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maldaly


Jan 4, 2008, 4:09 PM
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Re: [baja_java] Link Cam Report [In reply to]
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On a further note, our "bad placement" tests were in parallel-sided cracks. It looks like the situation on the Ski Track was way, way worse, with one cam fixed and unable to rotate and the other coming free. Don't know if I could simulate this in our fixture but it's almost a moot point.

Further to some of the other comments, I can break most carabiners with my fingers by pressing sideways on an open gate with my thumbs. (Okay, so I don't really "break" the carabiner but I can the the gate to move sideways enough to bypass the nose, rendering the 'biner into a weak, expensive aluminum hook). Does that mean that these carabiners are bad? I hope not! It's simply an illustartion of how a relatively minor side load can tweak an open gate. The lesson is to make sure you gates stay closed, just like the OP cam lesson is to be sure that if they can rotate that they won't rotate into a fixed position or a position of weakness.

Climb safe,

Mal


billcoe_


Jan 4, 2008, 5:21 PM
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maldaly wrote:
....I can break most carabiners with my fingers by pressing sideways on an open gate with my thumbs. (Okay, so I don't really "break" the carabiner but I can the the gate to move sideways enough to bypass the nose, rendering the 'biner into a weak, expensive aluminum hook). Does that mean that these carabiners are bad? I hope not! It's simply an illustartion of how a relatively minor side load can tweak an open gate. The lesson is to make sure you gates stay closed, just like the OP cam lesson is to be sure that if they can rotate that they won't rotate into a fixed position or a position of weakness.

Climb safe,

Mal

I tried to say this earlier, but this was better said.

Got the call, someone who has posted on this thread bought a link cam and wants to break it! Maybe if I just show up and provide enough alcohol I can prevent this wanton wastage of good gear? (thats my inner gear whore and childhood poverty speaking)

I'd love to develop a pull test device. I have way too much money in the bank but no technical skill or knowledge to speak of...who's near that wants to jump into this pool?

Where the f**k is Ed Leeper when you need him most?

Oh....I know someone who I can call ...Andrew Trzynka!


healyje


Jan 4, 2008, 6:28 PM
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Re: [billcoe_] Link Cam Report [In reply to]
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maldaly wrote:
...just like the OP cam lesson is to be sure that if they can rotate that they won't rotate into a fixed position or a position of weakness.

Mal, I would agree IF they are going to be allowed to rotate - which I think is explicitly a bad idea - nothing should obstruct the complete rotation. The other issue is how textured the surfaces are the cam is rotating against - there's a big difference between a crack in the Creek and one in JT or Vedauwoo.

So, I just got back from buying a Link Cam for Bill and I to bust up. And, Mal, true, you can break things fairly easily with lateral loads and these linkages may be that sort of deal (I think so). The difference here is all biners operate basically the same - cams, however - thanks to guys like you - now display more diversity of design. My point isn't that the Link Cams are in any way bad, but rather you have a responsibility to take the delivered product design constraints into consideration when you pull one off your rack.

My view of the problem with many of the attitudes expressed in this thread is they are out of touch with reality, but in opposite ways. One camp basically says, "if I can buy it, and it has springs and a trigger, then gosh darn it, it better perform exacly like any other cam - and I'm going to obliviously use it that way". The opposite camp says, "oh my god, one broke! Recall them all, it's not a safe. The engineering and design is deficient!". I'm saying both views are misinformed and extreme, regardless of how many folks here hold them. My main point is this is an innovative cam both in design and materials - and - the delivered product has obvious limitations that, if you aren't prepared to acknowledge and work within the constraints imposed by those limitations, then you shouldn't buy or use them.

With all that prelude, here's the victim. And to be clear, I'm not after engineering results from near-perfect test jigs. I simply want to see, and feel, just how easy it is is to break these cams lobes and linkages. Maybe Bill and Andrew will devote one to more formal or on-the-rock testing, but that's not my objective for this one. We'll video the tests and post up the results when we're done - so standby.

