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danpayne
Feb 4, 2005, 7:56 AM
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ok, quick question for all you engineers/trad climbers out there. Say I place my BD C4 Cam into a horizontal crack, Is there a better direction? What I am asking by this is, should the outer lobes (colored) be contacting the top or the bottom, or does it even matter?
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bilias
Feb 4, 2005, 8:13 AM
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I was always told that the outer lobes should be touching the bottom of the horizontal crack. But that's just what I was told.
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stzzo
Feb 4, 2005, 8:17 AM
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Gotta go by the specific situation, seeing how the lobes hit the irregularities of the crack, but rule of thumb is that - if possible - putting the outer lobes on the bottom gives it more stability.
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gunked
Feb 4, 2005, 11:11 PM
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I'll second that. :wink:
If it's a parallel sided crack with few irregularities like often found in granite, outer lobes on the bottom would be preferable.
If it's an irregular shaped crack such as those found in the Gunks (quartz conglomerate), the placement has to be tailored around the irregularities of the rock, being ever aware of rotten rock, crystals, shallow placement, cams working in unison, dirt, crack opening up as it gets deeper, rigid stem possibly shearing over an edge, etc...
Did I miss anything?
-Jason :D
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nthusiastj
Feb 4, 2005, 11:18 PM
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I'll third that.
I believe this is also covered in John Long's climbing anchors book.
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jt512
Feb 4, 2005, 11:19 PM
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In reply to: ...but rule of thumb is that - if possible - putting the outer lobes on the bottom gives it more stability.
I've never heard that before. Is that really true, or is this a new urban legend in the making?
-Jay
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bandycoot
Feb 4, 2005, 11:26 PM
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Jay, you beat me to the same question. To all those saying outer lobes on the bottom: WHY? :?:
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fracture
Feb 4, 2005, 11:28 PM
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In reply to: In reply to: ...but rule of thumb is that - if possible - putting the outer lobes on the bottom gives it more stability. I've never heard that before. Is that really true, or is this a new urban legend in the making?
I've got no information about whether it is true, but I have heard people say this for both TCU's and Tricams (IIRC, one of those is mentioned in MFOTH---of course, microcracks are mentioned in MFOTH also, so who knows).
To the OP: you can always email black diamond if you want a real answer. If you do, please post the response here. 8^)
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clymber
Feb 5, 2005, 12:30 AM
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i agree withthe otheres that said the outter lobes on the bottom....reason why is that theres abigger foot print of the cam and less likely it will flip over...yes i iknow there are exceptions to every rule but thats the way i was told by my guide friends
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one900johnnyk
Feb 5, 2005, 12:57 AM
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you know, this is really a more pertinent question when you're talking about something like a tcu where there is a greater difference. i like the outer lobes on the bottom but i've heard the case also that when you fall on a horizontally placed tcu and think about what it wants to do, you'd put outer lobes on top. the cam will want to rip out of the crack from the top due to the torque when weighted so you'd rather have more friction up there... i studied physics and i still can't really decide. there are so many factors involved, if you're six inches to the right of the placement when you fall it could change everything... good luck figuring this one out!
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dirtineye
Feb 5, 2005, 1:19 AM
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IT does not matter which way the lobes are, as long as all other things are equal.
GO with the best fit, outside lobes up or down depending on fit.
THis is one of those dead horse topics. You could probably find an old thread that discusses the reasons in detail.
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gunksgoer
Feb 5, 2005, 2:33 AM
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i always place my cams with the outer lobes on the bottem, unless crystals or other funky features make the outer lobes better suited to face up. Even if this does nothing to increase stability or holding power, a horizontal cam with the outer lobes facing up looks kinda weird, and when im trusting my life to weird looking gear my confidence meter tends to drop. so, since as far as i know the physical properties are the same for each placement, im going to go for the mental edge. :D
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danpayne
Feb 5, 2005, 10:39 PM
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ok, I sent this letter to Black Diamond,
Sub: C4 placement question
Hi, I recently purchased some of your C4 SLCD's and just had a quick question about them. Now, I understand that each placement is unique, and there are exceptions to every rule. My question to you is, in a horizontal crack, all things being equal, is a C4 more stable with its outer (Colored) lobes contacting the bottom of the crack, or the top of it. Also, does it make that much of a difference? I look forward to your response.
