What is a 'fair' placement??? On the scale 'poor' - 'fair' - 'good', I would expect 50% of cams to blow out of fair placements so you have proved nothing to me.

interesting, but its what I have suspected all along. Navy doesn't know what he's doing. This tells us more about Navy's shitty cam placement than anything else. Fuck dude the cam was basically at your feet and it ripped? Stick to top roping.
I've heard of at least a few different brads of cams blowing apart from shitty placements. its a dangerous game.
so you have a defective cam or your placement sucked.

Thanks USNavy some very thought provoking work. It would have been fantastic if you had taken photographs of the 'fair' placement in each case. As i currently stands this asks as many questions as in answers.

I suspect that the OP link cam was placed in a situation where the unused portion of the cam was extended and touching the rock. When the cam was loaded, this loaded the cam arm and torqued the axle. I doubt the axle was bent by normal cam contact forces.

There already has been one case on this forum of link cams breaking from this fashion.

(I say this because I have faith in OP design and quality control, the can should be fine in conventional placements.)

don't you have a pull tester?

i vote pull test to see what happens

You are making some pretty large sweeping judgements about cams and companies when you have left so so many variables in place.

It has already been made clear that the link cam is a specialty piece that requires more care and thought when placing. The fact that you didn't even mention the known limitations of the link cam, and the fact that you didn't mention that you took these limitations into account suggests to me that you, in fact, didn't take them into account.

Until you redo the "test" with pictures of placements its meaningless. Until you can do a better job of explaining what in your opinion is a "fair" placement this "test" is useless.

For somebody who shows a pretty good head for science and lab procedures you have left some huge holes in place. Especially given the pretty damning tone of your post. Not fair. Not fair at all.

a couple of thoughts.


all else aside, this does show that placements- fair or not, can fail and folks who are new to the game need to understand that. spending time following an experienced leader and also time spent on ground school and, ideally, on a few pitches of aid, can go a long way toward teaching new folks what a good/fair/marginal/bad placement looks/feels like before they find themselves 50' up and wondering if the gear underneath them will hold a fall.

Wow, it seems a fair number of folks on here missed the point.
The f*ing axle seems to have warped slightly due to the fall.
Can you take a top-down picture as well? Like, of the link cam so we can see it more clearly?

Wow, it seems a fair number of folks on here missed the point.
The f*ing axle seems to have warped slightly due to the fall.
Can you take a top-down picture as well? Like, of the link cam so we can see it more clearly?

Hey, Navy ...

If you'd like us to take a look at that cam, call us for a Return Authorization and we'll inspect it for damage.

The lobes look a little tweaked, but it doesn't mean the axle's bent. The inspection will reveal if it is, but my bet is that it's not.

The inner-most links (the ones attached to the axle) require a lot more rotation than any other cam on the market. As such, they require a little more tolerance between the inside diameter of the link and the outside diameter of the axle. Because of that relationship and that the springs apply some side force to the lobe assemblies, sometimes, they can sit slightly askew on the axle. I'm guessing that's what we're seeing in your photos.

Why'd the Link Cam pop when the Camalot didn't? I wish I could tell you. There isn't a lot of information or photos included about the type of placement, so it's impossible for me to speculate. However, we've found through exhaustive testing, as others here have mentioned, that minor variables can significantly effect the holding power of one cam over the other ... or even the same cam from one placement to another in the same feature.

But if you'd like us to give your cam a checkup, we'd be happy to.

--ML

___________________
Michael Lane
Omega Pacific
800.360.3990

Actually, the axle looks straight to me. Yes, the lobes are off a little, but the axle itself looks fine (take a pen, hold it up to the photos).

If you take a larger BD cam (I only say BD because they are the only larger cams that I have) you can see an amazing amount of play in the lobes. Not having used link cams, I'm not sure how much play their lobes have, but it's something to consider.

Yup my c4 #3's and 4's lobes look a bit skewed, but still rock solid. It looks like the axel is warped, but its just an optical illusion ooooouuuuuu.

Girl:"Wow! It's a schooner!"
Willam:"You dumb bastard! That's not a schooner, it's a sailboat!"

... Your logic is flawed. You can't make sweeping assumptions based on a single data point that isn't statistically significant...

Personally I think some people here are being a little harsh on USNavy personally. He put the time, money and effort into doing this test and then he posted it online for us to see.

Like others I don't think much can be concluded from the results. The tests don't really say much and the OP cam may not even be broken.

Anyway I thank USNavy for providing us with this information despite me thoughts on its usefulness.