[ Note: All that said, upfront and regardless of any results, I want to state explicitly and categorically that I personally have no qualms whatsoever using, or falling on, an appropriately slung Link Cam in a clean placement. ]




(This post was edited by healyje on Jan 5, 2008, 1:31 AM)


Partner baja_java


Jan 4, 2008, 6:30 PM
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billcoe_ wrote:
Got the call, someone who has posted on this thread bought a link cam and wants to break it! Maybe if I just show up and provide enough alcohol I can prevent this wanton wastage of good gear? (thats my inner gear whore and childhood poverty speaking)

and what exactly would that accomplish, if they still don't understand the forces and mechanisms that are likely involved? god knows they've been linked enough

you don't need to buy a new cam and try to break it in order to understand what likely happened. i fractured my cam in a way i absolutely did not expect, very much to my surprise. i've had that Link Cam for over a year, climbed all over CA with it, and Utah, and CO. i wish it's still unbroken and functional and could continue to be so very useful. but what happened did help me understand the breakage scenario better. like to see what Omega Pacific will make of it too


healyje


Jan 4, 2008, 6:38 PM
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baja_java wrote:
...and what exactly would that accomplish, if they still don't understand the forces and mechanisms that are likely involved?

Understanding the forces involved is exactly what I'll be after - and not in a quantitative way - but rather an old school, what's-it-take-to-break-one sort of way. The mechanisms are clear both of the device and how it will be broken; no rocket science there.

In reply to:
i fractured my cam in a way i absolutely did not expect, very much to my surprise.

Well, post up my man - exactly how did you break it? I can't think of any reason whatsoever for secrecy in the matter.


Partner baja_java


Jan 4, 2008, 6:56 PM
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not secrecy. simply more productive to let Omega Pacific do their thing first. i've questions for them too. we both like to get a good understanding of what happened

healyje wrote:
Understanding the forces involved is exactly what I'll be after - and not in a quantitative way - but rather an old school, what's-it-take-to-break-one sort of way. The mechanisms are clear both of the device and how it will be broken; no rocket science there.

do you really not know what it would take to break a cam, any cam? they're not indestructible, you know, even the parts and pieces

and no, none of this is rocket science. trust me, it's not


healyje


Jan 4, 2008, 7:03 PM
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I've broken lots of them over the years - from original friends on - I simply want to break one of these.


Partner baja_java


Jan 4, 2008, 7:16 PM
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well, it is important to get to break what you want when you want and how you want and for no real good reason if that's what you want. i envy the true freedom with which you live your life


murf


Jan 4, 2008, 7:28 PM
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healyje wrote:
I've broken lots of them over the years - from original friends on - I simply want to break one of these.

Joe,

I've read a ton from you, all 'bout back in the day, SoIll or whatever, doin' it, puttin' it up on lead.... Blah, blah, blah....

Exactly how many cams have you broken?
What were the exact circumstances?
What brands?
Pics?

Specifically in as much detail as possible please.

In case you were wondering, I've never broken a cam, a carabiner, or any other climbing gear that I can think of, bare hands or otherwise.

-Murf


maldaly


Jan 4, 2008, 8:09 PM
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healyje, I'm with you all the way here. I love the analogies to the rigid friends. We all knew they had a weakness, yet we climbed and placed around those while advancing standards in amazing ways. We just need to remember that with all the various designs of cams available out now that we STILL need to place them with consideration for their their design limitations/advantages.

Can't wait to hear the results of your thumb test.
Mal


billcoe_


Jan 4, 2008, 8:20 PM
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maldaly wrote:
healyje, I'm with you all the way here. I love the analogies to the rigid friends. We all knew they had a weakness, yet we climbed and placed around those while advancing standards in amazing ways. We just need to remember that with all the various designs of cams available out now that we STILL need to place them with consideration for their their design limitations/advantages.

Can't wait to hear the results of your thumb test.
Mal

Exactly Malcolm, but I do have a Murf-like feel about this in that it doesn't duplicate what the average climber is looking at vis a vis a fall on one in a slanted and or slanted/flaring placement.

Meantime...back at the ranch...the video camera is warming up. I'd like to bring over one of my gold Link Cams (*cough*gearwhore*cough), and if I cannot talk Healyje into breaking mine and giving me his new one, at least visually compare it to the current one to ensure apples to apples.

I've known JH long enough to know that often my perceptions and belief of what is being said and done are often different than what is the actual reality. Dude is about 2 steps deeper or beyond where most of us are thinking.

