UKH

A general musing I suppose. So I was revisiting calculations today from a while back, and specifically how close you can get to the range of a double axle cam with a single axle. It turns out it’s about 1 percent less if you use a slightly higher cam angle and optimise the trigger pull points. I went through the calcs several times to make sure. So my question is, if this is the case and we are eliminating range as a reason for choosing double axles over a single axle unit, is there still a case for single axle cams in the premium market and if so, what are the for and against arguments. I know what I think, but I’m curious as to the market perception... answers on a postcard?

In reply to beardy mike:

I have a full set of Totems (single axle) paired with a set of Camalots.  It may be that the Camalots have a greater range, but it isn't noticeable to me in any practical way.  Plus, I find the very thin border on the smaller double axle cams (created by the slot need to accommodate the other axle from the one the cam is mounted on) to be worrisome; there just isn't much metal there...

In reply to rgold:

pretty much identical setup

Totems (green down to black) and C4's

Despite the slightly larger range of the C4, the Totems fit in more placements more securely than the C4, if I'm only carrying a single set of cams it will be the Totems.

I think the strict answer to the OP is the single axle is the way to go 

For gear designers, the next generation cam has to beat the Totem

'Thin metal on cam lobes' - only just spotted this issue, might replace small grey and blue C4 eventually

In reply to beardy mike:. Mike - a point of clarification - is there anything you needed to compromise in the design of the single axle cam to get the extra range? 

Not a criticism, just want to know if we're in  a situation of 'you can have extra range but X is reduced'

In reply to beardy mike:

Yes, because they are lighter. 

In reply to wbo:

That was my first thought too - does changing the cam angle have any effect on holding strength?

If not, then I don't see any reason it wouldn't be successful. Climbers aren't daft, and they're pretty ready to accept innovation in gear. If it could be demonstrated that the new design was just as strong as a Camelot/Dragon/etc, had basically the same range, but came in lighter, I think they'd sell perfectly well.

In reply to beardy mike:

How much higher? A number of manufacturers have been banging on for years about how their camming angle is just perfect, and could be quick to jump on a competitor with a higher angle shouting "Less holding power!!".  And if you can win the marketing war (perhaps with good metallurgy and some stickier cam surfaces) will the same camming angle on a double axle cam get them the range advantage back?

Not aiming to criticise, just musing...

In reply to John Kelly:

The reason for the cut away is to make the head width narrower and to allow the trigger wires to operate as they should. There is a practical reason.

As I'm not getting many responses I'll add a little more detail.

Typically the issues with single axle cams have been cited as:

• Less range
• The heads are floppy and can invert making them difficult to retrieve from cracks.
• They can overcam more easily than a double axle cam.
• Less curve appeal

Double axle cams though are:

• Inherently heavier
• less stable in placements - double axle cams allow the cams to move independently of one another as the stem moves back and forth.
• often have lower spring strength which is critical to the initial holding power of the cam as load increases at the start of a fall.
• Small sizes in suboptimal shallow placements can tend to crack the lobes when loaded. Certainly below the 0.5 size this becomes an issue.

In reply to wbo:

Yes, sligtly - the camming angle is a higher angle. It's still less than camalots and aliens though, so with a srong spring tension and a grippy surface I don't see why you'd not be able to make something very workable.

In reply to Jack B:

The reality is it is very difficult to do comparitive tests in a real world scenario. You might be able to get a general feeling, but the trouble is rock surfaces are massively variable and unhomogeneous. Even using the same jig and same rock would not necessarily work as your placement would be on a slightly different patch of rock etc, so very difficult to gain a meaningful comparison. So the marketeers kind of do their stuff. The reality (or my reality atleast) is that camalots seem to work just fine and they are at 15 degrees, aliens are reknowned for sticking and they are at 16ish.

In reply to beardy mike:

My question would be: if car wheels grip better on road (a rock-like surface) when covered in rubber, why wouldn't a cam behave likewise if it had tiny cam tyres on? That way the cam angle could be adapted accordingly to give the same holding power but considerably greater range?

In reply to beardy mike:

Fair point.

That's never really been a problem for me.

Again, yes, in principle this can happen, but it's never really been a problem for me.

??

In reply to john arran:

I struggle to see a thin layer of rubber surviving long whilst being pressed with mulitple-kilonewton force between a narrow metal blade and a rock. 

In reply to beardy mike:

I can't imagine the spring strength contributing anything significant to the holding power.