Also Michael Lane handled this quite well. Nobody likes to see their company's cam rubbished. ML seems to have restrained his comments well. Plenty of others have stepped up to defend OP.

Personally I think some people here are being a little harsh on USNavy personally. He put the time, money and effort into doing this test and then he posted it online for us to see.

Like others I don't think much can be concluded from the results. The tests don't really say much and the OP cam may not even be broken.

Anyway I thank USNavy for providing us with this information despite me thoughts on its usefulness.

Also Michael Lane handled this quite well. Nobody likes to see their company's cam rubbished. ML seems to have restrained his comments well. Plenty of others have stepped up to defend OP.

The Link cam could have blown away bad rock, or it could have been in a bit of a pod which the Link cam didn't sit in quite as well. Heck, he didn't end tell us what type of rock he placed it in!

Hey USnavy-

Mind fixing the thread title? You have it as "OP Max Cam" rather than "OP Link Cam".

The lobes come like that new. I shopped several places before buying my .5 OP because I thought something was wrong and they were all identical.

fourth- you mentioned that the BD slipped an 'inverted sideways'- does this mean that the stem was not oriented downward for these placements?

Can you take a top-down picture as well? Like, of the link cam so we can see it more clearly?

Does the cam retract and spring back properly? Is there extra play in the cams? Oh right, you didn't take pictures of the cams before the 'experiment'. One of the main principals in a scientific report is reproducibility.

A photo of the 'fair' placement would have greatly added to your credibility. As it stands there is anecdotal evidence of possible damage due to a fall on a cam in an unknown placement. You do realize that climbers are incredibly superstitious and get rather hysterical over their gear...

I find it suspicious that the metal on the OP is chewed up, as if it really took a harder fall.

8kN is the min rating (Strength 8 - 14 kilonewtons) on the Link Cam in .5 size.

Is it not possible that you may have easily hit that number without knowing it?

It sure sounds, though, like the direction of the fall line was not the same as the orientation of the cam. In such a situation, a fall of factor .3 is *not* a minor fall, as far as the the impact on the cam is concerned.

It sounds like the BD cam had two of its lobes ripped out of the placement, such that the final position in which it caught the fall was more in line with the fall line.

Your logic is flawed. You can't make sweeping assumptions based on a single data point that isn't statistically significant, especially with so many variables and factors and imperfections applying strange forces in an outdoor crack real world scenario.

One of the main principals in a scientific report is reproducibility

However, the flaming by those who never present data was, as too often the case, intemperate and vacuous.

[T]he flaming by those who never present data was, as too often the case, intemperate and vacuous.

The stem was pointed downwards in anticipation of the fall pull direction in both cases. When I placed the C4 .4 all four lobes were orientated downwards. When I got back up, I noticed the inner two lobes slipped some allowing the C4 to rotate counterclockwise approximately 45 degrees.

A similar thing happened with the OP cam that I did not list. Two of the lobes on the OP cam have two separate bite marks in two separate locations. It appears that when the OP cam pulled, it expanded and grabbed into a second placement on two lobes, then slipped again. You can see two separate set of bite marks below.

His "data" is damn-near meaningless and he's trying to use it to paint a doom-and-gloom picture of Link Cams. It's unfair to OP and insulting to the intelligence of the RC.com reader, whether that reader "presents data" or not.

And yet, although incomplete, it is more information than you had yesterday.....

Thanks for starting down the road Navy.

This is fuckin bullshit, if the Knob is going to post this stuff then it's just Jackass for n00bs, and this thread has zero empirical content.

btw- the pictures from the top definitely show major deformation of the axle...definitely send the cam back to OP.

Don't think this is the case. Ignore the springs and just look at the nuts at the end of the axle and the part in the center where the cable attaches. They appear to be straight. The springs create the illusion of a bent axle because they are not parallel to the axle.

If it was bent, it would be bent in the opposite direction of the way it appears to be bent. The outer lobes would have more torque on the axle and it would bend so that the outer lobes spread and the inner lobes come together. Go look at the camalot pull test thread to see what I mean.

In pic #2 above, there are scrapes on the outside, non-contact face of the cam. How did that get there? That should not have happened in a normal placement or fall.

I just flipped a coin and it came up heads. You now have even more information than you had yesterday.

Curt

Kerwin, that is a very elitist attitude. This is America. This is a democracy. Anybody can make climbing equipment, anybody can test climbing equipment, and so can anybody else. You, on the other hand, seem to be implying that it would be preferable for such tasks to actually be undertaken by individuals possessing relevant knowledge, training, and skill. You should be praising USNavy for the effort he has put into contributing to the climbing community, not castigating him for no other reason than his results were meaningless. Haven't you ever heard of giving an A for effort?