.....See, and back then I thought 5 years in college was enough. Hrumph.

Can't wait, probably going skiing tomorrow afternoon.....AM perhaps, or maybe Sunday sometime?

Take care all...


healyje


Jan 4, 2008, 8:55 PM
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baja_java wrote:
well, it is important to get to break what you want when you want and how you want and for no real good reason if that's what you want. i envy the true freedom with which you live your life

Well, it is important to get think that there is nothing to learn when you don't want to learn anything and for no real good reason if that's what you want. I envy the true freedom with which you live your life.

Clearly, there is nothing for you to learn from anyone breaking a cam but you - but then when you operate with that breathtaking air of mystique there really is nothing anyone can learn from you breaking a cam. And "more productive"? That's flat out complete bullshit.


healyje


Jan 4, 2008, 10:44 PM
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murf wrote:
Blah, blah, blah....
My favorite part so far...

murf wrote:
Exactly how many cams have you broken?
More than four, less than ten, not sure to be honest, it's been thirty four years this month.

murf wrote:
What were the exact circumstances? What brands?
Well, let's see - all falls on placements - I suppose this will be my first attempt at finger destruction. Let's see, two in flares just by coincidence - one downward vertical (original friend / Eldo) and one odd upward (original Camalot / Eldo). One rotating past, you guessed a large crystal / Cathedral (Early HB). One over an edge (original friend / Gunks, of course...). That's what, four? One cam lobe split from axle (Wired Bliss / ). Two blown cam stops (Early Metolius FCUs / Smith & Beacon). So seven altogether I guess.

murf wrote:
Pics?
Ha, ha! Pics! Well, all were pre-digital, pre-Internet and all were my fault - no pics were ever necessary. I wish I had pics of the Friend that blew in the downward flare in Eldo - a #4 I think that seemed more or less perfect in every way outside of a slight flare. But it absolutely disintegrated, as in all four lobes shattered into small pieces; stem and axle stayed intact. Got caught by a pink tricam right below it. Didn't even find more than about half the fragments. The first gen Camalots were basically dangerous junk and I still don't like the design of any generation since. I ignorantly broke a rigid stem over an edge at the Gunks right when I first moved back East - duh, but I was pretty lit up mycologically speaking. The split lobe and blown stops were on small cams in dirty placements where the piece drug out snagging on stuff on the way and inverting. A couple of big falls, but I tend to thoroughly back things up when I have any doubt at all so most weren't.

murf wrote:
In case you were wondering, I've never broken a cam, a carabiner, or any other climbing gear that I can think of, bare hands or otherwise.
I don't know you murf, for all I know you're one of those 'must not, or strive not to, ever fall' folks - lots are, but it's never been a philosophy I subscribed to and do fall a bit I guess. I'm pretty hard on gear in general and also mod quite a bit of it.


Partner rgold


Jan 4, 2008, 10:51 PM
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murf wrote:
Looking at the pictures of the placement, my gut feeling is that something additional happens with multiple of the lobes touching.

Hoo boy. It is complicated. I would think that the cams were designed with parallel placements in mind and so with the assumption that cam segments on either side would be symmetrically deployed. When this doesn't happen, there could be loads on the links and ultimately on the final arm that connects the top link to the axle that weren't anticipated in the design. (For one thing, once the links start to open up, the shape is no longer a single logarithmic spiral and so the elementary vector analysis changes.) Combine this with the higher loads resulting from flared placements and perhaps you have conditions for breakage.

I know this type of speculation doesn't come close to satisfying DMT's criteria, but I'd be wary of placing these cams in a way that results in asymmetric cam contact. (I think I've read about the potential for such contact as a useful feature...) Does OP have a position about such placements?


Partner rgold


Jan 4, 2008, 11:01 PM
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healyje wrote:
Let's see, two in flares just by coincidence...the Friend that blew in the downward flare in Eldo - a #4 I think that seemed more or less perfect in every way outside of a slight flare. But it absolutely disintegrated, as in all four lobes shattered into small pieces

Hmm. Coincidence?


healyje


Jan 4, 2008, 11:19 PM
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billcoe_ wrote:
Exactly Malcolm, but I do have a Murf-like feel about this in that it doesn't duplicate what the average climber is looking at vis a vis a fall on one in a slanted and or slanted/flaring placement.

