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adatesman


Mar 31, 2008, 3:22 PM
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Partner j_ung


Mar 31, 2008, 3:34 PM
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Re: [adatesman] Things people want pull tested [In reply to]
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Dude, I just have to say, you and your muh-cheen fuckin' rock. I think this is an awesome addition to the site.


irregularpanda


Mar 31, 2008, 3:54 PM
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Re: [adatesman] Things people want pull tested [In reply to]
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OK

Um, regarding rappelling: a fatty 10.5 tied to an 8 mil or less with an EDK and with a figger8 follow through.

Double bowline attached to a harness.

(so expensive I'm sure it won't happen) an OP link cam placed in a flare and a trango max-cam placed in a flare.


taydude


Mar 31, 2008, 4:24 PM
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Re: [irregularpanda] Things people want pull tested [In reply to]
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do a pull test on one of those aluminum rap rings to shut up that paranoid guy.


adatesman


Mar 31, 2008, 5:32 PM
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irregularpanda


Mar 31, 2008, 5:42 PM
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Re: [adatesman] Things people want pull tested [In reply to]
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adatesman wrote:

You never know... we come up with a particularly interesting test someone might pony one up. What kind of flare / load you have in mind? Outward or downward flare? Direction of loading? Binding on any of the lobes? A downward flare could probably be done without much damage to the cam. I suspect an outward would be more likely to damage the cam due to the lowered surface area (side note- I recall seeing a patent about this recently and will see if I can dig it up).

You know, I'm not a huge physics geek, so to be honest, that should probably be up to you. My gut reaction is this: Outward flare. Downward load. The problem with an outward flare is that there could potentially be so many different angle of flare that it becomes a question of "at what point will the OP link cam or the trango max cam break?"

OOOOHHH new thought: an outward flaring placement with a downward direction of pull could be fascinating for standard friends, camalots, and chocks also. Imagine one of those big honking WC rocks placed in the tapered position with perfect surface area. Do you have a hi-speed camera?

So many variables, not enough toys.


adatesman


Mar 31, 2008, 6:01 PM
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moose_droppings


Mar 31, 2008, 7:27 PM
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A cheap simple one, 7mm tied together with a water knot.
If testing has been done on this, point me to it.
Thanks


marde


Apr 1, 2008, 8:24 AM
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Re: [irregularpanda] Things people want pull tested [In reply to]
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irregularpanda wrote:
OK

Um, regarding rappelling: a fatty 10.5 tied to an 8 mil or less with an EDK and with a figger8 follow through.
...

that might answer your question
http://www.gudelius.de/spst.htm

at least the most important stuff is in english, too.


acorneau


Apr 1, 2008, 9:10 AM
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Re: [marde] Things people want pull tested [In reply to]
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marde wrote:
that might answer your question
http://www.gudelius.de/spst.htm

at least the most important stuff is in english, too.


WTF... deka-Newtons?!? Crazy


(This post was edited by acorneau on Apr 1, 2008, 9:11 AM)


marde


Apr 1, 2008, 11:04 AM
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http://en.wikipedia.org/...onal_System_of_Units
1 deka Newton = 10 Newton


acorneau


Apr 1, 2008, 11:09 AM
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marde wrote:
http://en.wikipedia.org/...onal_System_of_Units
1 deka Newton = 10 Newton


Yeah, I know. But when the rest of the world uses kilo-Newtons....
Crazy


marde


Apr 1, 2008, 11:20 AM
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come on,
kilo, deka are just prefixes used by the si system

why do you use half inch and quarter inch
when everyone is using inches???

I guess you are able to divide or multiply by ten


tradklime


Apr 1, 2008, 11:26 AM
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Re: [adatesman] Pull Test Suggestion Thread [In reply to]
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I'll definetly send you the cam and the quick links, and anything else I dig up that may be of interest. I have a couple of old SMC rings sitting around I'll send you too.

Regarding the quicklinks, how many do you think would be needed to make the results somewhat representative? 5? 10?


adatesman


Apr 1, 2008, 11:46 AM
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cushman


Apr 2, 2008, 3:26 PM
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adatesman wrote:
6. 4/2/08 - Christmas comes early thanks to Mark Cushman! (Sorry, he didn't give his RC username...) All sorts of goodies to destroy

Hey, that's me. I shipped out the package to you today via USPS, you'll probably get it early next week. Have fun breaking the stuff!


shoo


Apr 2, 2008, 5:12 PM
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Re: [adatesman] Pull Test Suggestion Thread [In reply to]
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adatesman wrote:
tradklime wrote:
I'll definetly send you the cam and the quick links, and anything else I dig up that may be of interest. I have a couple of old SMC rings sitting around I'll send you too.

