How do Horizontally placed Cams Work?

Stephen Bittner wrote:The initial video and analysis are not only entirely uncontrolled and unrealistic but a mild mockery of science poised to scare budding (or gullible) climbers. This is not to say that I don't respect the time and effort expended in putting this together, but rather to suggest a bit more thoughtfulness be put into these posts. They can dramatically affect the psyche of climbers without the anecdotal experience to see through the false suggestions. In a pool of knowledge that is constantly being re-written, anything but the most stringently-studied and concretely-backed information muddles the water.

Through the whole thread here, at /r/climbing and the video comments, I've been careful about getting on anyones' case about critique of the video (constructive or non). It's partially knowing you're (me in this case) not ever going to be totally correct but more so the realization that you only invite it posting anything on the internet. chris24graham I think sums up my attitude going into this and now coming out of it; I don't regret posting it but I do regret its presentation. He's also right that I was pretty confident of what I was talking about and especially watching it now, you plainly see that over confidence, even during my valediction where I even admit that there are plenty of other factors that could be skewing what I'm seeing. But I also knew damn well before posting it that people such as chris24graham, rgold, and Christian Brachia would respond and provide answers.

If you, or anyone, is offended by the video, I deeply apologize. That wasn't my intention. I'm not trying to scare anyone, I don't have anything to gain from doing so.

I annotated the beginning the video with a link to this thread in the interest of clearing up its content. If you, or enough of you, want to see it taken down, I'll happily do so.

P.S.
I want to repost a comment I left on /r/climbing:
"I realize a lot of people are understandably caught up in the low friction setup. The purpose of the setup I used was to highlight the affect of what I'm calling the "stem angle". By lowering the friction coefficient, that affect becomes more pronounced because the forces I'm working with are significantly lower. If I were to raise the amount of friction in the system, I would need something that could put 6 - 15 KN of force and be able to reasonably gauge how much force was applied. Of course, maybe a yank can do that. Some others on MP pointed out that I should take more consideration into momentary forces (they're right). A fall would apply a tremendous force but over a period of time, not instantaneously like me yanking on pro.
It's not accurate to a real world scenario and I apologize if that's how it's coming across. It's purpose is to highlight an affect that can have real world consequences."

Also important to point out, I'm not claim the camming angle changes in the system. I used to think that but couldn't make sense of it. The realization it doesn't change is how I came about the model in the video.
I'm pretty confident that is correct.

Believe it or not, I'm still not entirely unconvinced theres an affect worth taking into consideration. chris24gram had mentioned towards the beginning of thread that I'm not taking "balance forces" (between the upper and lower lobes) into consideration (and he's right). I just need to work that out and figure out a way to test it and there seems to be some effect in my own exploration. It's just a matter of figuring out what I'm experiencing. You can always go back and watch Christian take falls to know they're working and believe me, I didn't stop placing them when I worked all this out and will continue to do so.

Again, I apologize if this is coming across as a scare tactic. See you all in Gunks!

I think the dueling videos are fun and have been part of a mostly civil discussion. Both the original video from Random and the second one from Chris have their own special flaws, the original because of potential flexing of the crack jig (already known to have produced faulty results in other tests---see mountainproject.com/v/-mast…) and the second because of the sharing of the load with the backup. Both were made in good faith by people who were trying to be helpful, and we ought to be thanking them all.

The fact is that cams do sometimes fail and afterwards we aren't sure why, and then in other cases they hold when everything we know about them suggests they shouldn't. If you've been around for a while, you've seen or heard about accidents that just shouldn't have happened. Suggesting technical considerations that might explain an unexpected failure is a good thing and is worth encouraging.

If noobs (and not-so-noobs) are scared into doubling up on shallow horizontal placements, surely no harm will be done.

How many people here who are heaping praise for Tri-cams as the preferred choice for horizontal placements have ever actually taken a big whipper on one? Honest question

rgold wrote:The fact is that cams do sometimes fail and afterwards we aren't sure why,

Rich, can you please give an example of when this has happened to you??