Bill, I guess this is the heart of it. What the average climber is looking at if they misuse a Link Cam - either by allowing stem leverage over an edge, bad orientation, and/or rotation due to poor slinging - is significant lateral forces applied to the cam lobe assemblies. Any and all of those three scenarios are easily capable of generating such undesirable loads. That's not fantasy, speculation, or wild ass guessing - just fact.

The only real question is how robust the Link cam lobe assemblies are in the face of those potential hazards - can you in fact treat them just like an unsegmented cam? If I can break them easily then the answer is, no, you can't treat them like an unsegmented cam. Because where an unsegmented cam would likely stick or pull, these might very well break.

Frankly, I find it all a bit of an odd position to be in. Attempting to show the weakness of a cam design I fully support the marketing of. But, I'm doing it in the hope people will consider taking a bit more personal esponsibility for how they employ such gear. Because if folks can't do that, it basically means we are collectively more interested in 'foolproof' commodity products than innovative ones.


healyje


Jan 4, 2008, 11:27 PM
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rgold wrote:
Hmm. Coincidence?

I meant coincidental to the topic. Nether was flared across the lobes side-to-side, but rather flared up and flared down - the cam lobes where in quite symmetrically. The upwardly flared slot was oddly pebbled one side. It didn't rotate across it, but rather slipped off one of them I think and set up some bad juju.


notapplicable


Jan 5, 2008, 10:56 AM
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healyje wrote:

...Frankly, I find it all a bit of an odd position to be in. Attempting to show the weakness of a cam design I fully support the marketing of. But, I'm doing it in the hope people will consider taking a bit more personal esponsibility for how they employ such gear. Because if folks can't do that, it basically means we are collectively more interested in 'foolproof' commodity products than innovative ones.


I say break em, no justification needed. At the least it will be an interesting experience and a fun way to pass the time. Obviously it would be a bit more helpful if you were able to register the actual forces needed to cause a failure but I definintely think there is something to be said for simply having a "feel" for the limitations of the gear used to safeguard ones life. Please post the pics and video when you finish destroying stuff.


mheyman


Jan 5, 2008, 11:41 AM
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I have seen the Kodas link before. The ďpaperĒ isnít long and the math not ďtooĒ difficult, but previously I looked only at the first pages and blew it off only as detail in cam angle design.

I find the last two pages pretty scary. I donít think it is intuitive, and I donít think many people are aware of it! If I understand this properly then I am surprised we donít see more cam failures due to this placement geometry, and I understand why RG so strongly prefers passive pro. Is my understanding that flaring cam placements are too be strongly avoided, not because a piece may pull, but because it can easily generate extremely high forces that can destroy the unit.

This failure mode is common to all cams, and it does not seem that those faulting the LC cam at this time understand this. I havenít seen OP blame it solely, so kudos to them for being conservative in testing other possibilities too.


(This post was edited by mheyman on Jan 5, 2008, 3:11 PM)


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Jan 5, 2008, 11:56 AM
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healyje wrote:
Well, it is important to get think that there is nothing to learn when you don't want to learn anything and for no real good reason if that's what you want. I envy the true freedom with which you live your life.

Clearly, there is nothing for you to learn from anyone breaking a cam but you - but then when you operate with that breathtaking air of mystique there really is nothing anyone can learn from you breaking a cam. And "more productive"? That's flat out complete bullshit.

i'm going to clear up a few things with Omega Pacific first, Joseph. this is that important. i believe it's the responsible thing to do. sorry you find that unacceptable, and felt it necessary to let loose with that speculative angst of yours

Dingus and Jay and others have already pointed out how ridiculous that one-look analysis of yours is, regarding the structural integrity of the linked lobes. i know what intuition you're basing that on, but that's if you're comparing a segmented lobe with all pieces made of aluminum versus a one-piece aluminum lobe. the Link Cam design is different, which has a steel inner link, a steel middle link, and an aluminum outer link. and in the connection between the steel and the aluminum segments, the connecting flanges are two outer steel ones and one thick aluminum one in the middle. the obvious design flaw you're screaming and accusing everyone else to be in denial about seems like the kind of critical design issue that would be addressed early in the cam's development process. one look at this segmented cam lobe, all i can tell you is that it's likely stronger than an all aluminum segmented design, and may well have the strength comparable to a one-piece aluminum lobe, and that a lot of thought has gone into its design. other people do have some idea though, about its breaking strength, based on informal test results

