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patto
Jun 15, 2009, 4:35 AM
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Absolutely fantastic work Aric. Very comprehensive. I hope you are finding some time for relaxationa and most importantly climbing despite all this! :-)
EDIT:In some ways I think most of the usual suspects around the Lab have said their piece on this issue. That said there are a few other forums that this is spreading to now that brand new cams have failed. Its good to get the word out.
(This post was edited by patto on Jun 15, 2009, 7:02 AM)
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marc801
Jun 15, 2009, 5:06 AM
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patto wrote: Absolutely fantastic work Aric. Very comprehensive.
The short version of all this: replace your Aliens with almost anything else. Don't buy any new Aliens. Don't trust any Aliens.
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josephgdawson
Jun 15, 2009, 8:52 AM
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I cannot draw the conclusion that we should replace all of our Aliens from the results in this test.
I do not see any problem with cams pulling out of the fixture below their strength rating (that is, slipping out of the device). Correct me if I am wrong, but I would guess rock has a higher friction coefficient that the metal he is using in his rig to hold the cams while pulling on them. In fact, the flattening of the lobes under heavy loads could make the cams stick better in rock. The flattening could prevent rock from breaking.
I think a summary of the failures that are not due to slippage would be more fair and of more use than counting slipping as a failure.
Please correct me if I am wrong, but excluding failures due to slipping out of the rig leaves us with Sample 3 and Sample 7. In my mind these are the more disturbing failures. Sample 3, a used Yellow Alien, had its head pop off at 77.7% of its rated strength. Sample 7, a new Black Alien, slipped out of the rig in the initial test and then the stem failed in the stem test at 6.64KN, while the unit is rated at 8.27KN. As disturbing as these failures are, it should be noted that the Yellow Alien was used and the stem on the Black one failed below its rated strength after it had already gone through one test.
I think it is fantastic that adatesman is doing these tests. Thank you adatesman. I think adatesman did a great job in reporting the information in a standardized and transparent manner. The more data the better.
Adatesman, I must take issue with you being the one to moderate this thread when you are the one who performed the test and posted the results. I think it would strengthen the integrity if this thread if you turned the moderation of it over to a third party who may be more objective and would be less prone to taking any criticism of the test personally.
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patto
Jun 15, 2009, 10:35 AM
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Excellent post josephgdawson.
josephgdawson wrote: I do not see any problem with cams pulling out of the fixture below their strength rating (that is, slipping out of the device). Correct me if I am wrong, but I would guess rock has a higher friction coefficient that the metal he is using in his rig to hold the cams while pulling on them.
That said notice the axle bending in most of these cases. It is this axle bending combined with significant lobe flattening that REDUCES the force applied to the lobes and thus reduces friction.
Furthermore notice the aliens that don't slip out. Most of these survive without bent axles and maintain a linear force graph. It seems clear to me the bending of the axle contributes significantly to the slipping out.
josephgdawson wrote: I cannot draw the conclusion that we should replace all of our Aliens from the results in this test.
josephgdawson wrote: In fact, the flattening of the lobes under heavy loads could make the cams stick better in rock. The flattening could prevent rock from breaking.
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blondgecko
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Jun 15, 2009, 10:55 AM
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josephgdawson wrote: Correct me if I am wrong, but I would guess rock has a higher friction coefficient that the metal he is using in his rig to hold the cams while pulling on them.
Coefficient of friction between aluminium and mild steel: 0.61
Coefficient of friction between aluminium and rock: varies, but around 0.3 on average
Draw your own conclusions.
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adatesman
Jun 15, 2009, 11:32 AM
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mojomonkey
Jun 15, 2009, 1:00 PM
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A couple quick questions on method:
- Were the hybrids also tested in a "parallel" placement, or were you able to angle the plates on your fixture so both sets of lobes were ~ 50%, or split the difference such that one set is more cammed and one set less cammed?
- You pulled the cable loop directly, rather than the sling. Any thoughts on the impact of this? Black Diamond states, in the Camalot booklet that "Clipping directly into the wire loop with a carabiner can reduce the strength of the unit by up to 2 kN (450 lbf)."
- Can you document what the texture on your fixture is versus the min/max from the specification? I know I read it in another thread, but don't want to scan through that monster...
For what its worth, from an prior exchange with Dave Waggoner at CCH, the letter stamped on the head indicated who did the testing. I don't know if the tester is normally also the person who performed the brazing or not. Scanning through, it looks like all of the new units were tested by the same person, indicated by the "W" stamp.
