Mountain Project Logo

This is safe, right?


Original Post
Lou Cerutti · · Carlsbad, California · Joined Jan 2014 · Points: 217

Spotted this on someone's rack in jtree and had to snap a pic. #1 C4 with a hair pin for trigger wire. Seems legit..

C4 Hair pin trigger wire
Rich zz · · california · Joined Oct 2012 · Points: 180

If it's stupid and it works then it's not stupid

slk · · Reno, NV · Joined Jan 2011 · Points: 150

Looks good from here.

Locker · · Yucca Valley, CA · Joined Oct 2002 · Points: 2,265

Looks like a successful quick fix.

Curious as to why you're questioning it's safety?

Eric Klammer · · Boulder, CO · Joined Oct 2012 · Points: 2,075

You are correct, this is safe.

Lou Cerutti · · Carlsbad, California · Joined Jan 2014 · Points: 217

To be honest I just found it entertaining and thought I'd share. The lobe did look a little tweaked though.

csproul · · Davis, CA · Joined Dec 2009 · Points: 330

If the wire is preventing/interfering with the cam lobe from expanding, ie holding it closed then no, I don't think it is safe. Unless it is only placed in cracks that cause it to be cammed well past the point where the trigger wire is holding it closed.

In and of itself, the hairpin is fine for a quick fix, it only needs to allow the cam to be retracted so it can be cleaned. But if it starts to interfere with the ability of the lobe to open up, even a little, and exert an outward force, then I'd start to question its use.

Tony Monbetsu · · Minneapolis, MN · Joined Jan 2014 · Points: 560

Absolutely not, they should have used a safety pin obviously

Lou Cerutti · · Carlsbad, California · Joined Jan 2014 · Points: 217

Haha^. Thanks for the comment Csproul

Steven Groetken · · Durango, CO · Joined Sep 2012 · Points: 390

The only thing I see that's unsafe is that hex. Commence old man comments.

Bill Lawry · · New Mexico · Joined Apr 2006 · Points: 1,546

Bad.

The hair pin keeps one lobe of the right pair contracted more than the other lobe of that pair. When the trigger is released, I doubt the designed cam angle will be as naturally preserved for that pair - math wizards out there may want to second check me.

Anyway, this simply can't bode well for the fix preserving the rated strength of the piece. I'd consider the piece as only as good as whatever the other unaffected pair of lobes can handle by themselves.

ViperScale . · · Unknown Hometown · Joined Dec 2013 · Points: 235

You are losing expansion range but as long as your placement is smaller than that level it should be fine (besides you only need the other 2 cams to hold right?)

I have seen falls on half a cam before!

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25
Bill Lawry wrote:When the trigger is released, I doubt the designed cam angle will be as naturally preserved for that pair - math wizards out there may want to second check me.
Wrong.

The cam angle has nothing to do with the triggers.
Bill Lawry · · New Mexico · Joined Apr 2006 · Points: 1,546

No. The came angle is dependent on how well centered the axle(s) is (are) between the inside faces of the crack. During release of the trigger, Uncentered-ness is promoted when one lobe contacts well before the other as in the case of this patch job.

EthanC · · Unknown Hometown · Joined Jun 2013 · Points: 259
Steven Groetken wrote:The only thing I see that's unsafe is that hex. Commence old man comments.
That's not just any old hex, that's a torque nut, those things are da bomb. Hexes for the every man.
Greg D · · Here · Joined Apr 2006 · Points: 871

Well, as mentioned, a trigger wire that interferes with the deployment of the lobes could affect cam performance if it prevents the lobes from opening to the crack width. But that trigger is affecting only the first 15-20% of retraction. Since 50-90% retraction is more ideal for initial placement that repair will not affect most good placements.

So not ideal and the repair could be better. But...

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25
Bill Lawry wrote:No. The came angle is dependent on how well centered the axle(s) is (are) between the inside faces of the crack. During release of the trigger, Uncentered-ness is promoted when one lobe contacts well before the other as in the case of this patch job.
Please explain this new found theory of yours which contradicts the very principles of a logarithmic spiral.
Bill Lawry · · New Mexico · Joined Apr 2006 · Points: 1,546

Not a theory. Just geometry. The designed cam angle can not be symmetrically preserved if the axle(s) is(are) not centered between the inner faces of the crack.

Are you of the view that the cam angle is symmetrically preserved even when not centered? Am just trying to understand exactly where our views differ before going into more detail. I'd rather not spend time arguing a specific point that we agree upon.

Ken Noyce · · Layton, UT · Joined Aug 2010 · Points: 2,122
Bill Lawry wrote:Not a theory. Just geometry. The designed cam angle can not be symmetrically preserved if the axle(s) is(are) not centered between the inner faces of the crack. Are you of the view that the cam angle is symmetrically preserved even when not centered? Am just trying to understand exactly where our views differ before going into more detail. I'd rather not spend time arguing a specific point that we agree upon.
What? The cam angle will be the same regardless of how centered the axle is in the crack. A cam lobe is a logarithmic spiral which means that the cam sngle is constant throughout the range. The only thing that not having the axle centered will do is make it so that one lobe is more cammed than the other which doesn't affect the camming angle in any way.
Chris Massey · · Unknown Hometown · Joined Oct 2012 · Points: 5

Geometry, physics, and engineering aside, it beats the shit out of not placing it at all becasuse it is left in your car or pack as broken.

patto · · Unknown Hometown · Joined Jul 2012 · Points: 25
Bill Lawry wrote:Are you of the view that the cam angle is symmetrically preserved even when not centered?
Yes. Certainly for single axles.

With double axles there are more degrees of freedom so I won't say with certainty that the effective contact angle doesn't change slightly.

By definition the actual cam angle cannot change.
Guideline #1: Don't be a jerk.

Post a Reply to "This is safe, right?"
in the Climbing Gear Discussion

Log In to Reply