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healyje


Jan 5, 2008, 5:46 PM
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Re: [baja_java] Link Cam Report [In reply to]
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baja_java wrote:
[...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.

We certainly also agree on this point, however, the loose extended segments are also capable of 'snagging' on any placement obstructions in the event of cam rotation and so present some added risk that way.


Nnorthwall


Jan 5, 2008, 7:22 PM
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Re: [dingus] Link Cam Report [In reply to]
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My question is:
What type aluminum alloy use for broken middle Cams. If OP use casting aluminum alloy that is not enough strenghth to hold torsional force.
OP should analyse the casting aluminum alloy Cams.


healyje


Jan 5, 2008, 7:30 PM
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Re: [Nnorthwall] Link Cam Report [In reply to]
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http://www.omegapac.com/...oducts_linkcams.html

OP wrote:
The two, inner links on each lobe unit are built with a very new (and very expensive) process known as Metal-Injection- Molding which permits us to create detailed, precision pieces—like casting—with the strength of machined parts and are made from 17-4 aircraft stainless steel. The outer link is machined from 7000-series aluminum alloy.


mheyman


Jan 5, 2008, 7:37 PM
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Re: [baja_java] Link Cam Report [In reply to]
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I wanted to have better idea of multiplication of force due to different placement flair angles so I would have a better idea of exactly what it was I want to avoid. So here is a graph of the multiplication of force at angles from 0 to 27 degrees for a 14 degree cam angle.



I still don’t feel that these points have been made clear:

1) Cams will not pull in small angle flairs due to reduced friction. The angles will increase the outward (normal) force and more than compensate .

2) Increased outward forces will increase the chances of prying a blocks loose or breaking rock features.

3) Increased force due to placement flair is not linear and some place not to far above 20 degrees extremely high forces can be generated arresting a fall, and we should expect cams of any brand to break and placements to fail. I agree with JT that we already avoid these placements but for the wrong reason!

I have found this thread extremely informative. Like healyje and others some here I have avoided buying link cams solely because of the perceived weakness of their jointed cams and their complexity. I even made a statement that I would not buy cams that broke. But OP has responded that they designed the link, verified their expectation in tests and compare them to other cams on the market with favorable results. Unlike other mfgs mentioned, I trust OP. Read MDs response he’s a competitor!

At the same time I have learned of a failure mode that may well have caused the LC failure in this case which would have occurred to any other cam in the same type placement. If this was the case, then I will have to categorize this failure exactly like the biner comparisons that have been discussed. I think it would be helpful at this point for someone to estimate the possible flair angles the LST cam may have been placed at. I understand that there were other forces at play here and that it won’t be a definitive answer, but if it was likely that the placement flair exceeded 20 degrees then it should not be unexpected that the cam was broken.


(This post was edited by mheyman on Jan 5, 2008, 9:05 PM)
Attachments: graph.jpg (29.9 KB)


healyje


Jan 5, 2008, 8:02 PM
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Re: [mheyman] Link Cam Report [In reply to]
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mheyman wrote:
Like healyje and others some here I have avoided buying link cams solely because of the perceived weakness of their jointed cams and their complexity.

mheyman, would love to see that graph if you could take another shot at it. I do feel the need to clarify one thing, though. The reason I didn't purchase a Link Cam isn't because of the design limitations which I have been highlighting - I have no problem with those limitations. As maldaly pointed out, original friends had limitations but we worked with them. The reason I don't have any on my rack is because they're heavier than I care for and the particular benefit they offer - expanded range - just isn't compelling enough for me to bite. That and I'm totally o/c about my rack organization and don't want to make a change in it to [visually] accomodate it.

My other comment would be in regard to the ongoing conversation around performance of cams in flares. A lot of comments have been made to the effect that 'any make of cam would break'. Well, call me a naysayer yet again, but I think odds are way better that most conventional cams would simply pull and that the odds of these particular cams breaking is considerable higher.


jt512


Jan 5, 2008, 8:08 PM
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Re: [mheyman] Link Cam Report [In reply to]
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mheyman wrote:
I wanted to have better idea of multiplication of force due to different placement flair angles so I would have a better idea of exactly what it was I want to avoid. So here is a graph of the multiplication of force at angles from 0 to 27 degrees for a 14 degree cam angle.


