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adatesman
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May 28, 2009, 8:10 PM
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The topic of mis-centered axle holes is something that's been on my mind a lot lately and it was touched on in the Alien Failure thread, so I figure I may as well start a thread for it.
Long story short: all sorts of screwy things happen to the cam angles if you allow the lobe to rotate around a point other than the center point of the logarithmic spiral. Depending which direction you go, this screwiness can result in a nice, smooth increase in effective cam angle or a lobe that has an effective cam angle that drops to almost nothing either at the extremes of the lobe's rotation or somewhere in the middle. The math is kind of fun, so I'll leave it to whoever is interested to go play with it rather than charting it all out for you here. The one hint I'll give is that there are 4 directions you can go, the boundaries between those directions are not perpendicular to one another and 3 of the 4 of them result in bad things happening to the effective cam angle.
Anyway, as I mentioned in the Alien Failure thread one of the people who came out of the woodwork and contacted me is a guy by the name of John Field. He's the guy who invented the Supercam, but more importantly he wrote a program a while back (when some Aliens with mis-drilled axle holes were discovered) that allows you to take a picture of a cam and see if the axle hole is properly centered in the spiral. Its wicked cool and available online at DorringtonClimbing.com.
Since I was up at Rock&Snow in New Paltz, NY to do some testing of gear I figured I may as well take some pics to run through this software and see how things turn out. Unfortunately the software is a bit limited in what cam angles it works with, so I limited the photos to cams that use angles listed in the software (13.25- Metolius, 13.75- WC, 15.00-BD, 16.00- CCH).
Except for the #6 WC Zero, all of the cams pictured below were brand new and hanging on the rack at R&S. For the software to work correctly in automatic mode you need to make sure that the rearmost lobe is hidden in the photo, and I didn't notice that it wasn't in the photo of the #5 Zero until I got home. My #6 Zero is practically unused, so I tossed it in for comparison as well.
To be honest, there really isn't much exciting to see with the cams from BD, Metolius and WC as the center of the axles match the calculated centers of the spirals pretty well. The CCH Aliens though.... Not so much. As I mentioned above, working though the math is a worthwhile project. Otherwise grab a protractor and ruler and with a bit of doodling you can see what's going on in a case-by-case basis. Even better, take some pics of your cams and run them through the software. The results may surprise you.
Oh, and a couple notes about the pics and results:
- I don't know how the software handles parallax error in the photo (camera not centered on the axle, which makes things at different depths appear shifted), so that may have a minor effect on the positioning of the center point.
- I don't know for certain that this software is reliable or functions properly. I tend to think it does based on the credentials of the guy who wrote it and it lining up correctly on the lobes from WC, BD and Metolius, but I have not independently verified its results.
- I have no idea why, but 2 of the Aliens were assembled with the slot for the springs on the top and the other 11 with the slot on the bottom. Given how the lobes load the axle having the slot on top seems a much better idea to me, but I don't know if there's a reason they usually put it at the bottom.
- There's 2 pics for each of the Alien Hybrids since there's different sized lobes on each side.
- Feel free to click on any of the pics for a larger version.
- I've been trying to send CCH the data from this and my testing on Tuesday, but their email box has been full and the messages keep bouncing. I'll keep trying in case anyone happens to call them kindly ask them to clear it out so my email with the data can go through.
Black Diamond #3 C4, date code 8347A:
Black Diamond #3 C3, date code 8271A:
Metolius #5 Powercam, date stamp 9/07:
Metolius Orange Mastercam, date stamp T8 2008:
Metolius Medium Supercam, date code A 3/08:
Wild Country #1 Tech Friend, date code 828:
Wild Country #5 Zero, no date:
Wild Country #6 Zero, no date:
CCH Black Alien, date stamp 408:
CCH Yellow Alien, date stamp 509:
CCH Yellow Alien, date stamp 509:
CCH Yellow Alien, date stamp 509:
CCH Grey Alien, date stamp 409:
CCH Grey Alien, date stamp 409:
CCH Red Alien, date stamp 509:
CCH Red Alien, date stamp 509:
CCH Purple Alien, date stamp 1108:
CCH Purple Alien, date stamp 1108:
CCH Clear Alien, date stamp 508:
CCH Red/Clear Hybrid Alien, date stamp 1008, side 1:
CCH Red/Clear Hybrid Alien, date stamp 1008, side 2:
CCH Red/Clear Hybrid Alien, date stamp 1008, side 1:
CCH Red/Clear Hybrid Alien, date stamp 1008, side 2:
(This post was edited by adatesman on May 30, 2009, 5:20 AM)
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glytch
May 28, 2009, 9:50 PM
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Wow. Thank you for taking the time to do this.
