UKC

I didn't want to speculate further on an accident that may have been partly due to a cam ripping hence a new post.

How many people unreservedly trust cam placements? Personally I only tend to use them when nothing else will fit especially on limestone. I have seen too many apparently well placed cams fail, again usually on limestone which is what I tend to find myself climbing most frequently.

What is your experience?

Al

In reply to GridNorth:

In my experience I've seen probably ten times as many nuts fail, or simply lift out, than cams. However this might be due to the occasional dodgy partner, or more nuts being placed in general than cams. I more often have cams so wedged they won't come out (easily), as opposed to having them fail (much to my seconds' frustration ), but possibly due to overcompensation.

In reply to Robin Woodward:

My main issue with cams is that they can look good but still fail and you have no way of knowing till you fall. A well placed nut looks good, feels good and in my experience invariably is good. It often surprise me how many "marginal" placements hold a fall.

Al

In reply to GridNorth:

I haven't seen that many cams fail, but I've seen a fair share of nuts pop out.

But that might as well be, that granite and the alike just happen to suit cams more than nuts. Come to think of it, I generally place cams these days (quicker to place and clean) and so do a lot of others. So nuts only come out on clear places for them (and no cams nearby)... or when the correct cam is already used, so they can be sub-optimal thus more prone to coming out.

In reply to GridNorth: I don't have a problem with cams in good placements. If they're in bad placements I treat them with as much caution as I would with flared, scratchy nut placements. I climb mainly on granite and metamorphics, so I'm curious why they should pop out on UK limestone, or why you think they do.

Don't suppose you have any photo's of 'good' placements that you think would fail?

In reply to GridNorth:

I think an understanding of how cams actually work during a fall is required in order to place them correctly. some people do seem to view them as magic and assume that if they don't fall out when initially placed that they must be bomber.

In reply to GridNorth:

I believe this phenomenon is termed Schrödinger's cam. You don't actually know whether the cam is good or bad until you actually fall on it

In reply to HeMa:


Do you mean when shock loaded during a fall, or at other times? I think it's worth making that distinction, because a cam should have some degree of grip when unweighted and is therefore less likely to lift out due to ropes pulling on it in various directions.

In reply to GridNorth:

Probably true IF the person placing them knows what they are doing. I often encourage novice leaders to set their nuts a bit more forcefully to make sure they are nicely seated after seeing far too many lift out/wobble about to an inferior placement.

In a perfect placement a cam is pretty straightforward (and probably bomber). In anything other than perfect placements I find cams often as fiddly as nuts. I've never quite liked any of the cam placements I've used in Sennen for example; probably fine but very crystal-dependent and you have to fiddle around to get all four cam lobes in good places.

In reply to wbo:

I don't have any photos but I recently placed one in the Avon Gorge, a 0.4 BD Camalot. It looked good. Not over cammed, not under cammed in fact a perfect placement and just the sort of slot they were designed for. I tugged it, as hard as it is possible whilst hanging on with the other arm, and it felt secure. I was unsure however so I down climbed. As soon as I pulled it with a little more force from the ground it popped out. Admittedly some of the Avon Gorge rock is especially smooth in texture.

Al

In reply to GridNorth:

I prefer to trust a well placed nut anytime, particularly on limestone.

In reply to GridNorth:

I go with the (possibly mistaken?) assumption that if the cam doesn't move when I tug on it, it won't fail due to friction. If it's also in good, solid rock I'll therefore trust it. If the rock is iffy (including things like sandstone where the surface can 'fail') I'll treat it with more suspicion, or avoid placing it to begin with.

In reply to bpmclimb:

I mean during loading, shock or slower (eg. when lowering).

But as said, most of the times the placements have been not optimal. And as stated to rock I mainly climb on, happens to favor cams instead of nuts. It's either pretty non constricted cracks, or one with big crystals makin' nuts hard to seat well, difficult to clean and also the only thing keepin' 'em in place is said crystal, so dodgy placement by all accounts.