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adatesman
Jun 15, 2009, 1:24 PM
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sethg
Jun 15, 2009, 1:47 PM
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Just FYI, regarding the clipping of the cable loop vs. the sling: In the instructions that come with tcus Metolius gives similar warnings. Metolius warns that clipping directly to the device instead of the sling reduces the strength. I have no idea why either.
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kennoyce
Jun 15, 2009, 2:28 PM
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Thanks for all of the hard work. As always I loved the report.
Just a note on the reduction in strength by clipping to the cable instead of the sling. The only reason I can think of a reduction in strength would be the tight bend of the cable around the biner rather than having the load distributed over the width of the sling. If this is the case then the weak point would be the attachment point of the carabiner. Since none of the cams tested failed at this point, the tested strengths shouldn't depend on weather it was loaded with the sling or with a biner.
Just a thought.
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shimanilami
Jun 15, 2009, 3:52 PM
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Great work, Aric. But I don't think it will change anyone's mind about Aliens. (I, for one, am still a fan.)
Have you done these same studies with other cams? Now that we know how good/bad the Aliens are, I'd like to see how others compare.
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adatesman
Jun 15, 2009, 3:59 PM
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jt512
Jun 15, 2009, 5:23 PM
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Aric, this is great work. Thank you for undertaking this monumental project. I have a couple of questions. Excuse me if they have already been asked; I haven't read the whole thread.
First, a question which naturally arises reading through your results is how do Aliens compare with other brands. I realize that you may have not undertaken a systematic study of other brands, and that to do so would likely be prohibitive in terms of time and cost. However, the question of mislocated axle holes is highly dependent on the accuracy of the software used and the skill of the person using it, and so, I think that presenting results of this measurement from other brands for comparison will help put the Alien results in context. Either other brands will also be found to have mislocated axle holes, or they will not. If they do, then that will either mean that all cams are equally bad in this regard, or that the measurement procedure is unreliable. If they do not, then presenting the results will strengthen the case that the problem is unique to Aliens.
The second question has to do with the presentation format. That is a lot of material to read in an online forum format. It would be much easier to read and digest if it could be downloaded and printed out. Any chance that you could compile this into a pdf and put it on a website (maybe this one, but not necessarily) for download. I could always host it on my web server.
Relatedly, it would also be nice to have the data in a data base (or at least a spreadsheet) to facilitate analysis. In the present "flat" format, even simple questions like "what percentage of tested cams were marked 'tensile tested'?" or "how do results compare for 'tensile tested' Aliens vs others?" are laborious to answer; whereas, if the data were in a spreadsheet, the answers would be only a few mouse clicks away.
Jay
(This post was edited by jt512 on Jun 15, 2009, 7:09 PM)
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shoo
Jun 15, 2009, 6:05 PM
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Can you also put this on the front page under the Destruction Theater? I think it deserves a place there.
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qtm
Jun 15, 2009, 6:52 PM
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jt512 wrote: However, the question of mislocated axle holes is highly dependent on the accuracy of the software used and the skill of the person using it, and so, I think that presenting results of this measurement from other brands for comparison will help put the Alien results in context. Either other brands will also be found to have mislocated axle holes, or they will not. If they do, then that will either mean that all cams are equally bad in this regard, or that the measurement procedure is unreliable. If they do not, then presenting the results will strengthen the case that the problem is unique to Aliens. Jay
I scanned in 28 cams. 9 Aliens, 7 BD Camalots, 8 Tech Friends, 2 WC Zeros, and 2 Master cams. I did multiple photographs of each since the first couple of times I wasn't sure if I were doing it right, and had some problems with rounded edges showing up as the lobe. This was primarily resolved using manual points.
In the end, all the Aliens show up as off-center. All the other cams are fine... except one BD C4 .3 cam.
I don't know why, but it always comes up off center; depending on how many points I pick, the center wanders around a bit. Close, but I can't get it to fit as easily as all the rest.
It's possible that the lobe is a little deformed, it might be one that I had to remove with the help of a nut tool and a big rock. The interesting thing is that the lobe on the other side scans in fine. That leads me to believe the software works as advertised.
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adatesman
Jun 15, 2009, 7:29 PM
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healyje
Jun 15, 2009, 9:54 PM
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It would take some work and expense, but I would think it would be possible to make a statically-positioned test jig that is epoxy-faced with rough, natural granite from a headstone / countertop company and to also angle the bottom of the jig in a degree or two so it isn't dead parallel - and then do a dynamic drop test. That would be about as close to real-world conditions as you could get. Would likely take some financial assistance and time, however.
