A little appreciated fact is that the internal forces generated in cams placed in downward-flaring placements can be arbitrarily high. See, for example, Vaino Kodas's explanation. Among other things, he says, "...as the angle of the flare approaches the spiral angle the forces grow very large (theoretically infinite)..."

What this means in practical terms is that cams in flaring placements are susceptible to forces that will break either the placement or the cam (or both). I'd guess that usually the placement breaks in some way and the cam is extracted by the fall, but breakage is another possible failure mode. This is a consequence of the camming geometry and is not a design failure.

This is one of the key posts in this thread. Anyone who has been reading this thread and who hasn't already clicked through to the Kodas paper, ought to do so. For those too lazy, his conclusion on cams in flares reads as follows:

"A little experimentation shows that as the angle of the flare approaches the spiral angle (tan-1µ) the forces grow very large (theoretically infinite). There will be a large compression force on the cams, a large shear force on the axle, and a large spreading force on the walls of the crack. Most likely, at these high forces, significant bending and/or deformation would take place so that the above equations would no longer be valid."

In other words, forces on cams in flared placements are much higher than in parallel-sided placements, and we ought to expect "deformation." One could reasonably expect "material failure" in even a normal cam in such a placement given a high-load fall. In a fall in which the cam was leveraged, which was clearly the case in this instance, forces would be higher and more complicated.

The Kodas finding is significant because its predictions proved out in the informal testing that Malcolm has described in which a variety of brand name cams, in off-plumb placements, failed in ways that includedwhat we've all been rather vaguely referring to as "material failure." Or rather, the inference that Malcolm, Richard, Michael and other knowlegeable folks are making is that the placement begins to shift or fail and then weird forces multiply and stuff starts to break.

I find it difficult to imagine a generalizable lab situation-- i.e., one that could become an industry standard test --that could really usefully replicate the wild variety of flare/angle/lean/leverage situations we find the the big wide world.

We've all probably taken at least a few falls onto weird cam placements that we knew to be sub-standard, but to judge from what I read on this site, the collective willingness of folks in the community to take those sort of risks has actually increased. Or maybe the ability to recognize those risks has diminished. Or both. My guess is that as more and more climbers are willing to regularly lob onto cams in weird flared placements, we are going to see more and more "exploding cams," and not just those of the "my-tweakeremployee-forgot-to-braze-it" variety.

Just for accuracy, the Link Cam stem is flexible steel cable, not solid.

--ML

k.i.k, if your self-representation is accurate, all of us are wishing you'd shut your hole.

He must have touched a nerve, cause that really didn't seem too bad. ?

Maybe you do spend too much time online and only climb 5.9.

Some of the rest of you should seriously consider your words and effect on others.

Hi Bill

Thanks for the note. To clarify one thing, I did not slam the Links. I spoke frankly of 'market fears.' What I wrote is what OP needs to hear, imo.

I wasn't that I was dissatisified in any way with the OP quick response and open analysis process. On the contrary, I am impressed, esp. when compared to CCH.

I have a long track historyt of open and vocal support of OP and their products as well, dating back ten plus years.

I also wrote the Link review here on rc.com as you may know. One of the caveats I listed in that article was that the jury was still out in terms of durability.

Well the jury is STILL out, but now the word on the street is its 9-3 voting to convict (lack of durability).

The conclusion of the OP analysis is the same as mine, only reworded. Michael said as a direct result of this failure they are going to not only create more test jigs for unusual placement and fall angles, they were also going to reevaluate the design and construction as well.

Dude I can read between the lines the same as others....

So here we have a cam at 30 degrees to the angle of fall, unable to rotate, failing completely. OK.... it begs the questions....

what about 25 degrees?
Ten?

What if the cam is nearly in line but still unable to rotate? One or two or 5 degrees?

Maybe other cams would have failed in the same spot, maybe not. I doubt many of them would explode frankly. I would expect cam deformation, for example, on any decent sized metolious or black diamond cam. I suspect many would pull out rather than exploding. Perhaps the Link held TOO WELL in this case quien sabe?

My main point here is I don't know, you don't know and most importantly, OP doesn't know.

We can all chat about the garage-mechanic-engineer days of yesteryear all we wish. In a production world of CE certs and UIAA standards, shit has got to work as advertised. This notion that 'climbing gear fails and you're a fool for thinking a cam could not explode' is total bullshit.

Cheers Bill
DMT

I haven't bought any yet, but I'm damn sure going to buy some now, if for no other reason just to help Michael and OP offset a little of the costs they incurred to investigate this incident and report the results to the climbing community.

With you on the board, I should be selling the Killfile, rather than giving it away for free.

Jay, you can't sell it or give it away for free because you are a failed pathetic excuse for a software developer.

Curt, Eat shit buddy ;-). That's the respect you've earned for your decades of experience.

I'm constantly amazed at how stupid people are so willing to make public fools of themselves by making unjustified assumptions that are so easily shown to be false.

Jay

Maybe how many do it is the amazing part!

Jay, you can't sell it or give it away for free because you are a failed pathetic excuse for a software developer.

I thought that was the median dumbass?

DMT

that's a pretty good ice burn, dingus

IQ is normally distributed, so the mean equals the median.

Do NOT fuck with a statistician, Dingus.

Jay