro quo - it's small gear which will save your life but you need to take care of it.

 Graeme Hammond 10 Nov 2022
In reply to C Witter:

> That's quite worrying! Do you remember where the wire snapped? At the clip-in point or below the head?

It broke at the base of the wired, the nut was left in the route, I think my partner removed that but it was lost.

Hopefully this link works and shows the wire after the fall

https://drive.google.com/file/d/1zQcfBvU-uPTf2mX5Hp6NnCisjEzK39_X/view?usp=drivesdk

 C Witter 10 Nov 2022
In reply to Graeme Hammond:

Thanks for your explanation. Unfortunately,  the link doesn't work for me and I couldn't quite understand your answer. It broke the wire loop you clip into? Or, else it broke where the wires go into the nut?

If the former, I would think the problem was the strength of the wire. If the latter, I expect it could be wire damage.

Either way, I'm reassessing using superlights! :0

 Graeme Hammond 10 Nov 2022
In reply to C Witter:

I think I've changed to link for anyone to view now. 

It broke where the wires go into the nut

1
 Rick Graham 10 Nov 2022
In reply to Graeme Hammond:

> I think I've changed to link for anyone to view now. 

> It broke where the wires go into the nut

No surprises  there then.

It's just a heads up to be careful that the likely load is in line with the nut especially with soldered or crimped wires. Hardly an issue with swaged loops.

Regarding the big whip, bear in mind that it's only the last flex out of many that finally breaks the wire strand. Often damage is invisible until a fracture. 

Edit. Just to add I often only climb with 1 -4 half's,  set of superlight offsets and a few cams on short pitches. So quite a fan but aware of potential issues.

Post edited at 14:16
 C Witter 10 Nov 2022
In reply to Graeme Hammond:

Thanks

 elsewhere 10 Nov 2022
In reply to Graeme Hammond:

> It broke where the wires go into the nut

YIKES!!! That photo is scary to see.

Post edited at 18:18
 C Witter 24 Nov 2022
In reply to John Kelly:

p.s. It seems Alex Moore and Robbie Philips also broke a no.5 halfnut on The Long Hope! Quite a lot of broken halfnuts...

 David Coley 25 Nov 2022
In reply to John Kelly:

Watch the film on climbing the long hope route

 CMcBain 08:37 Fri
In reply to David Coley:

I use super lights a lot, previously WC ones but now the DMM equivalent. They often fit in placements far better than a regular nut. I would rather have a bomber low kn placement than a placement that seems dubious albeit with a higher kn rating (if it holds).

It’s worth inspecting the super lights regularly, I was pretty horrified inspecting my old ones to see that all of them had snapped wires that were really well obscured. The weak point seems to be where the wire goes into the hole in the top of the nut (not the soldered end). This is where they get kinked getting placed/removed. Given the low margins on these nuts, a couple broken wires could make them fail at low loads

Interestingly I wonder if that’s what happened to Robbie on the long hope. 

 jezb1 08:51 Fri
In reply to John Kelly:

I guess my question is: Would you rather have a sinker half nut placement, or a crap regular nut placement?

I know some people will use them to be lighter, I tend to use them to give a different profile option to regular nuts though, any weight saving being a bonus.

In reply to C Witter:

> p.s. It seems Alex Moore and Robbie Philips also broke a no.5 halfnut on The Long Hope! Quite a lot of broken halfnuts...

I had a quick chat with Robbie and looked up the ratings on the nuts. Both were rated at 5kn which would seem to be OK, but one of the mitigating factors was the use of the Edelrid Swift Protect half ropes which are rated at 7.3kn as a half rope compared to 5.5kn for an opera half. That's quite a substantial difference. I'm not sure if Alex retied into the end of the rope that Robbie had just the fall on, which would have reduced the impact somewhat.. Even without that, a rope that increases the potential impact force by 30% should probably warrant some thought about the protection being used. 

 C Witter 16:16 Fri
In reply to jezb1:

I agree somewhat. But, I recently decided to replace quite a few nuts with superlights and... after all the stories I think I will go back. I've a trip in mind where I'm thinking about leading on a single rope with a higher impact force (8.7kn).... Will probably leave the no. 3 and no.4 halfnuts on, though, for the fiddly placements. I never trusted the no.1 and 2 (4kn)... I have stronger (8kn) micronuts in roughly the same sizes.


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