Regarding the quicklinks, how many do you think would be needed to make the results somewhat representative? 5? 10?

Yikes, I'm no statistician; just an ordinary guy who likes to break things. Tongue

I'll break whatever you send, so perhaps there's someone else around with experience in the field that could weigh in on the subject?

-a.

Statistician here (actually economist, but in this case it'll do). I can do a couple of things for you with regards to determining the number of links that are needed to get "representative" results.

1. Calculating a 95% (or any other % for that matter) confidence interval is really easy given the results. This basically gives you a range which you can be 95% sure (sort of) that these biners will fail within a certain range. You can do this with any number of biners tested. The more you test, the smaller the interval.

2. If you know the range you want (like, I want to test my biners so I can expect with 95% confidence that other biners of the same type will fail within 1kn of the average tested) and the variance (a measure of how different the results for each biner were), I can tell you how many biners you need to test to achieve this. Unfortunately, that means you already have to do some testing to figure out the variance.

3. If you want to get really fancy and you have lots of data, I can run some regressions for you to do some more in-depth analysis. Example, you want to test how much different knots slip with different materials. You test a bunch of knots with a bunch of different materials. I take the data and can approximate how much each factor contributed to the resulting slip.

Unfortunately, there really isn't a way to tell you how many biners you'll need to break to get representative results without knowing the variance, standard error, standard deviation, or something along those lines. The easiest thing to do is to give me the results and I'll make a 95% confidence interval. Obviously, the more you test, the better.


(This post was edited by shoo on Apr 2, 2008, 5:23 PM)


no_email_entered


Apr 2, 2008, 5:39 PM
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how 'bout a nalgene?---
http://www.rockclimbing.com/...ar_demand_78512.html





----seriously


adatesman


Apr 2, 2008, 6:00 PM
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adatesman


Apr 2, 2008, 6:22 PM
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shoo


Apr 2, 2008, 6:39 PM
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adatesman wrote:
Hey Shoo,

So if I'm hearing you correctly (and vaguely remembering what little statistics I slept through in college many, many years ago), obtaining the degree of certainty has more to do with having samples with similar results than having a huge pool of samples?

It has to do with both.

*Turn away if you don't like math*

<Range of predicted values> = <average value> +/- [t * s/sqrt(n)]

where t is 1.96 at 95% confidence, s is the standard deviation of the sample, and n is the size of the sample (i.e. number of observations). The latter term is half the size of the confidence interval (see the +/- there?)

Basically, what you should do is break a bunch and message me the results for each biner. I'll throw you back some statistics, like standard deviation, the 95% confidence interval, etc. If everything breaks consistently, you might get some good results. Who knows.


(This post was edited by shoo on Apr 2, 2008, 6:41 PM)


Jbitz


Apr 2, 2008, 7:28 PM
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Re: [irregularpanda] Things people want pull tested [In reply to]
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I would like to see the double bowline with a double fisherman backup tested with and without the yosemite backup.

The only data I have seen in the past is on the single bowline often comparing it to the figure-eight.


(This post was edited by Jbitz on Apr 2, 2008, 7:30 PM)


adatesman


Apr 2, 2008, 7:33 PM
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JesusNut


Apr 3, 2008, 10:05 AM
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Im a little curious about this one, maybe no test needd and its just common sense, but, Is it better to join two slings with a girth hitch or a biner? Lets say its a top rope and there was some slack when I fell. Or its off a lead and I extended a piece with two slings and I fell? What would work better or safer? (Two slings being equal in all aspects)


basilisk


Apr 3, 2008, 10:16 AM
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JesusNut wrote:
Im a little curious about this one, maybe no test needd and its just common sense, but, Is it better to join two slings with a girth hitch or a biner? Lets say its a top rope and there was some slack when I fell. Or its off a lead and I extended a piece with two slings and I fell? What would work better or safer? (Two slings being equal in all aspects)

You may be interested in the tests Black Diamond did:
http://www.bdel.com/...p_archive.php#110906

This may interest you too:
http://www.bdel.com/...p_archive.php#052107

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