In reply to andrewmcleod:


But with cams, you're not solely trusting the said crustals to hold them in, where is quite often it will be the case with nuts.

Of the half a dozen or so routes I climbed in Sennen, I didn't find gear (mainly cams again) all that fiddly. And they certainly felt better than nuts. The granite in Sennen reminded me quite a bit of the one found in Paradiset in Lofoten btw.

In reply to andrewmcleod:


generally the issue isn't that the nuts need tugging forcefully its that they need extending appropriately.

In reply to GridNorth:

All of this theorising is fine but how many of you have actually put cams to the test. For me I think the crux of the matter is the issue of cams and limestone. Quite often with grit and granite there is no other option available and on the basis that anything is better than nothing in they go.

Al

In reply to GridNorth:

I have fallen on and lowered off cams on several occasions on most rock types and never had one fail. I held a whipper on to a cam in Pembroke last weekend at mother carey's, when took over the lead and got to the cam I was shocked at how poor it was.
However I do have limited confidence in them on highly polished limestone.

In reply to joem:

google youtube cam failure pull out climbing

youtube.com/watch?v=DHjNxgbAhQM&
youtube.com/watch?v=MW1teH6k9xo&
youtube.com/watch?v=O9gM1J14t2k& (rock breaks)
youtube.com/watch?v=GQ854rwQZUI& - lots of failues

also see http://www.ukclimbing.com/forums/t.php?t=562169

In reply to GridNorth:

gear on limestone is trickier. Lower friction of the Rock and funky shaped cracks ate likely reasons.

However...Cams rip usually because people place them in a hurry. limestone is steep so people are usually in a hurry. A friend broke her back (all OK now) when a wire popped at stoney. She's a superb climber and slumped on to it and in hindsight blames laziness in not ensuring there was more kit between her and the floor.

There seems to be a significant number of accidents when people take a rest and the gear turns out to be inadequate. There has been at least 2 accidents at London Wall for example.

Trad leading near your limit is dangerous.

In reply to joem:

I second this. I've taken decent falls on cams and never had one fail. Three of these were large ish falls on limestone (two where a knowingly poor nut above ripped). However, none of these were in dodgy polished sided or flaring cracks, where i'd normally backup/overcam/find elsewhere if it looks dodgy. I have had cams fall out due to ropedrag etc., but this is often knowing they were poor in the first place (normally small cams protecting a crux move which won't work once I'm above them and I haven't wanted to extend).

In reply to alasdair19:

Agree, limestone is a bit of an anomaly. I will usually go to wires first on it and cams as a last resort. That said, they're usually fine, a tiny cam of mine held repeated falls of mine at High Tor the other day.

In fact, not sure I've ever had a cam rip. I've had them hold several times in distinctly poor placements instead. On grit a good cam placement is as bomber as any wire.

In reply to CurlyStevo:


Maybe cams are most useful to hang as weights on the QDs to stop the nut lifting out

In reply to spidermonkey09:


Me too, generally. Except, perhaps, in horizontal cracks, where I quite often place a cam, either on its own or to back up a sideways wire; also a deepening at the back or bottleneck feature in a larger vertical crack (i.e. where one might place a Hex). Oh yes, and certain pockets too .... actually, they're pretty useful on limestone But I'm always deeply suspicious of cam placements in parallel-sided limestone cracks, because I know they can pull straight out, even when they appear perfectly placed.

In reply to GridNorth:

I've taken a number of trad falls, and had gear rip twice - both bits of gear were cams. One I knew was a dodgy (read 'really sh*t') placement, but was pumped and left the cam (backed up by a decent nut a few feet down) in place; the second looked like a good placement, felt like a good placement... but wasn't. I'll always (and did anyway prior to my cams ripping) trust a good nut over a good cam - I suspect like you, that mainly climbing on limestone engenders my preference to nuts.