If I understand this graph correctly, then I think I understand why we're not seeing cam failures due to force magnification in flared placements very often: there is no serious force magnification until the angle of the flare is very close to the maximum flare angle that the cam can be used. If I understand everything correctly, then, for a 14-degree cam, the maximum flare angle in your graph would be 28 degrees; beyond 28 degrees, the cam won't stick in the crack (per Kodas). But the all the serious force magnification takes place in the last degree; even in a 27-degree flare there appears to be only a 30 percent increase in the force.

Jay


Adk


Jan 5, 2008, 8:34 PM
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Re: [jt512] Link Cam Report [In reply to]
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I interpreted this graph the same way as Jay did. The graph helped to dumb it down for me. Being honest here... Though I did read the MIT link and fully comprehended it.
I have nothing to contribute but this, thanks for all this work going into this thread.


mheyman


Jan 5, 2008, 8:55 PM
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Re: [jt512] Link Cam Report [In reply to]
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jt512 wrote:
[img]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=1741;[/img]

If I understand this graph correctly...even in a 27-degree flare there appears to be only a 30 percent increase in the force.Jay

Sorry the graph show forces not force factor. (I'll relable).So the increase is
2x at a 14 degree flair.
4x at a 21 degree flair
8x at a 25 degree flair

Still your general idea is correct - I credited you and agreed in my post.


(This post was edited by mheyman on Jan 5, 2008, 9:03 PM)


Partner rgold


Jan 6, 2008, 11:28 AM
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Re: [mheyman] Link Cam Report [In reply to]
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A supplement to Mark's post: according to Vaino's analysis, the force F on the cam axle from cams on one side is

F = (1/2)csc(14-b)T,

or, if you if you don't like the cosecant,

F = T/(2sin(14-b)),

where T is the load on the cam stem, b is half the flare angle in degrees, and the cam angle is 14 degrees. (Vaino doesn't actually give this formula; it follows from his result for F by elementary trigonometry.)

The term (1/2)csc(14-b) thus represents a multiplier that converts the load to the cam stem T to the load to axle from the cams on one side. The one-sided axle loads are probably the ones that determine whether a cam will break near its attachment to the axle.

Some values (Flare angle here means 2b, the upper bound is 28 degrees):

Flare angle: 00.0 Axle load: 2T
Flare angle: 08.8 Axle load: 3T
Flare angle: 13.6 Axle load: 4T
Flare angle: 16.4 Axle load: 5T
Flare angle: 18.4 Axle load: 6T
Flare angle: 19.8 Axle load: 7T
Flare angle: 20.8 Axle load: 8T
Flare angle: 21.6 Axle load: 9T
Flare angle: 22.2 Axle load: 10T

Note that when Mark says, "2X at 14 degree flair," he means that the force on the axle is two times as great as it would have been for a parallel-sided placement, which corresponds to four times the stem load for a 13.6 degree flare shown in my compilation of values above.

One of the many things that makes this tricky is that the flare angle is a local property of the small region of contact between cam and rock. A crack that doesn't look particularly flared or only looks slightly flared might still have irregularities that would, from the cam's perspective, be much more flared. Most pockets do not have sides at a constant angle (they would appear conical if they did), they are more flared in back than they are near the front, so pushing a cam in deep will engage a highly flared section rather a less flared section nearer the outside.


Nnorthwall


Jan 6, 2008, 1:23 PM
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Re: [healyje] Link Cam Report [In reply to]
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what is the tensile strength(PSI) of the two inner link cams(metal injection molding parts)?

Suggestion: Metal injection molded two inner link cams should take X-ray picture for checking air pocket in the link cams.


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Jan 6, 2008, 4:54 PM
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Re: [rgold] Link Cam Report [In reply to]
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Thanks rgold, that makes things much clearer.

One question though, how would negative flare affect the equations. In other words a flare at a lesser angle than parrallel.