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angry
Jun 15, 2009, 10:08 PM
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I hate to be that guy but...
If anything, these tests have given me confidence in well placed newer aliens. I thought my old ones were fine but was leery of other peoples.
It appears that in most cases, the braze is quite good. The failure from your fixture isn't too realistic and is still more than enough.
There is some reworking of published ratings that need to be done and the cam axle hole thing needs to be addressed. In regards to falling on them and getting caught, they look good.
I am also inclined to think that the axles bend when the lobes slipped out, not that bending axles caused the lobes to slip. Look at the axles of the ones that didn't slip.
What do you suppose the heads would have held if the lobes hadn't slipped out?
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philbox
Moderator
Jun 15, 2009, 10:26 PM
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adatesman wrote: josephgdawson wrote: Adatesman, I must take issue with you being the one to moderate this thread when you are the one who performed the test and posted the results. I think it would strengthen the integrity if this thread if you turned the moderation of it over to a third party who may be more objective and would be less prone to taking any criticism of the test personally. FWIW I'm not the only Mod here in The Lab, just the one who happens to spend the most time here. I've asked the others to help keep an eye on this since I completely agree there's the potential for inappropriate use of powers. The only modding I did in the last thread was hiding a couple off-topic/silly posts in the first couple pages and banning the CCH shill after discussing it with the other mods. While these actions may have not been transparent to the general user base, everything was discussed at length in the Mod forum before being done.
There is at least one other mod who is keeping a very close eye on this thread, me. Aric is not doing this alone. He does take the lead in this thread which is right and proper given that it is his area of expertise. There has been much discussion on the mods forum as part of the oversight of Aric's modding within this forum. Aric is doing an awesome job here particularly given the subject matter. I and in fact all the mods and the management of this website have complete confidence with Aric.
What also should be noted is that this website has a policy of complete transparency as to mod actions. Nothing is deleted. We track and audit actions. This ensures that mods actions are reversible if it is thought that the action is not correct. Of course most actions are telegraphed back to the user via the PM system. We do however simply ship off to the recycle bin any scammer or spammer posts without referral to the scammer/spammer.
Aric's actions as a mod do in no way negate his work with this subject.
Bact to the topic at hand then.
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jt512
Jun 15, 2009, 11:09 PM
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adatesman wrote: jt512 wrote: The second question has to do with the presentation format. That is a lot of material to read in an online forum format. It would be much easier to read and digest if it could be downloaded and printed out. ... I'm almost done with it and will post a link to the PDF when its finished (currently resizing pics to knock it down from 110 pages).
Yikes! Sounds like a good idea.
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curt
Jun 16, 2009, 12:02 AM
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philbox wrote: healyje wrote: It would take some work and expense, but I would think it would be possible to make a statically-positioned test jig that is epoxy-faced with rough, natural granite from a headstone / countertop company and to also angle the bottom of the jig in a degree or two so it isn't dead parallel - and then do a dynamic drop test. That would be about as close to real-world conditions as you could get. Would likely take some financial assistance and time, however. To what purpose would this test jig be of use. There would be no way that any test would be repeatable. Rock is way too varied even individual pieces. The only true test is to make the test as repeatable with consistent materials that the test jig is made out of i/e steel with a known pattern.
I agree. While you might get some additional insight into how the cams perform against that particular rock type, the CE/UIAA ratings and tests are done with textured steel plates. So, it certainly seems best to stick with those.
Curt
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adatesman
Jun 16, 2009, 12:08 AM
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yokese
Jun 16, 2009, 12:32 AM
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jt512 wrote: Relatedly, it would also be nice to have the data in a data base (or at least a spreadsheet) to facilitate analysis. In the present "flat" format, even simple questions like "what percentage of tested cams were marked 'tensile tested'?" or "how do results compare for 'tensile tested' Aliens vs others?" are laborious to answer; whereas, if the data were in a spreadsheet, the answers would be only a few mouse clicks away. Jay
I had a bit of free time and already started parsing the previous page into a excel file (or any other program that accepts csv files). I can upload it to the internet and share with anyone interested.
Edited: Not gonna do it. Adatesman is gonna upload his data file. (next post)
(This post was edited by yokese on Jun 16, 2009, 12:52 AM)
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