in a discussion like this, some people seem to think the more speculation there is, the better. and some are way far on that extreme, who needs to not only shout out their speculation over everybody else's but also needs to demand its universal acceptance when everyone knows damn well it's just speculation. it's almost psychotic

i'd rather keep the speculation minimal. i personally don't think dirtme and i will be the only two ever with actual first-hand details of this kind of breakage. labs at Omega Pacific and Trango and others probably will too, at some point. and with that, in time, much of the overzealous speculation would prove a total waste of time, as in unproductive

however good i feel now about my grasp of what i think had happened to the two cams, i'm just honest enough to admit to myself that some of those thoughts are sound and some are speculative. so far i'm the only one who has seen my fractured cam, before it was immediately express shipped to Omega Pacific (arrival monday). i think it's very reasonable for me to want to have other eyes at OP look at the fracture and see what they think too, to confirm my thinking before and instead of just throwing piecewise details out there and let the speculations run wild. i also want to be precise about what i say, unlike some people. i don't believe i'm posturing for the moment. sorry you can't see others in a better light to give them the benefit of the doubt. besides, i've already given you the basic info: another fracture has occurred, this time with a fairly low load. and i've also re-quoted some info here and elsewhere about the sound structural integrity of the linked lobe design

i didn't set out to break a Link Cam to learn something. i was simply using mine to check out placement variations and to look at the rotational behavior, to satisfy my own curiosity at first, until someone asked which flared pod and another asked about the pro. but no, not to break it. break yours if you want. i didn't say one can't break a cam and learn something. what i was getting at is that the relevant concepts involved have already been discussed, time and again by multiple people

that though doesn't mean i agree fully with them. this isn't some debate team contest. some of you seem very adamant that the cause of failure has got to be one or the other, either the rotation and resulting leverage, or the force amplification. i actually think it might well be both. for example, Vaino defined his flare as straight lines to keep the presentation of his formulation simple. the set-up Malcolm has at Trango models the flares using flat plates. the flare inside the Left Ski Track pod is best defined by a curved surface, like that of one half of an ellipsoid, so that if a cam rotates from side to side, like when the set of lobes on one side pulls out, the other set can pivot into another direction that might well have a significantly different flare profile that could be better or a lot worse, especially if the cam is jammed up against the back corner of that ellipsoid. so i think it's possible that a rotation can further "amplify" a flare-induced force amplification

anyway, as some have voiced time and again, users of cams should really understand how cams work. entrusting your life to a piece of gear the workings of which you don't fully understand, that's kind of crazy


jt512


Jan 5, 2008, 12:38 PM
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mheyman wrote:
I have seen the Kodas link before. The ďpaperĒ isnít long and the math not ďtooĒ difficult, but previously I looked only at the first pages and blew it off only as detail in cam angle design.

I find the last two pages pretty scary. I donít think it is intuitive, and I donít think many people are aware of it! If I understand this properly then I am surprised we donít see more cam failures due to this placment geometry...

That was my first reaction, too: If this is as bad as it sounds, why aren't these failures happening so frequently that all are aware of the danger? I propose two possible reasons. The first is that the maximum force occurs when the flare is the greatest angle that the cam will hold; any larger, and the cam won't stick in the crack at all (according to Kodas). So placements in flares close to this angle will be tenuous ones that climbers will avoid. The second (possible) reason is that Kodas's analysis assumes that the angle at which the cam lobes contact the rock is a point, a mathematical construct that simplifies the analysis. In reality, the cam lobes would contact the rock over a small range of angles simultaneously. Perhaps this spreads the total force over the contact area, reducing the likelihood of failure - I'm just hypothesizing. This is definitely above my pay grade.

Jay


Partner rgold


Jan 5, 2008, 1:28 PM
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In reply to:
If I understand this properly then I am surprised we donít see more cam failures due to this placment geometry...

In reply to:
If this is as bad as it sounds, why aren't these failures happening so frequently that all are aware of the danger?