Partner baja_java


Jan 6, 2008, 5:11 PM
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Re: Link Cam Report [In reply to]
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mheyman wrote:
I think it would be helpful at this point for someone to estimate the possible flair angles the LST cam may have been placed at. I understand that there were other forces at play here and that it won’t be a definitive answer, but if it was likely that the placement flair exceeded 20 degrees then it should not be unexpected that the cam was broken.

i've already described it. that flared pod resembles one half of an ellipsoid. if you don't know what that is, you can take that flat oval opening shown in the photos and extend that shape deeper and deeper into the hole, with that flat oval getting smaller and flatter until that whole thing squeezes down into a rounded horizontal in the back. like an oval tubular hole that goes smaller and smaller until it comes to a rounded close in the back, and has tight curvature on the sides and along the back

the whole pod is flared, though not as bad on the floor and ceiling of the "pocket" area near the lip. but as you can see, as you move inward from the mouth toward the back, the flare angle steadily increases, starting at less than the cam angle and passing the cam angle and becoming greater than the cam angle near the rounded back. and worse, the same flaring also exists as you move from centerline out to either side, that the flare angle also goes from less than cam angle to greater than cam angle at either side wall. close to the back and close to the sides would be where the flair angle would change in range the most, as someone has pointed out:

rgold wrote:
Most pockets do not have sides at a constant angle (they would appear conical if they did), they are more flared in back than they are near the front, so pushing a cam in deep will engage a highly flared section rather a less flared section nearer the outside.

with all that curvature, plus irregularities, there are plenty of flair angles in there to choose from, including flair angles that are near the cam angle. just matter of hit or miss, unless one happens to be in what might feel like a "sweet" spot to place a cam


Partner rgold


Jan 6, 2008, 5:49 PM
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Re: [baja_java] Link Cam Report [In reply to]
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According to testing and modeling done by the Italian Alpine Club, a realistic if moderately serious leader fall (ff=0.7) results in a load to the top piece of about 6 kN, accounting for belayer motion and rope slippage. (This is a lower but more realistic number than you'll get from the standard equation and all of the internet fall calculators that are based on it.)

Medium to large cams are rated at 10 - 14 kN. I don't know what that rating means, surely it isn't a breakage threshold, but it is at least a suggestion that something, rock crumbling, shear yield, or breakage becomes more likely if that load is exceeded. Since parallel-sided placements produce double the stem load on the axle, this means that axle loads of of 20-28 kN are a consequence of the rating limits. Looking at the chart, flare angles on the order of 14 degrees, (these load the axle with 24 kN) will load medium to large cams up to or beyond those rated limits. For smaller cams rated at 8 kN, a 9 degree flair produces loads beyond the corresponding axle rating.

I'm not suggesting cams will break at these levels (I certainly hope not!), but this does illustrate how a moderate (local!) flair and a serious but far from catastrophic real-life fall can push cams past their published ratings.


Partner baja_java


Jan 6, 2008, 6:24 PM
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Re: Link Cam Report [In reply to]
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healyje wrote:
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.

hello? that's what those cited test results showed, that the Link Cam is comparable to other cams in that latter regard. the results by Omega Pacific and Trango are limited. but that's limited evidence versus your ZERO evidence. do you have any data that support your claim that their design has got to be flawed? have you broken that cam yet? what have you learned? instead of raving about group-think and blinding consumerism and suburban life, maybe you should work on that instead

healyje wrote:
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.

only to people with speculative angst who can't come to grips with the fact that sometimes these things take a little time (likely not much time at all in this case), to people like you who think they're entitled to everything right here and right now, so you can feed off of every bits and pieces of the latest and churn out more speculations founded or unfounded. of the tens of thousands who use this site everyday and the hundreds or more who have followed this discussion, you're the only one throwing a pissy fit over this

not overzealous? you accused everyone else who don't agree with you that they're in denial. you went against limited evidence based on your zero evidence and claim the linkages simply "have got to be" weak and thereby imply the people at that gear company are the kind who would let a design error of this magnitude make it out onto market

we're not refraining from blaming the equipment right away like you're doing because we're oh so taken by the fancy technology, as you so casually generalized. and no, we're not relying on faith alone like you want to think either. you are wrong. again, there are the cited test results. the data are limited, but not completely meaningless. that versus your zero evidence. furthermore, unlike your blind belief alone on what "ought" to be, i'm also capable of evaluating the kind of major design flaw you're suggesting and how that should bear out in field use by myself and others. Link Cams are not yet as popular and owned worldwide like some other cams are. but enough people out there do have and use them. if what you claim were true, that the joints are as flimsy as you say, at many many places you'd run into people with horror stories about how theirs have just shattered left and right. but that's not the case. more likely those people would tell you how great their range is, how they've become their "go to" pieces, or wish how they could be even lighter, or some who might say how theirs walked and got "stuck" and ended up somebody else's booty. aside from the Inspection Notice that seems to have passed, no, nothing about breakage, until this incident with a flared pod

