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psprings
Aug 2, 2007, 11:30 PM
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Found this article a while back... thought it was extremely helpful and insightful. It's taken from an interview by Gripped with Doug Phillips from Metolius.
This line stood out to me the most, since I consider myself an expert cam placer...
"During my tests, about one in twenty good-looking placements pulled out when loaded. The challenge is to figure out why the cam pulled, and what could have been done to prevent this from happening. "
Anyway, article in the next post, if I can get it to fit, or the link if I can't.
Peter
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psprings
Aug 2, 2007, 11:32 PM
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http://www.gripped.com/grippedemag/005/index.html
Better Beta
Cam placement rules
As the founder and head designer of Metolius, Doug Philips has spent an immense amount of time testing and improving cams over the last twenty years. Here are some tips on cam safety based on his vast experience.
Doug Phillips
1. No matter how good a placement looks, you can never be sure it will hold.
During my tests, about one in twenty good-looking placements pulled out when loaded. The challenge is to figure out why the cam pulled, and what could have been done to prevent this from happening.
To understand why cams fail, we classify pullouts into six basic categories:
Lubricants (water, dirt, dust, moss, ice)
Poor rock quality
Cam movement (walking, misaligned)
Poor placement
Cam design
Poor maintenance
Lubricants
Anything that gets between the aluminum cam lobe and the solid rock wall can act as a lubricant reducing the friction. Water is an obvious lubricant as is dirt or fine dust. A dirty seeping crack with a thin layer of moss can cause an otherwise good placement to consistently pull out.
Poor rock quality
There are three categories of rock to avoid: soft, smooth, and weak:
Soft rock tends to crush under the load of a fall. The crushed particles act as a lubricant causing the cam to slip. After this type of failure, the cam lobes will often be coated with a thin film of pulverized rock.
Smooth or polished rock will not allow the cams to grip. Smooth stone can be found in water polished cracks as well as glacier polished stone. It is very unnerving to watch a cam consistently pull out of a super smooth crack that would otherwise be a perfect placement.
Weak or fractured rock will break, causing the cam to loose traction. When a cam pulls out of seemingly solid stone, I often find a small piece of fractured rock near one of the cam lobes. Occasionally a larger chunk of stone gets blown out of the crack due to an existing fracture or weakness in the rock.
Cam movement
Cams will move from the motion of a passing climber, rope action and impact from a fall. This movement can lead to pullout failures, as the cam is no longer positioned to hold a fall. To prevent this, place the cam so it has room to move and still remain in a good camming position. A long sling will reduce unwanted movement and allow you to fall on the next piece without putting any outward tension on the lower cam. Cam pullout failures commonly occur with a sharp outward or sideways pull rather than the downward pull you had intended.
Poor placement
Wide flares, bottoming cracks and irregular rock features make it difficult to get solid cam placements. Help optimize the security of a placement by maximizing cam-to-rock contact. Place good gear before and after difficult-to-protect sections. In my tests, I have occasionally been surprised by a bad looking placements that hold when drop tested. Most of the time however, if a cam looks bad, it will pull out.
Cam Design
The brand of cam makes a difference. Metolius cams are made with holding power as the primary design criteria. The main variables are cam angle, aluminum alloy, surface contact area, and cam alignment.
Cam angle
The cam angle we use is 13.25 degrees. This sacrifices range, but increases outward force, making the cams harder to pull out.
Aluminum alloy
Our aluminum alloy is 7075 for small and midrange cams and 6061 for larger sizes. The 7075 is stronger, maintaining cam shape under load in the small sizes. This is less of an issue in the large cams, so we switch to the lighter weight, less expensive, 6061.
Surface contact area
Surface contact area is important. More surface area will create more friction increasing the cam’s security. Also, more surface area spreads the load more, improving holding power in soft or weak stone. Our Fat Cams were designed with this in mind.
Cam alignment
Maximize holding power by lining up the cam lobes with the direction of pull. The original Friends did this by using a rigid stem. The Metolius cam’s relatively stiff “U” shaped body aligns the cam lobes with the direction of pull.
