Single steel locker anchor

Heya! Long time route ticker/commenter, rare poster here.

My friend recently showed off the steel-liner carabiners on two of his QDs, reserved for bolted anchors, explaining it saves wear on normal QDs. I looked at my half-worn draws and thought I might do something similar.

So I bought a few bits of gear, but thought I should run it by ya'll before tearing the tags. Here's what I came up with:

What you're looking at, top to bottom: two wiregate carabiners, two beefy nylon slings, and a single all-steel 40 kN locker.

Is there a reason I shouldn't use this? I'm specifically wanting to use itinstead of two QDs. I know there are better anchors (quad), but I want to find out if this setup has any disadvantage (except weight) over the pair of QDs we normally rely on.

Or, if you were me, how would you use a single steel locker for a basic cragging anchor? I'm open to just using a quad, but I like this because its minimal and the slings randomly rotating around will even wear. Just weary because, you know, I've never seen one.

Ben Swrote:

Just weary because, you know, I've never seen one.

If you are weary, you should get some rest. And definitely don't drive or text.

Alright. If it makes others uncomfortable, that in of itself makes it a terrible idea. I just ordered Edelrid Bulletproof QDs, plan to use them and return the mess I posted.

But I like to learn and I'm curious. Not trolling, for reals I don't see why my weird concoction is worse than two regular ass quickdraws. But I want to see! Show me the light, and generations to come will benefit.

Two QDs provide redundancy. One steel locker does not. Issues could include: a manufacturing defect. One steel locker probably weighs more than two aluminum.

You're triaxial loading the steel carabineer. While rated for 40kn, it's not when pulled in three directions. Furthermore, the gate is not rated to 40kn. Also, your rope bearing surface is just one carabineer thick if you're top roping which doesn't help with a smooth feed. Finally, there's no redundancy. If it unscrews somehow, or you fail to screw it down and it opens, or it fails for any other reason you or your partner is ded. 

Go for it! 

If one locker is unacceptable, then why does everyone use that for masterpoints? Why is me tethered to one on a hanging belay just fine? Those redundancy and triaxial loading arguments and everything apply to those cases.

My big takeaway is don't use this because it'll freak people out. Unsarcastically, thanks all!

Ben Swrote:

If one locker is unacceptable, then why does everyone use that for masterpoints? Why is me tethered to one on a hanging belay just fine? Those redundancy and triaxial loading arguments and everything apply to those cases.

My big takeaway is don't use this because it'll freak people out. Unsarcastically, thanks all!

One locker is ok for master points because, usually, you'll be able to visually monitor it at any time to ensure that nothing weird is happening to the gate. You can't always do this while top roping.

Sure, that single steel locker is incredibly unlikely to fail even with the load concerns someone else raised, but why not go for full redundancy unless you can't? Why not add another locker? If you don't want the weight or expense of another steel locker, just use a same-sized lighter one.

We regularly trust our lives to a single bolt or a monolith, but when redundancy is an option, especially in a single-pitch environment where everyone should just be safe and have fun, why not take it?

Ben Swrote:

If one locker is unacceptable, then why does everyone use that for masterpoints? Why is me tethered to one on a hanging belay just fine? Those redundancy and triaxial loading arguments and everything apply to those cases.

No, the loads are not the same between what's happening in your photo and when using a master point. 

Keep in mind, if you're able to return that gear (which I'd be surprised) it's a total waste. Places like REI then have to destroy it because it's climbing gear with a critical application. You've got two good slings, just keep them for making alpine draws! Climb enough and you'll want them eventually anyway. 

If this is all single-pitch sport, and all you're doing on this anchor is lowering and toproping, then the force rating of your slings and biners is irrelevant, and the triaxial loading of the biner is also irrelevant. Your setup is completely unequalized, and a failure on one side will cause some extension and dynamic loading on the other side, but that's irrelevant unless both bolts are so bad that they're just waiting to blow when subjected to a slightly higher than normal force.

But that's a long list of ifs, and it seems to me like a bad idea to build a set of habits that are only safe for one hyper-specialized scenario. Just because you can get away with the triaxial loading in that scenario, that doesn't mean it's a good habit to have.

In general, the way to get a really strong anchor is not to use very stiff and strong components, which seems to be what you're trying to do. Even 6 mm nylon cord is so strong that nobody will ever break it, even in the world's hugest high-fall-factor fall. The way to get a really strong anchor is with redundancy, equalization, and no extension. The reason people use steel biners for toproping isn't that an aluminum biner will just snap, it's that they do so much toproping (e.g., guides), that wear becomes a concern, and it's cheaper to buy a steel biner than to keep replacing aluminum biners that get worn.

Incog Nicowrote:

You're triaxial loading the steel carabineer.

Where's the third axis?