That's disturbing.
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healyje
May 28, 2009, 10:23 PM
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glytch wrote: That's disturbing.
Yep, or in other words - toss CCH's cam angle completely out the window as it isn't happening unless the axle hole is drilled in the designed location.
We've focused on the brazing in the past as that alone should have been enough to convince folks of the sad reality of their [lack of] manufacturing execution. But that apparently wasn't enough - anyone in denial after reviewing these and other issues such as swaging failures should have their head examined.
Dudes - look at those pictures! Drilling the axle holes in the right place ain't rocket science - if they can't manage something as simple as that do you really want to trust your life to their gear? Would you trust a belayer who got it right some of the time, but in even a small random sample of observing their belaying it turned out they were grossly failing most of the time?
And considering they are failing in multiple modalities: brazing, drilling, swaging, slinging, color coding, and cam lobe assembly - what are the odds of a cam coming out of CCH properly assembled and safe to use? 'But dude, they stick like glue...!' - well yeah, if you're lucky enough to get one of the good ones.
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agdavis
May 28, 2009, 10:37 PM
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jeez that's just plain scary. thank you for taking the time to do this!
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atlnq9
May 28, 2009, 11:19 PM
Post #5 of 139
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3 out of 15 13 of the aliens are close enough. So what do they do right all of the time? Maybe use the right color coding? Geez!
Edit in bold
(This post was edited by atlnq9 on May 28, 2009, 11:24 PM)
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healyje
May 29, 2009, 3:15 PM
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Aric, just shipped out one like-new set of four Alien hybrids (one of my two sets), give'm hell, I'll be curious to see what they pull at and how the axle holes line up (or don't).
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giza
May 29, 2009, 4:21 PM
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Healyje, usually your posts are annoying as shit but in this case I really can't argue with your logic. Drilling the axle holes in the correct location shouldn't be a process with variable results like those in the photos.
I was a staunch defender of Aliens despite their previous problems, had all my Alien cams tensile tested by CCH, and then continued to climb on them but am now considering retiring them - at least for free climbing.
I gotta admit though, they place so well and I've put so much faith in them for years it's hard to let them go.
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billl7
May 29, 2009, 4:26 PM
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"The topic of mis-centered axle holes is something that's been on my mind a lot lately and it was touched on in the Alien Failure thread"
A historical note (might be something well known):
CCH responded awhile back to some mis-centered axle holes ... back around the same time of the first recall I remember that was due to braze failures. Perhaps that is in the thread that you mentioned. I don't have time to go search right now.
As I recall pretty clearly, they did not try to recall those cams indicating that it was just a range issue. They did say they would replace any that were returned.
Perhaps something worth following up:
In one thread at the time, I and others emphasized that it could definitely be more than a range issue, that it could well affect the cam angle - as you noted - and so ability to hold a fall.
I wonder ...
* whether an analysis of some of these would reveal that more than range is involved;
* whether the dates on these ones are after the date that CCH first acknowledged the mis-aligned axle holes.
Bill L
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basilisk
May 29, 2009, 4:31 PM
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....damnit Aric. I just recently started buying aliens to replace my other small cams. I was able to write off RC.com as being overly alarmist. Then your tests had me a little concerned, figured I need to bounce test 'em something serious. This was the cherry to make me properly nervous.
Off to take some pictures....
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healyje
May 29, 2009, 4:32 PM
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giza wrote: Healyje, usually your posts are annoying as shit...
You're welcome, I'd hate to think I was slipping...
I still have one set of hybrids and only use them for free climbing and it sucks to have retired them with no real replacement yet. But at some point rational people have to accept reality, weigh the obvious risks, and make a judgment call - in this case it's, unfortunately, a no-brainer.
We're lucky folks have only been injured up to now and not killed. I wouldn't have changed my stance on CCH and Aliens if they'd bothered putting in even a modicum of effort (and communication) into addressing the situation anywhere along the way. That it [culturally] just escapes them is sad, but peoples' lives are literally hanging in the balance and a manufacturer like them does no one any favors - not themselves, us as climbers, the sport, or the industry as a whole - it makes us all look wreckless in the eyes of the law, regulators, and the public at large. This sort of thing just invites lawyers and the regulatory-inclined.
