UKC

I noticed the other day that one of the lobes on my 0.75 Camalot wasn't opening fully - turns out this is because the metal has got mashed (see photos). Just out of curiosity, would anyone like to speculate on how this has happened? Because it's not just a single smooth deformation of the metal I'm inclined to think it's not an interaction between the axle and the cam lobe when under-cammed. Perhaps grinding on a very unluckily-placed rock edge that was forced into it while heavily cammed (and therefore that part of the cam was accessible)? I'm not in the habit of taking big falls, preferring to weight gear where possible (and preferring not to have to do that, of course!) but it's been known to happen. I've no idea how long it has been like this, probably some time since my gear doesn't get that much mileage these days and I haven't fallen on this piece recently

Can't help re mechanism but I have managed to put dents and similar lumpy bits on a cam lobe after a protracted battle to remove one with 2 nut keys. I was teasing each lobe out out of the crack by pulling the holes in the lobe with the nut key. The metal the lobes are made of is pretty soft and does not need much force to deform them. 

I sorted mine by sanding the sharp bits down. I used it for years after the incident with out issue.

Really? That's interesting. I wouldn't have imagined the metal to be soft enough to be deformable just by bashing/tugging with a nut key!

I've actually just noticed that the affected cam lobe also sits a bit skew (even when the mashed part is away from the axles) and the stem is off-centre. It's possible the stem position is only set by the metal springs, I'm not sure about that, and the lobe tilt could be a consequence of that. But overall, since I'm in the position of being able to afford a replacement, I'm inclined to retire this one. The last thing I want is to be gibbering on a run-out and wondering if my last piece was this green cam...

Levered out with a nut key by the looks.

I'll third vote for a nut key causing the "nicks". Having just recovered a overcammed unit, and filed all the burrs off it.

Does the cam lobe wobble on the axle? or has the cam lobe been bent? or the axle?

There's the dent in the lobe, it got a lot of tugging to free it.  

If it wasn't a nut key it could have been caused by an ice axe if someone has bashed it to remove it when winter climbing 

di cam got mash up wi di nut key

See, that's the sort of thing I would have expected to be needed to put that much of a dent in it, but I don't winter climb these days and the cam's definitely never seen snow. Based on what everyone's saying, I suppose they're just softer than I'd imagined.

The lobe wobbles a tiny bit, but that could just be because the springs have shifted slightly - the other one can be compressed against the springs if I push hard, which I think is normal. The cam lobe might be ever so slightly bent, but not significantly. If I put a straight edge against it I can't see any bend; if I look at it my eye says it's slightly bent, but it's hard to be sure with the various different radiused curves on it. The axle is straight, as far as I can see.

Lobe(s) wobbling slightly is normal, a lot is time to scrap.

The Aluminium lobe will always lose to the Steel axel, made worse by crevice corrosion -> metal in a crack corrodes faster than an open surface.

All my scrapped cams became too "wobbly" to use for my state of mind.

It could have got a bit of loose rock stuck between the cam and the axle/end plate perhaps? Is the inside of the end plate damaged?

End plate seems ok as far as I can see. Looking more closely with careful spotlight illumination, there is matching (and narrower) scoring on the hidden far side of the lobe. I'm sure people are right about it being damage from a nut key. You live and learn...