Retiring dropped gear

This is a hypothetical question for everyone:

What would you do if, say, you're climbing in the Gunks and your blue metolius mastercam (number 1) and the blue neutrino it was attached to just jump out of your hand and go spinning through the air to the ground below. Let's pretend it fell about 200 feet, went through some tree branches (though sparse enough to be very unlikely to slow it down) and definitely did not bounce off the cliff at any point. After rapping, you find your cam and biner lying in the dirt (though there is no way to be sure it didn't bounce off a rock before coming to rest in the dirt).
Aside from scratches and scuffs much like any used gear, there is no visible damage, everything is intact, trigger operation is smooth. Do you:
A. retire cam and biner immediately
B. return cam and biner to your rack and assume they are as trustworthy as any other piece of gear
C. return cam to rack, but never quite trust it - i.e. don't place it to protect a crux, before or after a long runout, or really ever if you can get a different piece in.
D. other?

If this was your gear, what would you do?

Disclaimer: this is of course entirely hypothetical, and even if it wasn't, noone will be held responsible for their advice. I will in the end make my own judgment call and be responsible for the consequences of said judgment call. Or I would, if I had done anything so stupid as throw my cam off a cliff.

sell it on ebay

E. Read the many pages on expert info on the Internet about the myth of microfractures and therefore the relative robustness of dropped gear. Then promptly put the piece in question back on the rack.

if the lobes work, and the axle isnt bent, and nothing looks trashed on it i would just put it back on my rack

D return cam and biner to your rack and know they are as trustworthy as any other piece of gear

Clyde wrote:D return cam and biner to your rack and know they are as trustworthy as any other piece of gear

+1

Buy another one. . . get rid of the old one.
How cheap is your life ?????

The "danger" of dropped gear has been discredited as myth.

If it looks and works fine, its fine.

I would think that the forces of it impacting the ground are far less than those placed on it during a good lead fall. Imagine someone throwing it off the cliff and you catching it, I bet it wouldn't hurt too badly.

• **Edit-I'm no physics person, so I might have screwed up, but I ran this scenario through a impact force calculator and it said that a blue met cam hitting the ground would generate an impact force of 0.354KN. Cams are rated to how many KN? Granted the forces are applied differently than in a fall, but still...

Numbers used:
weight of cam: 54 gms
distance fallen: 67m***

Evan

test it. fall on it with a backup piece or bolt and see what happens. a #1 metolius isn't even heavy enough to do any damage to itself from a fall...

Yeah, test it. Plug it somewhere low and jump on that sucker in a static sling. That usually eases my mind.

• *Disclaimer: I agree with the other posters, its probably fine. However, as far as the physics is concerned... **

Evan1984 wrote: ***Edit-I'm no physics person, so I might have screwed up, but I ran this scenario through a impact force calculator and it said that a blue met cam hitting the ground would generate an impact force of 0.354KN. Cams are rated to how many KN? Granted the forces are applied differently than in a fall, but still... Numbers used: weight of cam: 54 gms distance fallen: 67m*** Evan

What calculator? A "climbing" fall calculator can't really do this calculation... the main variable that decides the peak force felt during a collision is the distance over which the object can slow down.

For the falling cam striking, in the worst case, a solid piece of granite, we can basically assume that the granite does not bend or budge more than a few angstroms (this is 10^-10 meters, roughly atomic scale). Aluminum will dent and bend, though. Let's take the simplified scenario where the cam just hits the rock with the lobes down and takes all the impact on the aluminum. The aluminum doesn't bend much, but it will deform a little. Say it dents 0.1 millimeter:

Mass: 54 g
Height: 67 m
Deceleration Distance: 0.1 mm
Average Force during collision: 354 kN

The calculator used to do this is located here: hyperphysics.phy-astr.gsu.e…, and makes a bunch of simplifications, but its unimportant. Point is that collisions between hard objects have enormous instantaneous forces.

Anyways, like I said before, I really don't think any of this matters as far as the cam is concerned, except I wouldn't go with C. If you don't trust it, get rid of it.