That said, I've lowered off on micro cams, and fallen on cams on other occasions that have held - I think part of the problem, as has been mentioned already, is that they are often placed when pumped and desperate.

In reply to whenry:

What I do find quite interesting is how a cam, in the presumed perfectly parallel crack, could rip under load but not when tugged. looking at this from a theoretical point of view surely the increase in load on the cam just translates to higher load on the sides of the crack from the lobes and consequently high frictional forces.

In reply to joem:
Are you assuming that the walls are completely hard? What about often dusty rock like limestone? or rock which grains can give on like sandstone?

In reply to joem:

I sometimes wonder if a fall creates some form of whipping motion that, at first, tries to push the cam in which releases some of the outward pressure/friction. I think a cam works with a combination of friction and outward pressure but on limestone, the friction element may be much less.

Al

In reply to CurlyStevo:

The same logic would apply regardless in terms of dustiness and graininess the more load applied the more likely it will hold, think car in snow, mud or gravel.
there are 2 situations where this doesn't apply if the crack is flared or if the placement becomes wider under load due to one or both of the sides moving, a distinct possibility on limestone, the deflection would not need to be that great for a cam to start moving and therefore pop and could possibly leave the rock apparently in tack.

In reply to alasdair19:
"> There seems to be a significant number of accidents when people take a rest and the gear turns out to be inadequate. "

I did that, rested on a nut that fell out the back of the crack.

lesson learned.

In reply to lithos:
"> youtube.com/watch?v=MW1teH6k9xo& "

I wonder if the new DMM dragon lobe design would hold in the situation shown here?

In reply to GridNorth:

I don't seem able to completely trust any trad gear in a fall situation, but would prefer a good nut placement over a cam placement, probably because of the simplicity of being able to see the mechanics in action with a nut.

Regarding cam placements in a horizontal, does it matter if they are placed with the two lobes closest together on the bottom or the top, my gut feeling is it will be more stable with the widest cams on the base, but suspect this makes no difference to holding strength?

In reply to GridNorth:

I do struggle with the logic of some of these types of thread, comparing a good nut placement to a cam in a parallel sided crack.

If it's a good nut placement I'd trust a cam in it. If it's a bad nut placement I might trust a cam in it. If it's a parallel sided crack even a bad cam placement is better than a (unplaceable) nut?

In reply to joem:

I don't buy that.

What if the grains don't become dislodged until a high enough force is applied?

perhaps a similar mechanism could be causing issues with dusty limestone, or perhaps its something else in this case. Anyway I've seen it happen, testing cams by pulling them slowly can often get a different result to a fast hard pull - at limekilns for example.

In reply to irish paul:


Unfortunately that is not necessarily true in my experience.

Al

In reply to irish paul:



I've seen constricting cracks on limestone so polished when I pulled the cam the lobes just retracted and it pulled out the bottom of the crack! So what you are saying doesn't necessarily hold.

In reply to GridNorth:

Spot on Al

In reply to CurlyStevo

So use a bigger cam?

In reply to irish paul:
Don't think you understood what I meant :-/

Short vertical constricting crack (smaller down the way), bottom of crack is open. Right size cam placed. Crack very very polished. Cam just pulls out the bottom of the crack when pulled due to very low friction of side walls.

In reply to BarrySW19:


I've done this quite a few times! I mostly climb limestone, and cams are usually the last thing I'll place, when nothing else will fit.

In reply to CurlyStevo:

No I do, still feel a bigger cam would stick, ie at the point it's acting like a nut

In reply to irish paul:
In this case (a particular climb I did in the Avon / Wye area) no it didn't. The crack was very short and the constriction only a few mm so a bigger cam would not go in. A nut would fit the crack though (although it wouldn't have been good for any side pull)

In reply to irish paul:


In most cases, so would I. But I'd still put a nut in it.