do you understand what happens to cams in flared placements, Joseph? understand. not recite a few formula or the conclusion at the end of Vaino's formulation. not regurgitate a catch phrase or two that others have used. i'm asking because it seems if you did understand, you should at least consider that as a possible cause that should not be discounted, and be less fanatical in unilaterally declaring (with no test data of your own or from anyone else) that the linkages on the cams has got to be a design flaw. see, others and i do understand. we can therefore see a completely plausible scenario where this cam or any other cam could be broken. i'm aware that the equipment might be at fault too, by design. that is possible, though seems unlikely, after limited test results were cited and if one would simply apply a little reasoning. and i'd rather not immediately blame the equipment without at least trying to eliminate the former possibility. unlike you, i just don't believe in ignoring a possible explanation and go straight for the equipment angle and start insinuating a fault in a design that might well not be faulty, and in effect bad mouth a company that might well have not done anything wrong, who doesn't really deserve this. so again, do you really comprehend the principles described in Vaino's link or elsewhere? do you really grasp what that's about?

i can tell that you don't give a rat's ass about how what you say regarding a gear design and your unfounded speculation and claim might affect a gear company who might well have done nothing wrong. but i'm not like you. here, the caution has already been raised by the first incident. there's no real urgency for disclosure for my case. not that i haven't already given everyone a headsup, and stating clearly that more is likely forthcoming soon. i know this isn't important to you, but there is an effect on a gear company here that is significant enough to warrant consideration, and i believe it's the right thing to do in this instance to extend that consideration. all i'm doing is giving them the opportunity to see what i did to my fractured cam and see if our thinkings are along the same lines, about whether this second incident is exactly the same or nowhere near the same as what happened before. i need to talk to them about that in order to do that, when they've got the cam in hand. and they will likely need to talk to me too, as they've already said. it's like when you set up an experiment to test something, even after you've gotten the results, you still have to go back and make sure you've created the conditions correctly. others like rgold, curt, dingus, jay, k.l.k, murf, mheyman, etc, they don't seem to have a problem with this. the only one who is making this obnoxious demand is you, because you just can't come to grips that for now the basic info i've given does suffice, that me having said more is likely to come soon should suffice, that in a few days there may well be all the info anyone would want, that you seem to think your need to know everything right now should overrule everything else. well, if you still don't get it, let me tell you loud and clear. with respect to what's going on, you're just not that important, Joseph. it's nothing personal. it's just what i think is the responsible way to handle this

this discussion started by longdraw (and dirtme) is an accident report. mine is not an accident report. if it were, climber and eyewitnesses like dirtme and longdraw would usually be the best ones anyway to present what happened. and there wouldn't be any need for them to first go back and make sure that they've created the "accident conditions" correctly according to spec's on the day they've decided to be at the same place and the same time to have and to witness said accident. if you didn't realize before, i hope you will realize by now that, really, you just need to calm down

you know, it's not like i've decided to hide the fractured cam in the basement and keep its fractured coolness all to myself and have decided not to let anyone else see it ever. after the fracture, i immediately contacted Omega Pacific and express mailed it to their place in WA. i sent it ASAP to the one place that needs to have it the most, and there's now an evaluation process that goes with that that might well be quite short. sorry if Joseph on some forum discussion on the internet has to take a backseat. yeah, quite the tragedy

you should take a timeout and reconsider a little about your own behavior thus far, before crusading to alter the generalized attitudes of others who climb


Partner rgold


Jan 6, 2008, 8:17 PM
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Re: [philbox] Link Cam Report [In reply to]
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philbox wrote:
One question though, how would negative flare affect the equations. In other words a flare at a lesser angle than parrallel.