Poor maintenance
Like all technical equipment, cams require maintenance. This includes cleaning, lubrication, replacing old or worn slings and repairing frayed trigger wires. Be sure to retire worn out cams.
2. Place two good cams at critical spots
Because one in 20 cams pull, reduce cam pullout by putting in a second good piece. This gives you a 99.75% chance that one placements will hold. Equalize them if possible.
3. Place the cam in as fully retracted a position as possible without getting it stuck. This is the green zone on our Range Finder system.
Tight placements help to guard against the following types of pullout:
Pullout due to cam movement
Rope movement shifts cams. Long slings help, but you can increase security by placing the largest cam possible. If the cam moves to a wider crack section it will still have good contact with all four cams.
Pullout due to poor rock quality
If the rock on one side of the crack fails the cam lobes on that side will begin to slip. A cam with a tight placement (green zone) has a better chance of holding. If the rock on both sides of the crack fails, the lobes dig into the rock. The tighter the placement, the more the cam can expand before failure.
Pullout due to lubrication
When the cam pulls because of wet or dirty conditions it will move through several inches of crack before failure. If only one side of the crack is wet or dirty, the cam lobes on the wet side will tend to slip first. If the cam is in an open position the cams on the dry side will tip out and the placement will fail. In a tight placement the cams on the dry side will not tip out, greatly increasing the chance the placement will hold. I’ve observed a tight cam placement jamming just below the original placement.
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dingus
Aug 2, 2007, 11:42 PM
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Nice posts psprings. Me and some mates travel a lot on new or rarely climbed rock, mostly granite. All of us, it seems, tends to fiddle and fuss with a lot of placements for many of the reasons cited in this article from Metolius.
Yeah that 1 in 20 out of good rock - wow. The checklist is all stuff I seem to cover routinely.
I know we're not supposed to bury cams in cracks out of courtesy to the 2nd but sometimes I feel a lubricated cam *might* have a chance of 'regaining its footing' if it has to slide through 6 inches of crack to go airborn.
Cheers
DMT
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psprings
Aug 2, 2007, 11:49 PM
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Yeah, it's a good checklist for beginners to know. I hate it when I have to brush and blow dust or lichen out of a parallel crack... makes me worry about if it'll hold if it's a nasty one.
I take the 1 in 20 as meaning passing all of the checklist stuff: good quality clean rock with a good placement and positioning, which was quite the wake up call: the risk is still there even if it all looks good.
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moose_droppings
Aug 3, 2007, 12:22 AM
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psprings wrote: : the risk is still there even if it all looks good.
Yeah, I've been on that bench for years. I still cringe when someone tells me, "that ones bomber".
One way to find out people.
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psprings
Aug 3, 2007, 2:23 PM
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Heh, I wouldn't say I cringe, but it is a good wake up call and something to always keep in mind. I've never thought twice about a good-looking cam placement before. Though I'd agree with you about "finding out"... my motto is: try to send for all your worth, fall if you can't send, hang as a last resort so you can get the route free instead of aiding!
On the flip-side, don't you hate those crumbly, grainy granite routes where after you plug your cam you're pulling on it to test it and the granite starts to crush and the cams don't stop but keep on coming out? Ugh... But at least it's still granite, and at least you're not with the crowds, aye Dingus?
(This post was edited by psprings on Aug 3, 2007, 2:27 PM)
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dingus
Aug 3, 2007, 2:49 PM
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psprings wrote: But at least it's still granite, and at least you're not with the crowds, aye Dingus?
Aye. Last Saturday's off-the-beaten-path potential FA (info spotty in this area, don't want to be presumptuous)
Nice two pitch line, hands, face and 30 feet of OW to the top.
Cheers
DMT
(This post was edited by dingus on Aug 3, 2007, 2:50 PM)
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barefoot_utah
Aug 3, 2007, 3:27 PM
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Good info even if it is from Metolious.  - Thanks Peter!
