Article courtesy of Black Diamond.
Ever wondered exactly how strong a cam placed in “umbrella” mode actually is? Or what about the strength of your knotted slings? Don’t despair! In this QC Lab, KP and crew cover these quick hits by doing what they do best—breaking stuff! Check out the results and glean the beta that we learned through this testing process.
Thanks to all the folks that submitted ideas for this QC Lab post. We had some great ideas, some ideas we’d already done, some whacky ideas, and some sketchy ones. Instead of diving deep into one particular topic we decided to do some quick and dirty quick hits, where we’ll break some gear and talk about it without getting into too much detail. I solicited one of our crack crew of Quality Engineers, as well as our in-house photo wizard, and we spent a few hours breaking stuff in our trusty tensile tester.
In typical non-PHD level thesis style, we’re going with n=1. As in, ONE data point for each test. Even though I always give a disclaimer that this is just informational, for discussion purposes, it never fails that I get feedback from mathematicians, scientists and engineers out there claiming this data is not statistically relevant due to the small sample size. I get it. If those folks want to do a full-on scientific study on any climbing gear, that’d be awesome as the more information out there that educates new and old climbers alike, the better.
THE TESTING
We decided to look at some of the basics: Stoppers, hexes, cams, slings, and belay loops. We looked at their ultimate strength, where they broke and why. When thinking about the ultimate strength of climbing gear, it’s always good to consider the loads you usually see in the field under typical climbing circumstances, though it’s important to remember that there can be situations where loads can exceed these typical situations. Our friends over at Petzl just published a short article with some great information about real world loads. It’s worth the read to get some context while thinking about how strong gear is, or needs to be: Forces At Work in a Real Fall.
TESTING STOPPERS AND HEXES
Different size stoppers and hexes often have different strength ratings. This is because of the different size cable used, as well as the different dimensions of the stopper causing the cable to make tighter or more gentle bends. Someone asked where stoppers break, so we broke a few. We used a standard stopper jig and hex fixtures which provide a perfect stopper placement, and just used a carabiner on the other end to represent real world use.
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