There can be no question that cams have made a huge difference and are a fantastically useful piece of kit. But like any other piece of kit they can fail, particularly in certain types of rock. Well placed in suitable rock, they should be reliable, but intuitively I think passive gear is to be preferred, other things being equal. A nut mechanically jammed into a crack has got to be better than something relying on friction. But in most cases things aren't equal, and a cam may be the best choice.

The biggest problem with cams is that it is so easy to place them badly. It is easy to whack in a cam without giving it too much thought, especially when gripped! Nuts usually require a little more care and attention.

In reply to Howard J:


Tit for tat, the same can be said for nuts. Especially try on rock where the crystals are big or other funky features. Really easy to place nut and get it stuck with only a tiny crystal holding it in place.

It is quite easy to show the outward force of a cam is twice the pull.

However, for small pulls the strength of the springs can be significant, as can little rugosities in the rock which can be crushed out with higher forces. This partially explains the phenomena where a cam stays in for a test but blows at higher loads.

IIRC the assumed coefficient of friction on between the cam lobe and rock is ~0.3 meaning that it will support a sideways load of 0.3 times the perpendicular force. In the case of a cam this force is twice the load but you have a lobe each side so the cam will support ~0.3*2*2 times the pull on it or around 1.2 times the force, so you have something like a 20% margin.

If the rock-cam interface is 20% more "slippery" than this then you've got no margin.

Grippier cams can be made - for instance different materials or different camming angles but this comes at a penalty, weight, durability, range etc.

It is possible to make a lower range grippy cam for specialist applications in slippy rock (eg polished limestone) but I guess no one sees a market for this.

My own experiences of cam failures have always been in crap placements and the cams were always placed somewhat as a last resort.

The only injury I've had was a big cam in a crusty flaring break - the cam held a lot of tests but before moving I gave it one last tug and it failed smacking me in the teeth and nose and nearly causing a nasty fall - I now always lean to one side when testing big gear.

In reply to GridNorth:



Mirrors my recent experience very closely. "Topping out" on Hell Gates on Suspension Bridge Buttress. The climb finishes at a very large bolted abseil station (20mm studding). So I anchored to that, but to get a better position to bring up my second (I did trust the bolt alone, honest) I also placed a large double axel cam (my partner's - I think a DMM Dragon) in an exactly parallel sided crack - the cam was also exactly the right size. Gave it a tug and it was fine. Leant back on the anchors and the cam pulled straight out. Quite a fright.

Martin

In reply to duchessofmalfi:


Go on then..........

In reply to duchessofmalfi:


As far as I can see the ratio is determined by the geometry of the cams (and might vary with the width of the placement). In a symmetrical placement, with the load (pull) shared equally by four cams, I think the reciprocal of four times the ratio needs to be less than the coefficient of friction, so the geometry will be devised to keep this as small as possible......... maybe not small enough for some limestone.

In reply to GridNorth: Most of the gear failures I have seen, both cams and nuts have been a result of poor placement by leaders over their heads on grade, too macho to back off, sticking stuff in and hoping! I try not to climb with them too often. Nothing scarier than watching someone shaking their way up a route as their gear fall out behind them, cams and nuts!
I love passive gear but use cams. I weigh up the placement and use whichever is best. I have been held on most types of rock by both kinds of gear. I rarely have gear falling out.
I got comments from a group nearby when I set of up a route which only required small gear with three large cams on my harness. These were used to hold the small wires down in slots which would take a fall, but where the wire would lift out easily, even when extended.

In reply to Robert Durran:


I think that's right.

And the trade off is between expansion range and holding power. One reason that I use Friends not Camalots.

The early promise was of gear that would be "good" in flared slots! Yet I have seen a perfectly placed #2 friend pull in the beautiful grit crack at the back of Peapod on a greasy day.

In reply to GridNorth:

Personally I attempt to go for redundancy in most situations. That is two ropes, two different bits of gear, ideally a mix of cams and nuts (throw in threads, spike runners and saplings). Of course this is the ideal and sometimes you can only place one bit of gear and that's all you get.