AndySalo wrote:How many people here who are heaping praise for Tri-cams as the preferred choice for horizontal placements have ever actually taken a big whipper on one? Honest question

+1
Or have taken a whipper in general

While I appreciate the acknowledgement of the inappropriate presentation here, the issue is bigger than that. It encompasses every piece of information and questions put forward, the topic itself, the armchair science, the lack of reliable evidence, the lack of real life examples, the guesses and suggestions of a few who are curious about a small portion (the "stem angle") of this initial inquiry. The title of this post is "Does Pro really work in Horizontals" and the question itself is unfounded.

If this were an issue that had caused cams to blow, even once, it would be worth discussing. As it stands, it is something that hasn't happened. If it isn't an issue, why is it being investigated?

"Does Pro really work in Verticals?" would be just as valid a topic to explore.

I suppose what I'm saying is- Why hold a trial when no crime has been alleged?

AndySalo wrote: Rich, can you please give an example of when this has happened to you??

Andy, I've had cams in horizontals pull a few times, and friends have added several more. A mutual acquaintence of ours has a metal plate in his head because of this. Some have been in horizontals, some have been placed straight up behind flakes (not flakes that moved in any way though). Some have been aid pieces I was sure was good and was really surprised at the bounce test. I'm not speaking of any I thought were bad when placed.

Looking back, I can sometimes hypothesize about why. Rotation was probably one of the causes. (On the other hand, I've had a blue alien rotate half out of a crack so that only two lobes were in and still catch a near factor-2 fall. Go figure.) Another cause is that some Gunks cracks flare inwards, i.e. the get bigger deeper in. Ordinary rope motions can walk the cam back, and then it can spring all the way open. It is typically much better to try to keyhole a nut into such placements, but in some cases I simply hadn't noticed the flare.

That still leaves some cases when I have no idea why the cam pulled.

Cams work very well in the Gunks because the rock is so hard and there is no surface granularity to lubricate (unless the crack is dirty). But Doug Phillips, the designer of Metolius cams, wrote,

"No matter how good a placement looks, you can never be sure it will hold. During my tests, about one in twenty good-looking placements pulled out when loaded."

Stephen Bittner wrote:I suppose what I'm saying is- Why hold a trial when no crime has been alleged?

The OP took a fall and pulled a cam, so he might have thought a crime had been committed. But that isn't really the point---the crime analogy is bad. The trick is to understand something that might get you hurt before it happens, not hold a trial afterwards from your hospital bed or the morgue.

Great post but +1 with dem tricams

No Rich, the OP did NOT pull a cam during his fall.

Thank you for some insight into cam pulling. Your anecdotes are far better than some simulation with shoddy science

AndySalo wrote:No Rich, the OP did NOT pull a cam during his fall.

Ok, then I'll just enjoy the effects of rhetorical redundancy and go with the second part of my comment. :)

Another sneaky way for cams to fail occurs if they are in a locally flared placement. In this case, it isn't a failure of friction, rather some structural part or parts of the cam fail. The reason is that flared placements raise the interior loads on cam parts with no upper bound (according to the somewhat deprecated results of the theory...). When the whole crack is flared, the issue is obvious. But cracks in featured rock can be just very locally flared right around where the cam lobes sit, and one might not notice this. I think this might be what happened in a fatal accident on Boston some years ago when the cam was pretty much destroyed by a moderate fall.

Then of course there is always the possibility that the rock, or some small section of the rock, has a coefficient of friction low enough to cause the cam to pull out. Some limestone and basalt are know to have such properties globally. In these case the jerk test should extract the cam though. Cases in point (the first is a granite horizontal):

youtube.com/watch?v=DHjNxgb…

youtu.be/-WPM1Hdwu_8

youtube.com/watch?v=MW1teH6…

youtube.com/watch?v=O9gM1J1…

youtube.com/watch?v=GQ854rw…

youtube.com/watch?v=UFUGHeq…

and comments after the route description of Hairy Interlude in mountainproject.com/v/hairy…

Not to be someone who espouses hard and fast rules, but the moral here simply seems to be: avoid having just one piece be between you and the ground.