What is the application here?  Is this for repeated top roping or just a single follower who will TR and clean after leader?

Jim Tittwrote:

Where's the third axis?

There is force being applied in the direction of each bolt and in the direction of the rope. If the bolts are close together the top two would start to come together but it would be more of an issue if the bolts were far apart. 

Jim Tittwrote:

Where's the third axis?

its not an axis per se, but a force vector (if you want to get technical)

Ben Crowellwrote:

If this is all single-pitch sport, and all you're doing on this anchor is lowering and toproping, then the force rating of your slings and biners is irrelevant, and the triaxial loading of the biner is also irrelevant. Your setup is completely unequalized, and a failure on one side will cause some extension and dynamic loading on the other side, but that's irrelevant unless both bolts are so bad that they're just waiting to blow when subjected to a slightly higher than normal force.

Wait, you believe the rig in OP's photo will only load one of a pair of horizontally spaced bolts??

Jim Tittwrote:

Where's the third axis?

"Triaxial" is maybe not the clearest or most precise way to say it. Here's an ascii art carabiner:

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It intrinsically has a long axis (up and down on the screen), a transverse axis (left and right), and a third axis that is perpendicular to the screen (which is normally irrelevant).

The issue with the OP's setup is that some of the force vectors have components along the transverse axis. It's weak along that axis. Because there are three force vectors acting on the biner, all along different lines, there is no way that the biner can be reoriented or reorient itself to eliminate those transverse components.

The reason the "tri" thing sort of makes sense is that this problem can only exist if you have at least three forces acting along three different lines. If there are only two forces, then normally they're going to have to be along the same line, in which case the biner will usually just naturally rotate so that the forces are longitudinal, or if not, then you can always rotate it into that position by hand. (If there were two forces and they weren't along the same line, the biner would be accelerating to one side -- this wouldn't happen with an anchor that was sitting there statically, under load.)

curt86irocwrote:

its not an axis per se, but a force vector (if you want to get technical)

Exactly.

Most of what i am reading here in the comments makes sense. I will throw in that the commercial climbing gyms in Minnesota (VE) have some of their top rope setups off of one steel locker. The steel locker is attached to the steel ceiling trusses with chain (like that used in permanent anchors). In OPs scenario, id be more worries about the bolts in the rock failing and maybe the slings failing. If im doing top roping, i will use a cordalette system with 2 steel lockers... overkill but thats the way i like it, its more about the wear on the gear anyway.  

Alright. I'm gunna engage, because science. Disclaimer: I'm not at all entertaining this anchor anymore. The steel lined quickdraws of my dreams have been shipped already (on sale at Denver Climbing Company!). Soon I will no longer envy my friend's alumina-free rope and ageless quickdraws.

Some of the arguments here are sound, but some are utter rubbish and I want to explore that.

Triaxial loading, like so many wonderful things in life, is not black and white. There are three force vectors in distinct directions: it's technically triaxial. However, consider the arguments against this mattering: the angle between the top two axes is pretty small, the carabiner is beefy with a cross-axis strength of 15 kN, and the force geometry here is entirely equivalent to a masterpoint attached to two bolts via girth hitch (which has been established as safe).

Ben Crowell and Nick Anastasi: literally all of your arguments are true for the two QD setup. It's generally accepted that two QDs are fine (though not *best*) for craggin with bolted anchors. Acceptable risk is the consensus, no fatalities is the record. If you don't do trust QDs (as a couple peeps I know), great! But part of my original question: is my setup worse than two QDs.

The single point of failure could be argued one way or the other. On the one hand, it's a single point. On the other, so are two QDs when one of them opens (seen it once). On the other other, that won't happen if you oppose properly. On the other other other, climbing involves a whole stack of single points of failure (human error, belay loop, human error, belay carabiner, human error, belay device, human error, rope, human error) and replacing two wiregate carabiners with one that can't open itself sounds dubious to worry over.

My main takeaway again: if others are going to feel unsafe on it, absofuckinglutely not. And slightly on one point of failure, this was the best response IMO:

Robert Swrote:

Sure, that single steel locker is incredibly unlikely to fail even with the load concerns someone else raised, but why not go for full redundancy unless you can't? Why not add another locker? If you don't want the weight or expense of another steel locker, just use a same-sized lighter one.

We regularly trust our lives to a single bolt or a monolith, but when redundancy is an option, especially in a single-pitch environment where everyone should just be safe and have fun, why not take it?

If that's the same Metolius steel locking biner I have, it's 15kN loaded across the gate and 18kN with the gate open, definitely beefy enough for this set up. Personally I still prefer to use two, sometimes even three Eldelrid Bulletproof biners at a top rope anchor. My reason is not for strength, but to have double or even triple the surface area for the rope to bend around in a TR setting, your rope will wear better than to have it bend around a single steel biner.