I have found with cams that having the right size is critical, three is no point having a 3 and a 4 but no 3.5 (for example) - you need all the sizes on your rack.

Of course the same thing goes for nuts, but it's rare that people don't have all sizes of nuts. I usually climb with two full sets of nuts (mine and my partners), a set of hexes, a set of offsets, selection of micro-wires, a full set of demon cams and an additional selection of dragons.

In reply to GridNorth:

I've said it before, and (after the barrage of abuse), I'll say it again:

There is no such thing as a bomber cam.

In reply to Fredt:


And it still ain't true...

This one is bomber, no?
https://instagram.com/p/UbdAv-qlBm/

In reply to HeMa:

problem is, the ONLY time you know it's bomber is after you have fallen on it and it has held.

Al

In reply to Fredt:
Hmm well I've taken substantial lobs onto cams and am pretty happy with them generally so I'm going to disagree with that.
Now, my understanding is that 4 cam units walk in, but 3 cams will walk out. So, when I see phrases like 'lifting out' applied to 4 cams, I have to admit to significant doubts as to the original quality of the placement. Is that the case, or have I been mistaken for many years. If you have a cam in a good placement, and it is 4 cam unit that will walk in, what is the mechanism for a cam to lift out?

In reply to wbo:
It depends on the geometry of the crack to some extent but in a parallel sided crack 3 and 4 cam units tend to walk in not out, if you think about how cams grip (ie they push but don't pull out) and then consider what twisting the stem does and where the cam will pivot ite pretty easy to see this.

Any cam can lift out of a flaring or very shallow placement. Also when a cam walks it can move the lobes so they are either not in a good place in the crack or poorly balanced. This could end up with the cam rattling down the crack and falling out (if the crack flares back and down)

In reply to CurloStevo: They don't sound like my definition of 'bomber'. I am struggling to see how a cam can get lift out of a parallel sided, clean crack or break.
For a UK example lets look at horizontal break on Todys wall that I recall as pretty good. Is there anyone here who wouldn't trust a correctly sized, placed cam in that?

In reply to GridNorth:


I once dropped a rucksack full off gear from the top of Bellhagg (gritstone) onto a 2.5 Clog/Vector/Rock & Run cam, which looked fine when placing it (I thought), in that I pulled the cams in and put it in the crack and leg go, and they all contacted the rock, and the rucksack pulled the cam straight out.

I was lying down at the top of the crag, so my view was possibly not the best, but at the time I understood it to be so that if all cams contacted the rock and it resisted a hefty pull, then it was a sound placement.

Reading about rock failing makes me want to go back and check to see if there's any sign of that happening, though it was six years ago. The 'sack was attached to the end of a static sling, and weighed 30/40 lb or something like that.

In a funny sort of way it was quite therapeutic watching my rucksack fall away from me and bounce a little way down the hill side. Worth going out and experimenting to see what happens.

In reply to wbo:
Ive seen it posted on here than cams have quite regularly popped out of the placements on Tody's wall when fallen on (offwidth can perhaps confirm this?)! Probably as the placements have worn and the outer crust has deterioted, once that happens cams are not bomber on grit. My main point was regarding the walking mechanism being very similar not opposite between 3 and 4 lobe cams.

In reply to CurlyStevo:

I wish I had some on this occasion.

https://www.dropbox.com/s/dftjlqtd1n17gp0/First%20Leader%20Fall.jpg?dl=0

Al

In reply to GridNorth: Anything has got to beat looping the rope over a ledge Did it hurt?

In reply to CurlyStevo:

Yes but no serious injuries.

Al

In reply to GridNorth:

On limestone a cam is my last resort.
Off topic, I picked up some discarded limestone from the quarry floor, went home to drill 6mm holes, half the samples fell apart, all looked the same.

Having just aided the majority of The Nose on cams, and only had one pull on me I would say I trust them. The one that pulled when tested was an offset micro cam in a very odd shaped pocket. I did that pitch twice, first time I got the right cam first time, second time it took three or four goes to get something to stick. On both times it seemed miraculous that it held.