[Reasoning: transverse forces exerted by a cam (@13 degrees camming angle) are pretty much twice the pull on the stem. Just assume climber sitting hanging, held by the belayer.  The weight is 80Kg so the force is ~1.6kN (160Kg).  Assuming the springs must be retractable by one finger (which limits the force the spring can exert) the force the spring loading of the cam will exert will be trivial compared with the 1.6kN required to hold a static climber and will be negligible considering the force required to hold a big lob. ]

The camming angle is set so that the outward force multiplied by the coefficient of friction exceeds the pull for each side of the cam.  The typical values for the coefficient of friction between aluminium and stone varies between 0.3 and 0.4 depending on the stone/metal mix.  For a typical cam with 13 degree camming angle the holding power varies between 1.2 and 1.6 times the pull (4*0.3 to 4*0.4). 

It is known that cams do skid out of slippery polished limestone cracks so there are circumstances where the holding power must be less than 1 and you'd like a lower camming angle here (to increase the outward force and enhance the friction) but this particular situation is very had to reproduce because the surface condition is important and hard to define.

I think the exception to this are totems because the pull is exerted away from the axle which imposes a torque on the cam exerting additional outward force - the cam lobes are also obviously not an exponential spiral but I'm not sure what the shape is where it matters and haven't done the maths to analyse the holding power.

In reply to AlanLittle:

This is correct - the rubber doesn't survive the pressures exerted.  However a cam with "fat tyres" would work in this respect but my feeling is would not be practical because the rock surfaces in practical placements are rare flat enough for a fat tyre to sit properly, I've not done the analysis but I reckon the weight of a sufficiently fat tyre would put most people off.

In reply to gravy:

Not when it's loaded, no.  However, when unloaded, it's only the force of the springs (and its own weight) holding it against the rock and thus causing the friction. 

In a fall, the cam will then transition from the unloaded to the loaded state, but that will take time, and it does seem probable that the spring strength affects how/whether that happens, as opposed to the cam just coming out. There has to be some combination of placement flare and rock smoothness where the spring strength would be critical. 

In reply to gravy:

What I'm talking about is the initial stages of a loading, the milliseconds as the load comes onto the placement. If the spring is strong, it is more likely to apply enough lateral force to prevent the cam from skidding out o the placement. This is not the theoretical but the practical application of the system. It is where totems strength lies to some extent because the load force is actively increasing the lateral force by rotating the cams into the rock.

In reply to john arran:

It has actually been tried. My feeling has always been that the rubber would just deflect and allow the cam to skid in practice, abit like putting the brakes on in a car with no ABS - the tyre cannot bear the load and just bends out of the way, thereby ripping the rubber.

In reply to john arran:

As others have said, presumably rubber would not last.

But one could think of adding "shoes" of very soft metal to the cam lobes.   The Aliens had rather soft metal to increase holding power, which works in small sizes. I gather that larger cam sizes don't use soft metal because it would not be structurally strong enough.  But a cam lobe of harder metal with soft-metal shoes might be good, though presumably hard to make. 

In reply to Coel Hellier:

Well precisely - adding a soft layer to a hard lobe is just super difficult to do without adding cost and complexity to the manufacturing process. I have an idea for that but it's a long way down the road...

In reply to beardy mike:

I did a project with somebody working the other way round, making the lobes grip into the rock better using bonded tungsten carbide (the end project was possibly going to be industrial diamonds). One look at the damage it did to the rock put that idea in the bin!

In reply to beardy mike:

I suppose its range Vs weight Vs holding.

I'm not sure what a 1% sub-optimisation of each if those means in reality nor what the impact on the others is.

If you're offering a material weight reduction for only 1% reduction in holding power then I'm in. If it's 10% then I'm not.

In reply to beardy mike:

I suppose the counter is if you then take the same slightly higher angle and optimised trigger points and apply them to double axle what do you get...

In reply to Deadeye:

You more or less get a camalot c4, the angle is 15 degs, but the difference is that with a camalot the motion of each lobe is restricted by the second axle, with the result that each lobe can only rotate through 90 degrees as opposed to 110 degrees. The extra 20 degrees of rotation is where the increased range comes from. The only thing you then need is the ability to the cams as far as you need to - in the past they've just been slapped on any old how which kind of worked to start with. But it's really not that difficult to achieve if you know what you are looking for...

In reply to beardy mike:

I'm certainly no materials scientist but surely the ideal would be a surface material that was softer than the metal of the cam but has a degree of elasticity (as opposed to the permanent deformation of softer metal). It may need to be a particularly dense rubber but surely there is a compromise waiting to be found.