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jonqdoe
Aug 3, 2007, 3:35 PM
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dingus wrote: Aye. Last Saturday's off-the-beaten-path potential FA (info spotty in this area, don't want to be presumptuous) Nice two pitch line, hands, face and 30 feet of OW to the top. Cheers DMT
That's a great looking line. Nice find!
Does anybody have any details on how they did their testing and how large of a FF the pieces experienced? The 1 in 20 number seems high to me. It seems like there are plenty of folks out there who are more than willing to whip on their cams, and doing that with a 5% chance of a "good" placement failing seems moronic. Cool article nonetheless.
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psprings
Aug 3, 2007, 4:16 PM
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Drats! Well, I'm glad that a BD die-hard like yourself will read it, Thomas. Have fun climbing this hot rock in Utah... can't wait to get up to Washington today!
Peter
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psprings
Aug 3, 2007, 4:24 PM
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Not really sure on the testing... I saw something before (I think it was on their website) about testing in real rock. I'm not sure if that means a jig that uses real rock on the sides of it or what, but I can't find what I read before...
Yeah, it seems high to me as well. My 3rd post explains how I understood that sentence to read. But it's followed right up by the "don't" list, so maybe it was just meaning that they looked good, but that upon closer inspection they did have a problem with lubrication or other. I still think it means good... maybe people just don't fall enough.
I wish metolius would post a "testing" page on their site. They do so much freaking testing it'd be awesome to make some of their numbers and tests available to the public.
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tradklime
Aug 3, 2007, 7:11 PM
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I like some metolius cams. I have a bunch of their fat cams and a couple of super cams. Many of their design features are great.
However, I've never understood a couple things, their choice of such a small cam angle and using harder aluminum for the smaller sizes.
Cam angle: As metolius states, strength of rock is very important. Using a small cam angle increases the outward force on the rock and increases the chance of rock failure. In good rock, a small cam angle will improve the placement, but so what. Why sacrifice range and increase the chance for rock failure for a design feature that only seems to benefit a placement that would likely be adequate with a larger cam angle. The improvement in pull out force resistance would likely be in the range of forces your cams will never experience.
Cam lobe material: As metolius states, surface area contact is very important. Using harder cam lobe material reduces material deformation under load, again as metolius states. This reduces the potential surface area contact when the cam is loaded. Further, as the lobe material deforms, it can key into the irregular surface of rock, thus increasing friction.
Random thoughts brought on by your post, in combination with the alien problems and the rumored metolius release of an alien competitor.
Soft cam lobes and large range are some of aliens best features, and small range and hard cam lobes are some of metolius' worst features.
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psprings
Aug 3, 2007, 9:51 PM
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Hmm... some good thoughts.
I think the "best and worst features" tag at the end is opinion based, in my opinion :D
I would guess harder for the smaller tcus so their is less chance of catastrophic failure. My older tcus were malleable enough for my taste... that's one of my beefs with CCH... such soft metal... mushrooming and all that stuff, I'd rather have something more durable than that.
And to me, when the metolius are slotted, they stick and bite like nobodies business... I've never had that feeling with a bd. Sure, I know they're both going to hold, it just seems the metolius dig in there when sized for the crack. It does take a bit more to eye them up... maybe I don't have a problem since I own them and climb with them all the time. Probably the later.
I wonder how much more dense the aluminum on the tcus is compared to the larger cams? That's a really good observation though. Probably metolius overengineering their smaller cams. Maybe they didn't think about the trade-off that you're pointing out, or maybe they didn't think that it was significant.
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psprings
Aug 3, 2007, 9:53 PM
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Trad-
Hey, I've been wondering since I've had my Supers... did they reduce the angle on them? Doesn't seem that clear that they did or didn't on their website...
edit: Checked the website again and I guess they do... sort of surprising considering they've still got that much range.
ps- How are you liking that Medium that you picked up?