(This post was edited by healyje on May 29, 2009, 4:37 PM)
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k.l.k
May 29, 2009, 4:40 PM
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healyje wrote: We're lucky folks have only been injured up to now and not killed. I wouldn't have changed my stance on CCH and Aliens if they'd put even a modicum of effort into resolving the situation anywhere along the way. That it [culturally] just escapes them is sad, but peoples' lives are literally hanging in the balance and a manufacturer like them does no one any favors - not themselves, us as climbers, the sport, or the industry as a whole - it makes us all look wreckless in the eyes of the law, regulators, and the public at large. This sort of thing just invites lawyers and the regulatory-inclined.
Exactly-- that's the only frickin reason I even bother to read these threads. Climbing is so marginal in the US anyway, and folks have beomce so accustomed, in gyms, to getting "licensed" before they're allowed to climb, and so few of them have any outdoor competence--
It's really bad for all of us when a good designer in the industry can't respond to obvious and repeated problems.
I am so frickin' sick of hearing about this frickin stuff.
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healyje
May 29, 2009, 4:46 PM
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billl7 wrote: CCH responded awhile back to some mis-centered axle holes ... they did not try to recall those cams indicating that it was just a range issue.
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adatesman
Moderator
May 29, 2009, 5:26 PM
Post #13 of 139
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basilisk wrote: .I was able to write off RC.com as being overly alarmist.
In general, quite possibly. But I tend to toss alarmist sorts of things out of The Lab and if its from me I absolutely have data to back it up. I would have picked a different site to post my results, but The Lab here on RC seemed the best fit and got the best response, so there you go.
Sorry to make you doubt your purchases and FWIW I don't think its a bad design, just poor execution. Check the centering of the spiral, get them proof tested and then climb on.
-a.
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dudemanbu
May 29, 2009, 5:49 PM
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I would just like to say that I called this like 4 years ago, and also that everyone jumped down my throat to defend CCH.
Told ya so.
That is all.
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bill413
May 29, 2009, 7:52 PM
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adatesman wrote: Sorry to make you doubt your purchases and FWIW I don't think its a bad design, just poor execution. Check the centering of the spiral, get them proof tested and then climb on.
When Aliens are good, they're great. But it's the QC/execution/reliability that's my concern.
They are not a bad design. People love them. When they are good they are great.....it's just...how do we know they are good?
Sigh. I don't feel good about a company that understates the loads its cams will withstand, etc....
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shockabuku
May 29, 2009, 8:26 PM
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bill413 wrote: adatesman wrote: Sorry to make you doubt your purchases and FWIW I don't think its a bad design, just poor execution. Check the centering of the spiral, get them proof tested and then climb on. I think that this is something that needs to be brought out more in the debate. When Aliens are good, they're great. But it's the QC/execution/reliability that's my concern. They are not a bad design. People love them. When they are good they are great.....it's just...how do we know they are good? Sigh. I don't feel good about a company that understates the loads its cams will withstand, etc....
Maybe they quote the loads that a properly manufactured and assembled cam will hold.
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healyje
May 29, 2009, 8:34 PM
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bill413 wrote: People love them.
I understand, really I do. I also love the climb I've been working on for the past two years - but one wrong move on a climb as serious as it and I'll be dead in a heartbeat. Both are a matter of acknowledging reality and working with the cards you've been dealt; working with what is in your control and minimizing the risk of those things which are not. The manufacturing execution of Aliens is not something we control; how, and if, we use them on the other hand is.
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rschap
May 29, 2009, 10:30 PM
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Not to say the center point isn’t off but you really can’t tell from a picture. We’ve tried taking pictures of items that we need to water jet and no matter how you zoom or angle the camera there is a slight skew and things don’t line up quite right.
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healyje
May 29, 2009, 11:18 PM
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rschap wrote: Not to say the center point isn’t off but you really can’t tell from a picture. We’ve tried taking pictures of items that we need to water jet and no matter how you zoom or angle the camera there is a slight skew and things don’t line up quite right.
Hmmm, that's quite a statement. Lens axis lined up with axle axis - pretty much a done deal and more than accurate enough for the purposes of this piece of software. Not sure why your folks can't line up a lens axis perpendicular to a piece of work inline with a specific target. Here if you can't see any of the sides of the cam lobe, it's good. Again, at these scales it's plenty accurate for identifying the the center of the design center of axle axis well enough to know whether they blew it or not.
If you work with metal, then what are the odds you'd be mis-drilling axle holes over and over again with a completely random drift from design location of the axle?
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adatesman
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May 30, 2009, 5:15 AM
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rschap wrote: Not to say the center point isn’t off but you really can’t tell from a picture. We’ve tried taking pictures of items that we need to water jet and no matter how you zoom or angle the camera there is a slight skew and things don’t line up quite right.