Thanks in advance,
Dan Payne
I will post their reply as soon as it is recieved.
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rockguy
Feb 6, 2005, 1:02 AM
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In reply to: GO with the best fit, outside lobes up or down depending on fit. |
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dirtineye
Feb 6, 2005, 1:34 AM
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The question about Three cams is interesting.
I have not used my TCUs since I got Zeros. When I saw the post about the single middle lobe vs the outer two lobes, at first I thought, "Well, the middle lobe has the same contact area as the two outsides lobes, what's the difference?".
But then I remembered that I don't always remember so well, and I got out the old Brown & Sharp caliper, and lo, the stupid lobes have different contact areas on the two side vs the one side.
Now assuming that a cam exerts the same force on one side as the other, the single lobed side gets more force per square inch than the two lobed side in a fall.
This might not matter, then again maybe it does, but I'd like to know why metoleus did it that way.
And back to the original question, I still do not see how, in a decent horizontal placement, (not too shallow) it can make a difference even with three cams.
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curt
Feb 6, 2005, 2:51 AM
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I also think it doesn't matter if the outer cams are "up" or "down" as far as holding power goes. The more important thing is which way the cam fits better in the horizontal crack--in that regard. After all, a cam with a 14 degree cam angle will exert an outward force on the crack that is roughly twice the downward force on the stem.
Curt
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jimdavis
Feb 6, 2005, 5:19 AM
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Yeah, fit is way more important than outer/ inner lobes.
It matters more for tricams, as they don't have springs holding them and stability is more of a concern. But fit still over-rides that notion, just set em nice!
Cheers,
Jim
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irockclimbtoo
Feb 6, 2005, 2:58 PM
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ab
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one900johnnyk
Feb 6, 2005, 3:02 PM
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this question is just not interesting unless you're talking about it ceteris paribus, so that's how most people took it i think... of course fit is paramount....
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dirtineye
Feb 6, 2005, 3:33 PM
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You people claiming there is greater stability with the outer lobes on the bottom, please explain just how any lobe of the cam moves without the others moving.
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murf
Feb 7, 2005, 4:09 PM
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Please!! Regardless if one is stronger than another, how much freaking stronger is it? Which one of you nimrods gets to a horizontal, puts in a piece that looks fantastic, no ridges, ruffles, or rough edges interfering, and then say to yourself....
"WHOA! The [outer|inner] cams aren't [down|up], I might *die*!!".
If this describes you, dump that rack on eBay. This is trad climbing people, pedants and pansy-asses need not apply.
Murf
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danpayne
Feb 7, 2005, 8:51 PM
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I recieved this reply from black diamond
Hey Dan-
Thanks for the email. I think I understand your question. So you are talking about the colored lobes touching the bottom of the crack or the top of the crack right? The answer is, it doesn't matter. Either way is the same. I hope this helps. Please let me know if you have any other questions. Thanks again.
Best Regards,
Mike D
Black Diamond Equipment
2084 East 3900 South
Salt Lake City, UT 84124
801-278-5533 x1102
miked@bdel.com
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petsfed
Feb 7, 2005, 9:15 PM
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I read that in FOTH, but they never qualified it so....
Go with what fits and what's fast. Anything else is secondary.
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wlderdude
Feb 8, 2005, 1:35 AM
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I have heard/read that the wide lobes on the bottom is generally preferd, and it makes sence to me. It is more stable, but why?
Okay, here is your scientific explination.
The wider apart the cam lobes are, the more "stable" it is. It is really only an issue in larger sized cams (full hand+). A cam with more stabilty will move around less, walk less, be less likely to tweak funny, etc.
If the cam lobes are weighted exactly the same, it doesn't matter which is on top, it will be just as stable. When you see a vertical crack cam model, the lobes push exactly the same.
But this is not often the case in horizontal cracks. With cables, the force is always in the dirrection of the cable. So, if the cable is pulling down, it is putting more force on the lower lobes than the upper lobes. More force on the lower lobes will mean more stabilty if the lobes are spread apart.
Naturally, the deeper the crack, the less advantge you will get from positioning the wider lobes on the bottom, because the stem will be more in line with horizontal.
If you are anticipating upward pull, put the wider lobes on the top.
So there you go. Let me know if you need a picture.
Put a cam in your hand and feel for yourself.
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