In reply to john arran:

Sure - it's the manufacturing process which is the barrier - it was all being researched and then all of a sudden it wasn't anymore...

In reply to beardy mike:

Could some shape memory effect (superelastic) alloys be useful there? Or would that be useless for that purpose? I am no engineer, so excuse me if I am totally off 

Of course I can understand that the engineering hurdles (and price!) would be pretty high...

In reply to beardy mike:

I wonder if the rock bearing surface layer could be selectively annealed with controlled localised heating process leaving a shallow heat affected zone, perhaps using something like a laser or ion beam welder or more crudely perhaps even just quickly rolling against another very hot surface. I suppose they'll harden eventually with age and before they do the downside is more wear and tear, flat spots, pitting and smeared metal from falls. Anyway, cams as we know them made from pretty hard aluminium work well, I suppose you're looking more for easily marketable 'gains' like weight or head width than a collection of subtle ones which add up to little but more cost.

I've never had much of an ideological preference either way for single or double axle, there are minor pros and cons but the bigger differences always lay in the details that vary across manufacturers and time: triggers, slings, stem durability, jamming susceptibility, weight, cost...

jk

In reply to beardy mike:

I've always liked my current combination of Flexi Friends up to size 1 and Camalots above that.  The uncluttered simplicity of the smaller Friends is pretty appealing and carrying more units is not so much of a problem in these sizes.   When I first got Camalots I was always impressed by the spring effectiveness on the larger cams compared with Friends etc. and have stuck with them.

In reply to beardy mike:

It seems that double axles are popular on bigger cams, but single axles are popular for small to micro cams.

Most people just want cams that seem/feel/promise to be bomber. I can't really see the appeal of totems, for example - they're really expensive and don't rack well. But, they pretty much create a fear and then promise to solve it, with all their talk of independently loading lobes. People go for that.

You wanna sell single axle cams? Then go around telling everyone that double axle cams are prone to catastrophic failure if you take a big whipper, and that only the tried and trusted Jardine design will keep them from decking out. Suddenly people will be giving their C4s away...

Well... maybe!

In reply to C Witter:

"Totems ...and don't rack well. "

Only people who don't own them seem to feel that way.

In reply to C Witter:

This is news to me.

In reply to DubyaJamesDubya:

You may be on to something there! If I'd spent £70 on a cam, I'm sure I'd find it far superior to any others.

In reply to C Witter:

Being an early adopter I paid less than Camalots and only very slightly more than Dragons (which I also have) were going for.

In reply to C Witter:

There you go, Beardy Mike - the dislikes of my mere suggestion that Totems aren't all they're cracked up to be just goes to show how powerful spinning out a USP is to creating a devotee fanbase for your new cams. Maybe design a 5 lobe cam, just to shake up the market.

In reply to C Witter:

Or maybe people just like them because they're a good cam. I don't personally like Camalots, but it doesn't mean I go around telling everyone who has a rack of them that they're a victim of marketing.

In reply to C Witter:

Wow! People disagree with you and they are gullible fools.

In reply to C Witter:

I don't think anyone "goes for" independently-loading lobes.  Almost everyone I know started out skeptical and changed their mind after actually using Totems.  No one said, "wow, I love how those lobes load independently!"

Racking is no problem.  If it was, Yosemite big-wall climbers wouldn't  be using them, and they are.  I typically climb with a single set  of Totems combined with a single set of Camalots and I've never experienced the slightest inconvenience.

The independent loading of the lobes is the most esoteric feature of Totems.  The claim is that they have greater holding power, but I don't know of any testing to confirm that.  However, if you have to place cams in flared placements, you'll find that Totems eliminate the need for offset cams maybe 50% of the time, because of the way the lobes engage.  In those situations, the Camalots bounce-test out and the Totems hold. This has been observed over and over.

The combination of the super flexible stem and a very small amount of play in the head seems to make Totems walk less than other cams.  And the flattened top shape of the lobes makes Totems noticeably less likely to get so overcammed they're stuck.

But the main day-to-day advantage of the Totems is their narrow head width.  (For example, the purple Totem has head the width of three of the four cams on the same-sized purple Camalot.)  Not much of a deal if you are climbing parallel splitters, but in featured rock the head width is a game-changer, because the Totems fit where other cams do not, and a cam that won't fit into a placement is of course utterly useless.

If my Camalot fits, I always use it first and save the Totem for a narrow placement if one shows up.

In reply to C Witter:

I've started with two Totems, red and green, 'just to see what they're like' - I now have a full set of them.