A quick check of the geometry shows that the same equation gives results for negative flare values. As Vaino set it up, the half flare angle b for the left crack wall is a clockwise rotation from the 6 o'clock position. A negative flare angle for the left crack wall has half flare angle b a counterclockwise rotation from 6 o'clock.

Negative flare angles correspond to crack walls that we would say constricted as you move down, rather than flaring outward (negative flares often call for nuts). The axle loads for negative flares decrease from 2T, but not very fast. As the flare angle approaches -180 degrees (crack walls become a horizontal surface) the axle load approaches T. (Achieving these values assumes the cams could be sufficiently retracted).

When I get it uploaded, a basic graph that extends Mark's graph will appear below. Think of the negative angles on the flare axis as measuring the angle of constriction of the walls.




(This post was edited by rgold on Jan 6, 2008, 8:31 PM)


mheyman


Jan 6, 2008, 8:22 PM
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Re: [rgold] Link Cam Report [In reply to]
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I don’t have time to write more, so I’ll just say I think that RG’s polite way of saying there was an error in my math. Not sure where cause I thought I just followed Vainos Eq. Guess I won’t get partial credit since I din’t show my work! To any else, just use RG’s numbers, undoubtebly his are correct, and I am quite happy to be corrected by him.

RG – I haven’t used a half angle conversion since the little grad school I did – though I obviously still recognize them.

Baha_Java I know you described them – but I can’t tell anything from the photos – we need likely angles to say look, no wonder it broke.


Partner rgold


Jan 6, 2008, 8:35 PM
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Re: [mheyman] Link Cam Report [In reply to]
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Mark, I don't think there is anything the matter with your numbers. I thought it might be valuable to give the simple equation (since Vaino doesn't do that), compute some more values, and try to clarify what the numbers measure.


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Jan 6, 2008, 9:10 PM
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Re: [healyje] Link Cam Report [In reply to]
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healyje wrote:
baja_java wrote:
[...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.

We certainly also agree on this point, however, the loose extended segments are also capable of 'snagging' on any placement obstructions in the event of cam rotation and so present some added risk that way.

I've been thinking about LCs rotating into different orientations lately. The inner lobes (assuming the outer lobes are the contacting rotation points) will slide sideways, with the smallest lobes traveling through the largest arc. This is a significant difference between traditional cam designs and the new multi-lobed units which introduces new failure modalities.


healyje


Jan 6, 2008, 11:20 PM
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Re: [baja_java] Link Cam Report [In reply to]
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baja_java wrote:
healyje wrote:
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.

hello? that's what those cited test results showed, that the Link Cam is comparable to other cams in that latter regard. the results by Omega Pacific and Trango are limited. but that's limited evidence versus your ZERO evidence. do you have any data that support your claim that their design has got to be flawed? have you broken that cam yet? what have you learned? instead of raving about group-think and blinding consumerism and suburban life, maybe you should work on that instead

The tests that have been presented by vendors have been clinical engineering tests - not particularly representative of the real world, especially places like JT. Again, you folks who obsess over "data" are actually pretty funny from my perspective given you'd need a few more petaflops than are currently available to do a decent model of that JT pod. And my god - just how did anyone climb without data? Hey, as I said, measure the thickness of one of the middle segment flanges - if you need more data than that you really are living in a wonderland where everything is perfect until proven otherwise. Bill and I are coordinating on getting together to break the cam and at the moment are scheduled to do it tomorrow night. We'll post up our "data" once we're done.

But again I need to be explicity clear - I in no way find the design of the Link Cam "flawed", as you state above, any more than I find the design of the original Friend flawed because it had a rigid stem. What I am saying is the design has limitations.

baja_java wrote:
only to people with speculative angst who can't come to grips with the fact that sometimes these things take a little time (likely not much time at all in this case), to people like you who think they're entitled to everything right here and right now, so you can feed off of every bits and pieces of the latest and churn out more speculations founded or unfounded. of the tens of thousands who use this site everyday and the hundreds or more who have followed this discussion, you're the only one throwing a pissy fit over this

Actually, that's a pretty angst-ridden paragraph as they go. Maybe you'd care to explain how 'these things' can 'take a little time'? The facts of an event require no more time than the event itself - a technical analysis of those facts may take 'a little time', but the facts of an event do not. Again, I am totally in support of the use of these cams regardless of your cam or the breakage of JT. My 'speculation' is based on over three decades of climbing and breaking a lot of shit.