Reasonable questions indeed. In order for the forces to get high enough to destroy a cam, the cam has to stay in place. But high forces have other effects that change the original analysis. First of all, the high load on the crack walls can create surface crumbling, which would decrease the coefficient of friction perhaps enough to allow the cam to pull out.

There is a second mechanism of failure that isn't part of Kodas' analysis, although he mentions it as an outcome that invalidates his equations, and that is elastic (and ultimately plastic) deformation of the cam faces leading to shear yield. The cam flattens out under load and the material yields to shear forces even if the coefficient of friction is enough to keep a non-deforming cam in place. Dave Custer has an account of this at his MIT site.

To continue a line of speculation, which I do not see as harmful as long as it is clear what it is, my take is that the increased forces in flared placements probably result in the cam pulling out most of the time, especially in the smaller sizes, for which the shear yield threshold is lower, and that much rarer situations in which, for some reason, these failure thresholds turn out to be abnormally high are the only ones that result in cam breakage. Link cams in flared placements might have multiple segments in contact with the crack, which could spread forces and so raise the level needed for shear failure. The inner steel links also have higher shear yield thresholds, and so could allow higher forces to build. Both of these conditions would raise the probability of a link cam breaking in a situation in which a regular cam would pull out.


Partner baja_java


Jan 5, 2008, 2:51 PM
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rgold wrote:
murf wrote:
Looking at the pictures of the placement, my gut feeling is that something additional happens with multiple of the lobes touching.

Hoo boy. It is complicated. I would think that the cams were designed with parallel placements in mind and so with the assumption that cam segments on either side would be symmetrically deployed. When this doesn't happen, there could be loads on the links and ultimately on the final arm that connects the top link to the axle that weren't anticipated in the design. (For one thing, once the links start to open up, the shape is no longer a single logarithmic spiral and so the elementary vector analysis changes.) Combine this with the higher loads resulting from flared placements and perhaps you have conditions for breakage.

Richard, Murf, seems a cam lobe segment can cam into the rock only when they're fully supported by the barrel of the axle, as in only when it's furled up around the axle, as in the unfurled ones behind that (an outer one) can maybe touch the rock but not cam into it

a stretched out line of links like that can become a stiff moment arm too if the length of that is torqued sideways. that's what some have observed


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Jan 5, 2008, 3:10 PM
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jt512 wrote:
mheyman wrote:
I find the last two pages pretty scary. I donít think it is intuitive, and I donít think many people are aware of it! If I understand this properly then I am surprised we donít see more cam failures due to this placment geometry...

That was my first reaction, too: If this is as bad as it sounds, why aren't these failures happening so frequently that all are aware of the danger? I propose two possible reasons. The first is that the maximum force occurs when the flare is the greatest angle that the cam will hold; any larger, and the cam won't stick in the crack at all (according to Kodas). So placements in flares close to this angle will be tenuous ones that climbers will avoid.

i think that's mainly why, Jay. those tenuous placements, often with the flare facing downward, are placements you'd avoid anyway, though for a different reason, that the cam would look like it might just fall out. why i don't need to climb with a protractor on the rack


healyje


Jan 5, 2008, 5:42 PM
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baja_java wrote:
i'm going to clear up a few things with Omega Pacific first, Joseph this is that important i believe it's the responsible thing to do sorry you find that unacceptable, and felt it necessary to let loose with that speculative angst of yours

I have no angst around the issue, speculative or otherwise. Again, whatever the rationale you have for not being completely upfront about what happened to your cam is entirely counterproductive - you only increase speculation doling out your tidbits. The way to stop speculation is to simply state what happened in clear, concise terms.

baja_java wrote:
Dingus and Jay and others have already pointed out how ridiculous that one-look analysis of yours is, regarding the structural integrity of the linked lobes.
Dingus and Jay are entirely welcome to their opinions. But as far as I'm concerned it's simply a form of group-think combined with a blinding consumerism that says climbing, and climbing products are now well-integrated into suburban life. Hey, look at one of damn things - or, for those more anally inclined - measure the thickness of one of the link flanges on either end of a middle cam lobe segment, surely one of you has a micrometer. There are four such flanges on each of the four segmented lobes; sixteen in all. That's sixteen thin flanges of metal which can fail compared to zero on a conventional unsegmented cam. Now, you and others may have the sort of unquestioned faith in modern engineering and materials science that leaves you feeling warm and fuzzy when you look at those sixteen flanges - but, sorry, I'm old with too Edisonian an outlook to view gear innovation through those same rose-colored glasses.