Also when cams are placed in horizontals aren't the outer lobes supposed to be on the bottom.. that's what I was thought and everyone of your placements in the 22 min clips are "upside down" just curious as to others input

AndySalo wrote:Not to be someone who espouses hard and fast rules, but the moral here simply seems to be: avoid having just one piece be between you and the ground.

That's a good hard and fast rule to espouse if you aren't espousing rules.

I think another good general rule is that in featured rock, we ought to pay as much attention to the local geometry of cam placements as we would to nut placements; we shouldn't just jam 'em in they way we would in and IC or Yosemite spltter.

rgold wrote: The fact is that cams do sometimes fail and afterwards we aren't sure why, and then in other cases they hold when everything we know about them suggests they shouldn't. If you've been around for a while, you've seen or heard about accidents that just shouldn't have happened.

I think this is a really good take-away from this thread. You can never be 100% sure when it comes to cam placements. 99% sure is probably good enough, though, especially if you've got another piece a few feet below. A good rule of thumb is to keep at least 2 pieces between you in the hospital.

Thinking about and trying to understand how things work is never a bad thing. At worst, it's merely interesting, at best it leads to valuable practical insight. The only problem is if someone presents hypotheses and ideas as being more certain than they actually are. The OP has already owned up to doing that.

I'm fairly certain that no one here has a definitive answer for why the cam in the OP's video failed only on a downward pull. The OP tried, unsuccessfully, to explain it theoretically. Others have presented possible explanations, but none of those have been proven or even supported with much evidence. Still others have written it off as irrelevant. The only thing certain is that what happened in the video, happened, and there's no harm, and possibly something to be gained, by seeking a rigorous explanation for it.

There are several known ways for cams to fail, and reiterating those isn't what this topic was about. We all know flared placements aren't to be trusted, etc. Had this been title "What causes cams to fail?" there would have been far more interesting discussion and anecdotal examples put forth by people worth listening to.

The fact of the matter is that this wasn't an investigation into why cams fail, a noble but known topic. It was an accusation of failure without ANY applicable evidence to back it up, and that seems unreasonable and fear mongering.

Yes cams have failed, we have all seen the videos, we've likely all had it happen and for the most part we know why it happens. But until GOOD placements start rocketing out of horizontals after moderate, or even large falls, this type of pseudoscience should not assert that well placed cams in horizontal cracks are going to fail.

AndySalo wrote:How many people here who are heaping praise for Tri-cams as the preferred choice for horizontal placements have ever actually taken a big whipper on one? Honest question

I'll bite. Although at this point I'm not saying I prefer Tricams for this scenario. It would depend on the gear placing stance and the nature of the crack. Not sure if this meets your criteria, but I've fallen on a pink 0.5 Tricam EVO that was placed in a dirty upwards facing pocket. It held like a champ.

I love science, I teach physics, I love theory and experiment BUT........

The theoretical model being built is seeking to explain something that no one is observing.

Maybe the OP can weigh in, but he only questioned if the cam would hold, then proceeded to climb Carbs, fall, and then no cams ripped. Is that correct or did a cam blow?

If the theory isn't related to an observed phenomenon it isn't science. Furthermore, if it is not informing us as how to modify our cam placing behavior it doesn't help us as climbers. However, it does have the potential misinform new climbers.

rgold wrote:The fact is that cams do sometimes fail and afterwards we aren't sure why...

Really?

In my early days of climbing I didn't know why some of my cams held and others did, but after a lot of free and aid climbing I learned the nuances of proper cam placement. I no longer find that placements I deem to be "good" fail. I am not surprised when poor placements fail. However, I am surprised when poor placements hold!

If I couldn't explain why my good placements were failing I would quit climbing.