baja_java wrote:
not overzealous? you accused everyone else who don't agree with you that they're in denial. you went against limited evidence based on your zero evidence and claim the linkages simply "have got to be" weak and thereby imply the people at that gear company are the kind who would let a design error of this magnitude make it out onto market

As said above, that a tri-segmented cam lobe design might likely be weak is in no way a "design error", it is simply an unavoidable consequence of the fact that materials science at the start of the 21st century unfortunately can't yet deliver indestructable materials for our entertainment. I'd personally love incredibly light and virtually unbreakable spider silk ropes and indestructable cams, but they don't exist. In the meantime I and everyone else needs to be sure and work within the design constraints of our gear.

baja_java wrote:
we're not refraining from blaming the equipment right away like you're doing because we're oh so taken by the fancy technology, as you so casually generalized. and no, we're not relying on faith alone like you want to think either. you are wrong. again, there are the cited test results. the data are limited, but not completely meaningless. that versus your zero evidence. furthermore, unlike your blind belief alone on what "ought" to be, i'm also capable of evaluating the kind of major design flaw you're suggesting and how that should bear out in field use by myself and others. Link Cams are not yet as popular and owned worldwide like some other cams are. but enough people out there do have and use them. if what you claim were true, that the joints are as flimsy as you say, at many many places you'd run into people with horror stories about how theirs have just shattered left and right. but that's not the case. more likely those people would tell you how great their range is, how they've become their "go to" pieces, or wish how they could be even lighter, or some who might say how theirs walked and got "stuck" and ended up somebody else's booty. aside from the Inspection Notice that seems to have passed, no, nothing about breakage, until this incident with a flared pod

You need to go back and read my posts considerably more carefully - OP couldn't find a bigger supporter in all this discussion than me. I'm in fact trying to insure designs as innovative as the Link Cam continued to be offered by gear manufacturers. But they won't continue to be offered if people are incapable of using the within the scope of their [design] limitations. Using them while simultaneously denying such limitations exist is the problem, not the cams. These cams are new to the market and before they were ever on the shelves of retiailers I did predict we'd be having this conversation sooner than later and that's what's happening. And we'll be seeing more of these cams come apart over time - and in the vast majority of cases it will be pilot error just like the one which started this discussion.

baja_java wrote:
do you understand what happens to cams in flared placements, Joseph? understand. not recite a few formula or the conclusion at the end of Vaino's formulation. not regurgitate a catch phrase or two that others have used. i'm asking because it seems if you did understand, you should at least consider that as a possible cause that should not be discounted, and be less fanatical in unilaterally declaring (with no test data of your own or from anyone else) that the linkages on the cams has got to be a design flaw. see, others and i do understand. we can therefore see a completely plausible scenario where this cam or any other cam could be broken. i'm aware that the equipment might be at fault too, by design. that is possible, though seems unlikely, after limited test results were cited and if one would simply apply a little reasoning. and i'd rather not immediately blame the equipment without at least trying to eliminate the former possibility. unlike you, i just don't believe in ignoring a possible explanation and go straight for the equipment angle and start insinuating a fault in a design that might well not be faulty, and in effect bad mouth a company that might well have not done anything wrong, who doesn't really deserve this. so again, do you really comprehend the principles described in Vaino's link or elsewhere? do you really grasp what that's about?

I understand just fine, and don't need the math to explain the graph or rgolds description of the phenomena. I also don't need the math after thirty three years of climbing to know most convential cams will blow out of flares rather than break. One will on rare occasion - but the vast, overwhelming majority blow, not break. So, if it's your belief, based on your understanding of the math, that any cam would break in the same circumstances where I consider the Link Cams to be more vunerable, then I would say the "data" doesn't support your thinking or we'd be seeing conventional cams break in flares 'left and right' as you say. They plainly do not.