On a route in Dovedale a decent sized cam in a shiny parallel sided crack pulled every time I fell on it, which was a few times!

So shiny limestone is at one end of the scale, granite at the other. Would I leave my cams behind, no, a poor cam is better than a nut that falls out, but the trustworthiness of a nut is easier to gauge with certainty. I use ball nuts too, an even more friction reliant device, and have fallen on them. So no easy answers, however nuts are a good starting place to learn, and most learners start on easier grades, which would have been originally climbed on nuts (at most/in general) and so should provide sensible placements.

The answer to the original question......cams are harder to assesse with absolute certainty, but a very necessary piece of kit.

In reply to Robert Durran:

1 / tan-1 13.75 deg ?

In reply to GridNorth:

I decked out on a Severe a few years back thanks to a cam failing. The placement was ok, but it was on limestone. I mostly climb on limestone, so I tend not to trust them. I've taken plenty of falls on nuts and hexes, but all my cam falls, have ended up badly. So I just don't trust them.

In reply to mattrm:


Out of interest why do you still carry them then?

Chris

In reply to GridNorth:

To add some balance to the cam/limestone argument, I did a route a couple of weeks ago at Shorncliff and lowered off a bomber cam. I only got three bits of gear in that I was happy with - two big cams and a hex. They do have their place even on limestone - if it's a textbook cam placement and there's nothing else, you'll have difficulty placing anything other than a cam (or maybe a hex) in it!

In reply to Rick Graham:


Which, as I said, is a property of the geometry of the cam (the angle 13.75 degrees). I hadn't realised that cams are designed with geometry which make this angle (the inclination of the line from the axle to the point of contact with the rock below the horizontal through the axle) remain constant through the camming range.

In reply to HeMa:


Yes, but if that happens you can usually tell. It is usually obvious whether a nut placement is likely to be good or not. Many people just seem to stuff cams into cracks without much thought.

In reply to GridNorth:

Cams can skid out (especially on low friction parallel limestone cracks) but with experience you can tell when you need to be careful and any gear has a chance of failure: your view seems more like superstition than practical sense.

The most famous grit cam placement that sometimes pops out unexpectedly must be the slot at the lip on Flying Buttress Direct, I know of at least 3 occasions that cam has come out in a lead fall and there is talk of others... super polished and often placed a bit blind.

In reply to Howard J:


Same applies for cams. A bomber cam placement is 100% solid as long as the rock stays intact. And you can also see, if the placement is good enough. Just like with nuts, it really isn't rocket science, after all.

So if people just stuff cams in cracks without lookin' it's the same with nuts. Do it blindfolded until something "sticks". So the fault is rarely in the cams, but rather people not even bothering to look for a proper placement... or more likely being too pumped out to even try. Still, the fault is not in the cam nor (the possibly good placement), but rather in the person placing it.

Although I do give you the fact, that cams can be harder to read... after all, they have the adjustable range ie. moving parts. But still, placing solid cams isn't rocket science, and dubious placements are rather easy to spot. Just like with nuts.

In reply to mattrm:


did the cam physically fail, or was the limestone super smooth, flared outwards, the rock moved etc.. when you say failed, there are a huge range of failures?

I happily trust a well placed cam in sound rock.

In reply to Chris Craggs:


I mostly climb in Pembroke/Gower/Wye Valley. On easy limestone routes, I often don't carry cams. When I do carry them, I carry Totem cams which seem to be better.

But on VS/HVS limestone routes, which are my limit, I generally find quickly placed cam might be the difference between having the 'head' to climb though to a good rest or bomber nut. Also they're quite useful as multidirectional runners to prevents nuts from lifting out.

I've not climbed the route in a while, but it was placed behind a flake, on limestone and it was totally behind the flake. No rock failure. Probably a bit flared, obviously a poor placement (otherwise it would have held).