Trust me, if they hadn't impressed me that much, I wouldn't have bought more (I already had a set of Camalots 0.3 to 3). I don't know what it is, but they just seem to stick a lot better than any other cam I've placed before (Camalots, Dragons and Friends).

They don't rack well? What the hell are you on about? They take less space on my harness than my Camalots (granted, the biggest Camalot I have is bigger than the biggest Totem, but they still win even if we only compare the matching sizes)

I won't be getting rid of my Camalots yet as I find the size overlap between them and Totems useful, but maybe try some Totems before accusing all of us of being gullible fools?

In reply to DubyaJamesDubya:

I don't think I used the term 'gullible fools', to be fair... I was just enjoying a lighthearted troll

You've convinced me. Where do I sign up?!

In reply to C Witter:

Suggesting that people are buying something because it is marketed well and 'because it is too expensive', even though it isn't any good, implies gullibility.

So far as I can tell the take up of Totem cams has been driven solely by positive feedback from actual users.

In reply to DubyaJamesDubya:

Phew...! Thank God we got that settled. Well done.

In reply to C Witter:

You're welcome

In reply to DubyaJamesDubya & CWitter:

Alright alright kids - enough of the playground

So I went to the Outdoor show in Munich, and there I was able to play with them all. Interestingly the X4 and C3 are being discontinued and being replaced with a cam called the Z4. I had heard this was to be the case and had assumed this meant they would continue using the X4 head in a modified version - IMO it was a great piece of lateral thinking if of limited practical use. But actually the Z4 is a straight up single axle cam. Seems like BD making an admission that in small sizes the extra range is of limited use and appeal. 

It also looks like the Totem Basic is off the market at the moment. So I got to touch up a Totem Totem, fixe aliens, the dragonfly, Dragon, C4 in the new version, The ul C4 and all the metolius cams including the super cam, and lastly the OP Link cam. I was really impressed with the Dragonfly - for me this is now the microcam to beat - everything you’d expect from DMM. Aliens, somehow, just aren’t that smooth or nice. I’m sure they are fine but DMM smashes them. The Z4 - well I was totally underwhelmed. They have a new trigger system which makes the stem  more rigid when you pull the trigger. To me it looks fragile and actually I don’t find the stem bending an issue on any of the others. A solution looking for a problem as far as I can see. No camstops on the small ones... I know WC have their microcam on the way too. Some elements which I suggested to them a while back which we all decided were not so nice, but seem to have resurfaced... I guess we will see. And totem totems - just still totally meh for me... 

In reply to beardy mike:

Whats meh about them? 

Have you actually used a set?

I’ve had my set for six years and have used them for loads of trad, and a bit of big walling. I match them with a set of Camalots most of the time.

They fit in places where other cams don’t. Due to the narrow head width you don’t really need offset cams, and they work great in pin scars.

They inspire confidence in marginal flared placement and on slick rock like limestone, where in my experience conventional cams can skate out.

Sure they look a bit funny, but who really cares...

Also the racking is a total non issue. The only people who carp on about it, are folk who don’t own them. 

Tom

In reply to Tom Ripley Mountain Guide:

Don't really know Tom - I haven't particularly got an issue with them, just can't say I struggle to find placements which are secure with standard cams. I'm sure if I was a demon and climbing really hard stuff that was difficult to protect then I might have a different opinion, but I don't... and by the way, I mainly climb on limestone, and I never find my placements skate out. I remember when I first tried Helium friends they did a couple of times but they have a weird round cam surface from being forged... but once they wore a little bit, they were fine...

In reply to beardy mike:

Have you used them?

In reply to Tom Ripley Mountain Guide:

No, I've not had a chance. As I say, it's not a meh feeling based on anything in particular. I'm sure in specialist placements they would rock my world, it's just that I don't come across those placements that often... maybe I don't know that I do come across them and I'm living in an echo chamber of my own creation... You'll note I've not slagged them off like others, just expressing a relative indifference....

In reply to beardy mike:

Don't you start, Mike! I didn't slag owt off, if you read back through the whole tedious exchange: I didn't say they were crap, just that they're expensive and my impression was they would be awkward to rack. In other words, just teasing people's emotional/subjective relationship to their gear - what seems/feels bomber, what doesn't; the way we latch on to little quirks, as though they make all the difference (e.g. I've started racking my nuts on different coloured carabiners - andI swear, I've jumped a whole grade since...! ). But, some people take themselves very seriously, so I guess the lesson for me is not to pull people's legs or they'll start accusing you of all sorts!