Jay

I just flipped a coin and it came up heads. You now have even more information than you had yesterday.

Curt

Kerwin, that is a very elitist attitude. This is America. This is a democracy. Anybody can make climbing equipment, anybody can test climbing equipment, and so can anybody else. You, on the other hand, seem to be implying that it would be preferable for such tasks to actually be undertaken by individuals possessing relevant knowledge, training, and skill. You should be praising USNavy for the effort he has put into contributing to the climbing community, not castigating him for no other reason than his results were meaningless. Haven't you ever heard of giving an A for effort?

Jay

The only thing I would admonish USN for is his presentation of the information as a factual test, rather than a "hey this cam failed, and this one didn't in this specific placement".

Thats not something that could happen from that minor of a fall, especially when the piece pulls.

It’s impossible for the Link Cam to have held a higher impact force because the cam did not yield to the full force of the fall like the C4 did

The cams were orientated in the direction of the anticipated fall. Falling from a distance where my feet was only slightly over the cam with about 25 feet of rope out is a minor fall.

Kerwin, that is a very elitist attitude. This is America. This is a democracy. Anybody can make climbing equipment, anybody can test climbing equipment, and so can anybody else. You, on the other hand, seem to be implying that it would be preferable for such tasks to actually be undertaken by individuals possessing relevant knowledge, training, and skill. You should be praising USNavy for the effort he has put into contributing to the climbing community, not castigating him for no other reason than his results were meaningless. Haven't you ever heard of giving an A for effort?

Jay

Kerwin, that is a very elitist attitude. This is America. This is a democracy. Anybody can make climbing equipment, anybody can test climbing equipment, and so can anybody else. You, on the other hand, seem to be implying that it would be preferable for such tasks to actually be undertaken by individuals possessing relevant knowledge, training, and skill. You should be praising USNavy for the effort he has put into contributing to the climbing community, not castigating him for no other reason than his results were meaningless. Haven't you ever heard of giving an A for effort?

Jay

Actually, I believe that this test *does* show something, but not what the tester supposes.

What we can learn from the test is that, based on a sample size of 2, the probability of a cam failing in a poorly characterized "marginal placement" in response to an unmeasured impact force is 0.500 ± 0.487¹; that is, roughly speaking, somewhere between 0 and 1.

Before the test, most competent climbers knew not to trust marginal placements; however, based on these results, I don't think we can make such a blanket statement anymore—the confidence interval is just too wide. It seems that the test may actually have subtracted from our body of knowledge.

Jay

_____________
¹Mean ± 95% confidence interval.

Again, if the cam was torqued due to something you did not anticipate about either the placement or the fall (you state that the cams were placed in line with the anticipated force, but also that the BD cam rotated 45 degrees) then that 6.5kN force in the direction of pull could result in very high forces at the individual lobes.

GO

What do you mean by "torqued"?

What we can learn from the test is that, based on a sample size of 2, the probability of a cam failing in a poorly characterized "marginal placement" in response to an unmeasured impact force is 0.500 ± 0.487¹; that is, roughly speaking, somewhere between 0 and 1.

Before the test, most competent climbers knew not to trust marginal placements; however, based on these results, I don't think we can make such a blanket statement anymore—the confidence interval is just too wide. It seems that the test may actually have subtracted from our body of knowledge.

Jay

_____________
¹Mean ± 95% confidence interval.

What we can learn from the test is that, based on a sample size of 2, the probability of a cam failing in a poorly characterized "marginal placement" in response to an unmeasured impact force is 0.500 ± 0.487¹; that is, roughly speaking, somewhere between 0 and 1.

Before the test, most competent climbers knew not to trust marginal placements; however, based on these results, I don't think we can make such a blanket statement anymore—the confidence interval is just too wide. It seems that the test may actually have subtracted from our body of knowledge.

Jay

_____________
¹Mean ± 95% confidence interval.

It was pulled in such a way as to produce rotation or torsion on the piece.

Haven't you ever heard of giving an A for effort?

Jay

Sorry, as the a newbie I shouldn't throw stones at the glass house, but really....


Is this like the trophy for participation that the non winning team gets, or school award for good attendance?

Effort gets you the privileged of participating, A's are only for those who both try and succeed above and beyond, I've been constantly told.