I generally trust cams more on grit or the rougher rock types you get in North Wales or the Lakes.

In reply to Howard J:


Yes, I think that is part of the problem - some people seem to treat them as somehow magical, when one should, whenever possible, inspect the contact of all four cams.

In reply to Robert Durran:


As well as the exact sport and also orientation.

In reply to GridNorth:

I've often joked that cams are faith-based protection. They work if the placement geometry is appropriate, they don't move into a worse spot, the rock surface isn't lubricated (powder or liquid), and the coefficient of friction is adequate. They were designed for granite and are much more reliable there than in limestone, so I think your reservations are totally justified. The only cam designed considering the perspective of limestone climbing is the Totem cam. They seem to be better at all placements, but I have no limestone experience with them to make even anecdotal judgements.

The idea that a good nut placement is a good cam placement strikes me as way off. I see the two types of gear as more complementary than overlapping. Cams are best in parallel-sided placements, nuts require constrictions. A cam placed in a constriction can walk to the wider part and "umbrella." The more pronounced the constriction, the more likely the cam will walk to a position of uselessness. I suspect that a lot of unanticipated cam failures in good rock are because the cam was placed in a spot with appropriate lobe compression but subsequently moved. You can't just look at the spot the cam is in, you have to ask whether it might move and if so where it could end up.

If parallel-sided cracks are not in the offing, then a cam placement requires the same kind of attention as a nut placement, even though it doesn't often get it. You have to eyeball the placement and see what the cams are doing and what they will be doing if the cam moves a little. With the smaller cam sizes, there is almost no room for error and the idea of "range" is really wrong-headed. You've got a piece that will reliably go in essentially only one width placement, and that's with the lobes nearly fully compressed. Any compression less than that and a tiny movement will spring one or more lobes and leave you with crap pro.

In reply to rgold:


.........and the risk that it becomes overcammed and you lose it!

In reply to rgold:

Excellent informative post (as usual)

Would just like to add that placements are usually optimal when all the cam lobes are equally compressed.

If the cam has moved slightly or the load is not in the exact direction as placed, the cam lobes will try to adjust and may then be offset. All your pretty triangle of forces/ friction resulting from ( 1 / tan-1 13.75 deg) outward forces then get very complicated. In knobbly/ low friction limestone the cam often loses out , far more margin in a granite placement (usually).

Against the instructions I normally bottom cams out if possible ( like at the back of a pocket ) so it cannot reset.

In reply to Rick Graham:





I think the problem is that a cam that is out further than the others may not get loaded or may only get a little of the load, leaving more for the other cams to do. One of several significant advantages of Totem cams is that each cam is directly individually loaded and so the cams can be "offset" and still all function properly.

In reply to GridNorth:

Cams in good breaks on grit as are good as bolts, or better - fallen on them bags of time, never had one rip. Grit was made for cams...

Don't really like them in vertical cracks on limestone though - not fallen on any and don't intend to. That said, I've had and seen wire placements that seemed good rip on limestone too, so I'm generally more circumspect, especially on the shitty Peak choss (although Chee Tor is the exception with its brilliant seemingly custom-made wire slots).

In reply to rgold: Sorry, I don't get that - surely the point of the constant angle cam is that one can be extended more than that others and the forces will remain the same. Otherwise the logical extension of what you say is that holding power would vary with the extent of contraction. Remember also that while the totem lobes might be individully loaded they still need something to 'push' against

One thing I am curious on, is that for some of these placements where cams are sliding out, if a sudden large force (a fall) would be held as the cam starts to work 'properly'. Is the answer to sliding to increase the low force friction of the cam lobes? Skateboard decktape?

I think there is confusion seeping in here re: placements with different lobe compression...

It doesn't matter if the lobes are differently compressed _but_ most placements where the lobes are differently compressed tend to be a dodgy because the reason the lobes are differently compressed is the placement is flaring along the axis of the axles.