baja_java wrote:
i know what intuition you're basing that on, but that's if you're comparing a segmented lobe with all pieces made of aluminum versus a one-piece aluminum lobe the Link Cam design is different, which has a steel inner link, a steel middle link, and an aluminum outer link and in the connection between the steel and the aluminum segments, the connecting flanges are two outer steel ones and one thick aluminum one in the middle the obvious design flaw you're screaming and accusing everyone else to be in denial about seems like the kind of critical design issue that would be addressed early in the cam's development process one look at this segmented cam lobe, all i can tell you is that it's likely stronger than an all aluminum segmented design, and may well have the strength comparable to a one-piece aluminum lobe, and that a lot of thought has gone into its design.

A lot of thought has clearly gone into the design and manufacture of this product or we wouldn't be having this conversation. But no, none of my thoughts are in any way related to your steel vs. steel/alum vs. alum supposition. My perceptions would be exactly the same regardless of the materials. My concerns are entirely centered around the mechanical design and are based on the fact that no materials known today can deliver this four-flanged, segmented lobe design with the structural integrity of an unsegmented lobe cut from a solid block of aluminum. Sure, if forces remain close to an axis perpendicular to the axle, then yes, they will perform comparably - but, the minute those forces start to significantly diverge from the perpendicular, let alone just being applied laterally - all bets are off. That's because now we're talking about the ability of [multiple] linkage assemblies to resist deflection and deformation as opposed to that of a material.

baja_java wrote:
in a discussion like this, some people seem to think the more speculation there is, the better and some are way far on that extreme, who needs to not only shout out their speculation over everybody else's but also needs to demand its universal acceptance when everyone knows damn well it's just speculation it's almost psychotic. i'd rather keep the speculation minimal i personally don't think dirtme and i will be the only two ever with actual first-hand details of this kind of breakage. labs at Omega Pacific and Trango and others probably will too, at some point and with that, in time, much of the overzealous speculation would prove a total waste of time, as in unproductive

None of my comments in the two paragraphs above are overzealous or speculative - what is both blindly overzealous and dubiously speculative is the very idea these segmented cam lobe linkages possess anywhere near the strength of a solid block of material in the face of off-axis or lateral forces. It's exactly that unfounded illusion that is the root of my main concern of folks thinking they can just blindly slam these things in anywhere and expect them to automagically work.

baja_java wrote:
...some of you seem very adamant that the cause of failure has got to be one or the other, either the rotation and resulting leverage, or the force amplification i actually think it might well be both for example,

I've never limited the possible failure modalities to one or the other. Quite the contrary, I would in no way limit the potential failure modalities to those two - in reality, I don't think you can even begin to delineate all the potential failure modalities and circumstances. That's exactly why I keep harping on the idea that folks need to avoid placements with the potential to generate lateral loads on the cam lobe assemblies. To me that means restricting the use of these cams to reasonably clean placements.

baja_java wrote:
...so that if a cam rotates from side to side, like when the set of lobes on one side pulls out, the other set can pivot into another direction that might well have a significantly different flare profile that could be better or a lot worse, especially if the cam is jammed up against the back corner of that ellipsoid so i think it's possible that a rotation can further "amplify" a flare-induced force amplification.

Now I will speculate by saying I think any discussion or simulations of the performance of cams in flares is just that - highly speculative and very difficult to model. My principal concerns with Link Cams in flares is the tendency to load just one side of the linkages in in the segmented cam assemblies. Pivoting - for better or worse - is plain risky in that the links could break in the processes of rotating in addition to your concerns such rotation could add to the forces involved with a flare.

baja_java wrote:
...users of cams should really understand how cams work entrusting your life to a piece of gear the workings of which you don't fully understand, that's kind of crazy

Here we completely agree, but because this is clearly a prevailing attitude and approach is why I'm being so bulldog on this issue - accidents caused by innovative designs used blindly and without understanding will drive innovation out of the marketplace. Odd as it may seem, the best way to support continued innovation in climbing gear is to help folks understand the limitations of new designs so they can best make the most of the advantages they offer.

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