baja_java wrote:
i can tell that you don't give a rat's ass about how what you say regarding a gear design and your unfounded speculation and claim might affect a gear company who might well have done nothing wrong. but i'm not like you. here, the caution has already been raised by the first incident. there's no real urgency for disclosure for my case. not that i haven't already given everyone a headsup, and stating clearly that more is likely forthcoming soon. i know this isn't important to you, but there is an effect on a gear company here that is significant enough to warrant consideration, and i believe it's the right thing to do in this instance to extend that consideration. all i'm doing is giving them the opportunity to see what i did to my fractured cam and see if our thinkings are along the same lines, about whether this second incident is exactly the same or nowhere near the same as what happened before. i need to talk to them about that in order to do that, when they've got the cam in hand. and they will likely need to talk to me too, as they've already said. it's like when you set up an experiment to test something, even after you've gotten the results, you still have to go back and make sure you've created the conditions correctly. others like rgold, curt, dingus, jay, k.l.k, murf, mheyman, etc, they don't seem to have a problem with this. the only one who is making this obnoxious demand is you, because you just can't come to grips that for now the basic info i've given does suffice, that me having said more is likely to come soon should suffice, that in a few days there may well be all the info anyone would want, that you seem to think your need to know everything right now should overrule everything else. well, if you still don't get it, let me tell you loud and clear. with respect to what's going on, you're just not that important, Joseph. it's nothing personal. it's just what i think is the responsible way to handle this

I never said I was important. What I am saying is that information about gear failures should be completely open and transparent and there is no reason of merit why they should not be.

baja_java wrote:
this discussion started by longdraw (and dirtme) is an accident report. mine is not an accident report. if it were, climber and eyewitnesses like dirtme and longdraw would usually be the best ones anyway to present what happened. and there wouldn't be any need for them to first go back and make sure that they've created the "accident conditions" correctly according to spec's on the day they've decided to be at the same place and the same time to have and to witness said accident. if you didn't realize before, i hope you will realize by now that, really, you just need to calm down

I'm exceedingly calm, but to repeat, there is no reason of merit why you can't simply say how you broke the cam. I'm guessing you could have easily done it by now in a tenth of the words you've managed in this post.

baja_java wrote:
you know, it's not like i've decided to hide the fractured cam in the basement and keep its fractured coolness all to myself and have decided not to let anyone else see it ever. after the fracture, i immediately contacted Omega Pacific and express mailed it to their place in WA. i sent it ASAP to the one place that needs to have it the most, and there's now an evaluation process that goes with that that might well be quite short. sorry if Joseph on some forum discussion on the internet has to take a backseat. yeah, quite the tragedy

The only one who is importing the necessity for secrecy and silence is you. OP has no such requirement - shit breaks, get used to it - trust me, they and every other reputable gear manufacturer are.

baja_java wrote:
you should take a timeout and reconsider a little about your own behavior thus far, before crusading to alter the generalized attitudes of others who climb

The 'generalized attitudes of others' on display in this thread and a lot of others are largely of two extremes - one an unyielding belief that gear should and does work automagically and indestructably, and the other which goes into a blind hysteria when a piece of gear breaks. I have little doubt of the cause of this marked deterioration of personal responsibility and inability to simply accept the reality of gear as it hangs on their racks, but that would be another thread entirely.


(This post was edited by healyje on Jan 7, 2008, 1:27 AM)


Partner cracklover


Jan 7, 2008, 7:17 AM
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Re: [dominic7] Link Cam Report [In reply to]
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dominic7 wrote:
healyje wrote:
baja_java wrote:
[...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.

We certainly also agree on this point, however, the loose extended segments are also capable of 'snagging' on any placement obstructions in the event of cam rotation and so present some added risk that way.

I've been thinking about LCs rotating into different orientations lately. The inner lobes (assuming the outer lobes are the contacting rotation points) will slide sideways, with the smallest lobes traveling through the largest arc. This is a significant difference between traditional cam designs and the new multi-lobed units which introduces new failure modalities.

Could you explain what you mean? I'm not getting your drift at all.

Thanks,

GO


dingus


Jan 7, 2008, 7:49 AM
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rgold wrote:
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?

Hmmm, I think it is nearly impossible to prevent the retracted lobes from contacting irregularities side a crack.

If we take the cautionaries to heart.... then the link cam should only be placed in perfectly parallel, smooth sided cracks where the stem is in perfect line with the directon of force.

If that's all link cams are good for then I'm afriad they lose a lot of utility.