If the flaring results in radically different compression then the cam may skid sideways or walk out under loading or waggling or walk in and jam.

Under these conditions you can also get the axle(s) asymmetrically placed in the crack which tends to leave one lobe under cammed while the opposite lobe is overcammed and I've seen this result in the lobe flipping over and looking simultaneously useless for protection and incredibly difficult to get out without damaging the cam.

It is possible to imagine a stepped placement with perfect parallel sides but lobes compressed by different amounts either side of the step - assuming the placement is symmetric the lobes will be perfect on both sides but with different compression.

So: differently compressed lobes are ok in principle, however, placements causing differently are often sub optimal in practice or something like that!

In reply to wbo:

As for increasing the friction with say, skateboard decktape: the problem is the forces on the lobe are quite high and the areas of contact quite low so the surface has to withstand a lot of pressure so what ever it is probably has to be tougher than a this (back of the envelope estimates suggests >1000 times the pressure comparing cam lobe with skater's shoe).

The tooling found on cam edges is only partially functional - the main reason it is there is most people wouldn't trust a cam without "tread".

Changing the metal or alloy is one thing that can be done but I'm pretty sure this is already done and the practical choice is limited to a few sorts of aluminium alloy in practice. There maybe other materials but engineering costs of making a "tire" or the material cost or weight penalty for these are probably quite high.

In reply to GridNorth:

There are inherent problems with cams in much the same way there are inherent problems with nuts - if you don't place them properly in the first place, there's always the possibility they'll rip.

Unfortunately, as others have said, a lot of people think a cam has magical properties and can be just lobbed into any placement and it will hold, which of course isn't the case - limestone being the most obvious example.

Personally, I have a slight mistrust of cams and will always look for a good nut placement first - unless climbing on granite, where cams work best - and only tend to use cams when I can't find a good nut placement.

In reply to GridNorth:

This isn't "either - or", cams vs nuts. Both are reliable, up to a point. Both can rip. Both depend on being placed correctly, and on factors like rock type and strength, direction of pull, etc.

The point with cams is that the user needs to understand how they work, and the factors which may cause them not to work. It is fairly obvious simply from watching other climbers at popular crags that quite a lot of people don't fully understand this. You also see a few who seem to think that cams have made other gear obsolete and who use them as their first choice, rather than choosing the most appropriate gear in that situation.

I use cams, I've fallen onto cams. On the whole I trust them, as much as I trust any gear, especially on grit but less so on limestone. For preference I'll choose passive gear, especially for belays, but if a cam is the better choice then I'll happily use that. Obviously there are placements where a cam is the only choice.

In reply to Robert Durran:


Which is why I find myself fiddling with them even on granite if the granite has large crystals (e.g. Dartmoor) - such cracks are usually not very consistent on cm scales and small movements of the cam can change it from all four lobes balanced happily to one lobe totally wrong. Perhaps I worry too much...

In reply to andrewmcleod:


Nope, in big crystal rock, like Sennen or Dartmoor... It's quite wise to fiddle the cam around, until you're happy about the placement. So exactly the same as with nuts.

In reply to HeMa:


Good point. We shouldn't generalise about granite. I've just been in Cornwall and found satisfactory cam placements decidedly problematical in the crystalline rock - even nuts needed extra care. Totally unlike the superior versions of granite such as in the Cairngorms or Chamonix

In reply to GridNorth:

Once took a 15 metre fall and the only pro that did not rip out was a cam in horizontal break on limestone. Horses for courses

In reply to neilh:

The other year I held a 15 metre fall where all the cams ripped good old hexes

In reply to Rick Graham:

Lol.......

In reply to neilh:

And for balance, I have also held a 40m fall where only a cam stayed in

In reply to GridNorth:

When I seen Arnaud Petit climbing Black Bean in Ceüse he placed loads of cams. My heart was in my mouth.

http://www.ukclimbing.com/articles/page.php?id=4079