(This post was edited by psprings on Aug 3, 2007, 10:07 PM)
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jeremy11
Aug 3, 2007, 10:21 PM
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some of the reasons I feel so good over a big hex in a good constriction.
thanks for the article
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tradklime
Aug 3, 2007, 10:49 PM
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psprings wrote: I would guess harder for the smaller tcus so their is less chance of catastrophic failure. My older tcus were malleable enough for my taste... that's one of my beefs with CCH... such soft metal... mushrooming and all that stuff, I'd rather have something more durable than that.
In reply to: I wonder how much more dense the aluminum on the tcus is compared to the larger cams?
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tradklime
Aug 3, 2007, 10:54 PM
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psprings wrote: Trad- Hey, I've been wondering since I've had my Supers... did they reduce the angle on them? Doesn't seem that clear that they did or didn't on their website... edit: Checked the website again and I guess they do... sort of surprising considering they've still got that much range. ps- How are you liking that Medium that you picked up?
I like the medium quite well. I really like the supercams, other than the weight. When I carry them, I tend to take one less cam, so overall it's a weight and bulk benefit... I guess.
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bent_gate
Aug 3, 2007, 11:25 PM
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Adding to the chorus, great post.
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dingus
Aug 3, 2007, 11:43 PM
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For a long long time the mainstays of my small pro rack was a 4 x 4 of TCUs and Aliens. They complemented each other, rather than competed imo. Each seemed to fit *best* in the places where its equivalent struggled.
Maybe TCUs employ harder metals because that center cam is so critical to the holding power of the placement? My oldest TCUs I *think* may have used softer metal, the ones before they added teeth?
Anyway
DMT
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norushnomore
Aug 6, 2007, 8:45 AM
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A bit too much of Metolius self promotion.
Special safe cam angle? Like BDs are not safe.
Range marks crap?
Tight placements advice is a suspect as well. If cam is placed very tight and cannot re-orient itself it might get loaded sideways. Never mind cleaning them.
And every one out of 20 placements fails? BS in my book.
I would be ripping gear few times a year if this was true while it only happened once some 4 years ago.
Aluminum 6060 vs 7075 weight argument is lame as well: 0.098 vs 0.101 lb/cu or 0.003/0.101 ~ 0.3% diff, even on a largest cam it would be less then one gram.
What they need is a better product and not a marketing BS promoting obsolete design
(This post was edited by norushnomore on Aug 6, 2007, 11:47 PM)
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skinner
Aug 6, 2007, 10:53 PM
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psprings wrote: Cam movement Cams will move from the motion of a passing climber, rope action and impact from a fall. This movement can lead to pullout failures, as the cam is no longer positioned to hold a fall. To prevent this, place the cam so it has room to move and still remain in a good camming position. A long sling will reduce unwanted movement and allow you to fall on the next piece without putting any outward tension on the lower cam. Cam pullout failures commonly occur with a sharp outward or sideways pull rather than the downward pull you had intended.
Comment/Question
When I place a cam in a less then perfect placement, and there's a chance that it could rotate as I move or depending where I fall from, I always grab the cam and rotate it back and forth watching the lobes.
You can see if it is going to walk or if it seats itself, if I have to.. I move it around until I find I spot where it'll bite, even if it rotates.
Does anyone else do this?
An Observation
I know that no-one fiddle fcuks with gear placement more then aid climbers, but all the trad climbers I see, just plug-n-go.
I'm usually in a remote area void of other humanoids, but I noticed the trad climbers that occasionally see, don't carry a "rack" per say, rather clipping all their gear to their harness loops. With the exception of draws, they usually only have 1 or 2 slings over their shoulder which they use at the anchor. I don't know if this is because of todays gym-sport-trad climbing progression that it seems many climbers are evolving from, but what happened to using long runners to keep the rope in as straight a line as possible and to minimize a sideways pull on your protection, should you go for the big hoopla?
Metolius Cams
My metolius cams don't always fit in weird cracks, but when I do plug one in, I know it's bomber, and 9x out of 10 is what I build anchors with.
Btw.. great article/post
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moose_droppings
Aug 6, 2007, 11:18 PM
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I agree, 1 out of 20 is a stretch. Maybe if 1 out of 20 is bad.
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