Cheers
DMT


Partner rgold


Jan 7, 2008, 9:05 AM
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If that's all link cams are good for then I'm afriad they lose a lot of utility.

Dingus, I'm concerned that the comment of mine you referred to is, first of all, too speculative, and second of all, not clearly written. I don't own a link cam and don't know exactly how they work, as I hope I have made clear---so my opinions are clearly tainted.

I was looking at a photograph of the placement that appeared to have contact on one wall with the lower red cams and on the other wall with a cam from one of the two smaller segments. What you can't tell is whether the smaller cam contacting one wall has its twin segments contacting the other wall. If this is NOT the case, then you'd have what I was calling an asymmetrical placement with the load on one wall applied by cams from a different segment from the load on the other wall. I don't know if this is even possible, i.e. if the cam will stay in place in such a situation.

If it is possible, this is different than your concern, namely that perhaps bigger cams might ALSO touch in a placement involving smaller segments that are symmetrically in contact with the crack. What I'm saying is that a link cam is really a combination of three sub-cams, and in any particular placement, at least one of those three sub-cams, thought of individually without regard to the other two, ought to be actually placed.

Am I getting murkier?


giza


Jan 7, 2008, 9:55 AM
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dingus wrote:
If we take the cautionaries to heart.... then the link cam should only be placed in perfectly parallel, smooth sided cracks where the stem is in perfect line with the directon of force.

If that's all link cams are good for then I'm afriad they lose a lot of utility.

Cheers
DMT

Ditto - said it before and I'll say it again, innovative design but no place on my rack for a piece of gear with such functional limitations. I've returned three of these cams to OP and now have another new red and repaired yellow in my closet... they should probably stay there.


wmfork


Jan 7, 2008, 11:42 AM
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giza wrote:
Ditto - said it before and I'll say it again, innovative design but no place on my rack for a piece of gear with such functional limitations. I've returned three of these cams to OP and now have another new red and repaired yellow in my closet... they should probably stay there.

or sell them to dudes that primarily climb at the creek...


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Jan 7, 2008, 12:09 PM
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ok, Joseph, tell me this first. do you think the failure of the OP's cam on Left Ski Track happened within the design spec's, or beyond the design spec's? you think the rotation into blockage causing torque leading to a part snapping is what happened, i believe (correct me if that's not the case)

don't worry, i'll get to the rest of that mess you replied with. there are some very basic ideas that you just don't get, and i'll go over them with you. but first, answer the above question

In reply to:
I understand just fine, and don't need the math to explain the graph or rgolds description of the phenomena. I also don't need the math after thirty three years of climbing to know most convential cams will blow out of flares rather than break. One will on rare occasion - but the vast, overwhelming majority blow, not break.

by the way, if you went ahead and skipped the math, that means you've never proven to yourself that what Vaino described is true. you merely took his words for it and keep regurgitating what he said you're supposed to think. that's vastly different than truly understanding something. you've made it apparent that you've never encountered the phenomenon he described out in nature on your own, so that removes the possibility that you could've understood that from direct experience. one can glean an understanding from Vaino's formulation if they aren't allergic to math like you are, who can't understand what the math conveys. that's important because the how's and the why's are in the math. why do you think Vaino went through the trouble of including them, if he could've just summarized his gist in a few paragraphs? math is just a language. like English or Italian. i understand it fine. that's why i'm not afraid of math like you are, and often stumped by math like you are. nor does that means i'm obsessed by it either. there isn't some compulsion to see the world in numbers and data like you hope as the typical stereotype suggests. you're so afraid of this incomprehensible language that you need to convince yourself that other people who use it must use it to an obsessive degree, that they must be abnormal, because at least that would mean your lack of ability in using it would at least seem somewhat normal. here's another thing. for my pay grade, to borrow someone's phrase from earlier, i'm embarrassingly inept at computers and all this fancy technology you seem to think others like me should be hopelessly dependent on. i know enough to do what i need to do, that's all, and that's ok with me. yes, there are people who "obssesses" more about it, but to me, computers are just a tool. same with cams or nuts. the person still do the thinking that would apply the tools. so please, give it a rest with your incessant attempts to paint other people as techno drones like that's some deficiency that keeps them from relating to your beautiful great world views

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