That would be the parallax error I mentioned in Note #1. Given the relatively short distance between plane at the top of the nut and the top surface of the lobe the error will be small, but present. I don't know if the software takes it into account (if at all), hence pointing it out in the OP. As long as you line up on the axle the parallax will be small and any skew will be on the curve and the calculated center shouldn't be effected. The skew will effect the points of the curve, but that will be reported in the maximum outlier and RMS error reported for the fitted curve.
Which brings up another important point that I'll edit into the OP- I don't know for certain that this software is reliable or functions properly. I tend to think it does based on the credentials of the guy who wrote it and it lining up correctly on the lobes from WC, BD and Metolius, but I have not independently verified its results.
(This post was edited by adatesman on May 30, 2009, 5:20 AM)
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glytch
May 30, 2009, 6:24 AM
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adatesman wrote: ... I don't know for certain that this software is reliable or functions properly. I tend to think it does based on the credentials of the guy who wrote it and it lining up correctly on the lobes from WC, BD and Metolius, but I have not independently verified its results.
Not that you have the time (completely understandably!), but if you've got software that builds logarithmic spirals, you should be able to print out the shell of a cam with no centerpoint attached (lest the software is identifying a circle and marking its middle), identify the centerpoint of that cam using the software, and compare that to the actual centerpoint (which you know since you built the thing).
Seems like as good a way as any of testing the software...
G
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adatesman
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May 30, 2009, 7:06 AM
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That's exactly what my plan was... I just haven't motivated to turn on the printer yet.
Oops, misread your post. I thought you were suggesting printing out a spiral and then comparing that to its results. I like your idea too and will do that momentarily. FWIW I've kind of already verified it this way by running one of my cam lobes through it... I generate my curve in Mathematica and then import that into Solidworks for the modeling and then into Mastercam for the machine code. I know for a fact that my lobes are correctly centered and the software identified it correctly.
I'm also going to drop the guy who wrote it an email to see what he's done to verify it, which is what I'm doing presently.
Ooo... I could just do a screen capture of one of my solid models... That would be super quick and easy. I'll do that and post it momentarily.
(This post was edited by adatesman on May 30, 2009, 7:12 AM)
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rschap
May 30, 2009, 7:14 AM
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Yeah, I caught that in the op, I was just saying in my experience using 3 different cameras on several different parts we have taken pictures and then traced the picture in Acadd, every time the part has come out longer or shorter than the original part. On non critical artistic parts we use this method a lot. The purple and the clear aliens are what first caught my attention, you can see that they are obviously skewed, and several of the other aliens don’t line up properly on the outside lobe. Could this be because they use a 16 degree caming angle and the others don’t?
I’m not arguing about whether or not the holes are centered, I’m just pointing out the flaws I can see in this process to have a discussion about it and to clarify what the margin of error is so I can make a more informed decision. If they are drilling the holes by hand without a properly set up jig I would say there is absolutely no way they are getting them centered.
I’d also like to point out that the WC #6 is turned to the right and the center is slightly to the left, while the WC #5 is turned to the left making the center point slightly to the right. So it seems that the program does get the center point pretty damn close even with a slight skew.
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adatesman
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May 30, 2009, 8:12 AM
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Ok, I ran a couple models through and it's looking pretty darned good provided you manually select the points rather than let it detect them (which is what I did for all of the images above).
Here are three of the same 16 degree cam lobe model I happened to have done up in Solidworks that show the effect of skew. Seems to me a better way to get the pics would be in a scanner, which would be somewhat troublesome without first taking the cam apart. Conveniently I took the Aliens apart yesterday so I think I'll scan some of the non-mangled lobes and see if it makes a difference. This won't be until after I get the pull test results posted though, so it might not be until the end of the week.
Anyway, here's the lobe straight on. Sorry about the crappy pics; they went all to hell when the software resized them.
Same lobe rotated a bit:
Same lobe rotated a lot:
I guess what I take away from this is that large amounts of skew will screw with it pretty bad but small amounts not so much.
BTW, if anyone would like the original pics that I used for any of this just let me know and I'll send them along.
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16_deg_lobe_skewed1-error.JPG
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helios
May 30, 2009, 8:46 AM
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Aric,
Can you verify whether the holding power [and therefore cam angle] is constant in these misdrilled aliens? Maybe by seeing how much force is outwardly applied when pull tested at various degrees of retraction in its range? Not sure if you are set up to measure the outward force of cam loads. I'm not just talking about holding power in a vice, tested to failure. This seems like a good way to verify the software - since shouldn't you be able to predict how the cam angle will be affected if misdrilled in a certain direction?
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