Chris

Chris Drover wrote:**Disclaimer: I agree with the other posters, its probably fine. However, as far as the physics is concerned... ** What calculator? A "climbing" fall calculator can't really do this calculation... the main variable that decides the peak force felt during a collision is the distance over which the object can slow down. For the falling cam striking, in the worst case, a solid piece of granite, we can basically assume that the granite does not bend or budge more than a few angstroms (this is 10^-10 meters, roughly atomic scale). Aluminum will dent and bend, though. Let's take the simplified scenario where the cam just hits the rock with the lobes down and takes all the impact on the aluminum. The aluminum doesn't bend much, but it will deform a little. Say it dents 1 millimeter: Mass: 54 g Height: 67 m Deceleration Distance: 1 mm Average Force during collision: 300 kN The calculator used to do this is located here: hyperphysics.phy-astr.gsu.e…, and makes a bunch of simplifications, but its unimportant. Point is that collisions between hard objects have enormous instantaneous forces. Anyways, like I said before, I really don't think any of this matters as far as the cam is concerned, except I wouldn't go with C. If you don't trust it, get rid of it. Chris

That's the calculator I used. I entered:

0.054kg mass
67m height

I let the calculator enter the constants and got 354.???NEWTONS, which is equal to .354KN. NO?

What am I doing wrong?

I understand the instantaneous forces idea, but it was also said that it would be striking branches on the way down, so for this simplified experiment, I allowed the stopping distance to be .1m, which is the shortest the calculator was letting me enter.

Evan

Evan1984 wrote: That's the calculator I used. I entered: 0.054kg mass 67m height I let the calculator enter the constants and got 354.???NEWTONS, which is equal to .354KN. NO? What am I doing wrong? I understand the instantaneous forces idea, but it was also said that it would be striking branches on the way down, so for this simplified experiment, I allowed the stopping distance to be .1m, which is the shortest the calculator was letting me enter. Evan

I'm honestly not sure exactly what I entered, since I've been unable to exactly replicate it - I ran a bunch of calculations and probably did a lot of rounding. I also made a typo above - fixed now - should have been a 0.1 mm dent (you would EASILY see the damage from a 1 mm dent). Fail for me.

Point was there's a big difference between 0.1 m stopping distance and 0.0001 m - average force is 1000 times higher. Odd that it wouldn't let you enter a smaller number; my browser didn't give me any trouble.

As far as the tree branches, I just ignored them, since generally in the stopping distance you are referring to the collision itself.

All largely irrelevant, anyways, I just try to make myself feel like four years and shitload of money for a degree in physics and chemistry was even remotely worth it. =)

-Chris

Evan1984 wrote: That's the calculator I used. I entered: 0.054kg mass 67m height I let the calculator enter the constants and got 354.???NEWTONS, which is equal to .354KN. NO? What am I doing wrong? I understand the instantaneous forces idea, but it was also said that it would be striking branches on the way down, so for this simplified experiment, I allowed the stopping distance to be .1m, which is the shortest the calculator was letting me enter. Evan

stopping distance of 0.1 m would be crazy long. that would mean the cam penetrated 10 cm into the rock! i'm not having any trouble changing the stopping distance.. i put in 0.005m (5 mm) and got 19.6 kN from 40m height and 49 kN from 100m height

LOL, I find it kind of funny that you say it's just 'hypothetical'. Pretty descriptive hypothetical scenario... I know you don't want to put yourself or partners (potential partners) in a position of questioning your gear.

Another option is to have the piece(s) magnaflux tested, and bounce testing like an aid placement perhaps could be of peace of mind. Or if you're really questioning the integrity of the piece, just replace it.

Juan

Hypothetically, the annual Spring Gear Swap at R&S is in 4 weeks. Sell it there.

If everything is unscathed, answer B, all the way. But if YOU have doubts, take it the pieces out and bounce test them. If, after that, you still have doubts, retire them.

Know someone that works in customs at the x-ray machine? A dentist perhaps? Their machines can see microfractures... they stick out like a babboon's penish!

Gunkiemike wrote:Hypothetically, the annual Spring Gear Swap at R&S is in 4 weeks. Sell it there.

That is the d-bag thing to do... on par with selling a car that may or may not have a time bomb in it.

Phil Lauffen wrote: That is the d-bag thing to do... on par with selling a car that may or may not have a time bomb in it.

+1 d-bag counter.

good friends w/ a cam maker and the urban legend of internal stress fractures in aluminum is just that: mythical. if the metal is in tact than it is still good, aluminum doesn't fracture internally without showing it through the entire cylinder