USNavy's efforts mean that he now gets to be a subject for discussion, and allowed to participate - but doesn't make what he has to say any more or less valid...the results must speak for themselves. In this case? That would be for all you experts to decide.

On the newbie perspective.. learning interesting stuff about cams...and the viability of a conclusion made off a single data point...,I love seeing science determine what it "good." I learn lots...

cheers

ls

Are you saying that reading this made us dumber, according to the statistics?

I would sure as hell like my brain cells back.

Curt

It was pulled in such a way as to produce rotation or torsion on the piece.

GO

I would sure as hell like my brain cells back.

Curt

Ha! But no, I'm serious.

Maybe these pictures will help alittle well we are waiting on the placement pictures.

This is the route I placed the cam on. The red arrow indicated the approximate location where I tested the cam. If I remember right the actual location of the cam is just slightly below the end of the picture.

Yeah, what is with the bolts? You can see two of them in the bottom picture. Does this indicate unreliable rock so that apparently solid placements would simply blow out? I hope so, as it would answer both why your placement failed and why such an easily protected route is bolted. Also, though one can not really tell, it looks as if that crack is very non-uniform, lending itself to passive gear and also increasing the possibility that the link cam was torqued in the fall. In other words- many previous posters appear to have the correct diagnosis.

K.l.K has a very good point if US was not backed up by a toprope or at the very least to one of the bolts shown in the pictures. It is plain idiotic to throw yourself onto “fair” gear without other safety measuers. However, as has been pointed out, there is great utility for new leaders to discover what does and does not hold- this might not have been the safest way to do so, and it clearly does not warrant generalizations about anything whatsoever.

Still, I have intentionally taken short falls on gear with a toprope backup and clean fall line as a means of discovering how cams behave in different placements. Some held, some did not- some got tweaked. It was much more informative than bounce testing or following…

However, as has been pointed out, there is great utility for new leaders to discover what does and does not hold

And what is this great utility?

Keep it up USNAVY!!! Lets see, we now have a thread concerning your evidently poor belaying skills and, now one showing poor gear placements.

Just climb, stop filling this site with crap.

Are you kidding?

Enlighten me.

Geeze. I don't know what to say. It's self-evident. Don't you think a leader ought to know the difference between a good placement and a bad one?

Jay

Geeze. I don't know what to say. It's self-evident. Don't you think a leader ought to know the difference between a good placement and a bad one?

Jay

Of course. That’s implied. However Zxcf said "there is great utility for new leaders to discover what does and does not hold". He wrote it in the since that there is a specific technique or specific device that can determine if a placement is good. I am positive there is no device or tool that can positively identify if a placement is good or not, and beyond simple bounce testing, yanking on the cam, ect. I have never heard of any special physical action / technique that can determine if a placement is will hold (accept falling on it of course). So I am wondering what this magical utility is that he speaks of. That is unless he is simply referring to mileage / experience in which case that’s not really a utility, but a skill.

Of course. That’s implied. However Zxcf said "there is great utility for new leaders to discover what does and does not hold". He wrote it in the since that there is a specific technique or specific device that can determine if a placement is good. I am positive there is no device or tool that can positively identify if a placement is good or not, and beyond simple bounce testing, yanking on the cam, ect. I have never heard of any special physical action or technique that can determine if a placement is will hold (accept falling on it of course). So I am wondering what this magical utility is that he speaks of. That is unless he is simply referring to mileage / experience in which case that’s not really a utility, but a skill.

Of course I had a bolt clipped under the cam. I threw a two foot sling on the bolt in the first picture and placed the cam between the sling and the bolt.

Unless you are a really slow learner, the more trad placements you place (and remove), the more you get a sense of what is good/marginal/junk.
But it is interesting--your average rec climber (like me) very rarely falls on gear (I know there are plenty of exceptions, but they're not the average). I've often wondered--how good a sense does that average climber really have? Certainly there are plenty of cases of people ripping gear and getting injured/killed on moderate routes that should take good gear.

I think it's a great idea to aid climb to really get a sense of how well gear works (and doesn't), but I haven't done that myself.

Sorry for wasting anyone's time with my random musings: please resume flaming.

This is the route I placed the cam on. The red arrow indicated the approximate location where I tested the cam. If I remember right the actual location of the cam is just slightly below the end of the picture. At most it’s within a foot of that red arrow.


Of course I had a bolt clipped under the cam. I threw a two foot sling on the bolt in the first picture and placed the cam between the sling and the bolt.

Unless you are a really slow learner, the more trad placements you place (and remove), the more you get a sense of what is good/marginal/junk.