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tnd
01:30:08 Tue
Oct 17 2006

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Re: Testing of Rock Climbing Anchors

Quote: Glenn_Short at 09:20:07 Mon Oct 16 2006

Mind you, I also think that mostly the glue and anchors are so overkill that they'll be more than good enough for climbing.


Back at work Glenn? I bolted that slab beside Jugantor at Mt Boyce. It's on Roger's web site now. Grade 19. All on U's! :wink:

I think we get away with slightly less than perfect practices because we don't generate the same loads on the bolts. An engineering fixture is permanently loaded (by having a nut tightened on the threads) with a force trying to pull the stud straight out. Our fixtures are often never loaded, and when they are the load tends to be more or less perpendicular to the shaft.

I prefer to use epoxy rather than the cheaper acrylic because it is stronger and helps make up for not being able to rotate the U bolts.

hatman, I've found that with Steve's commercial U's (with consistent dimensions) you can make up a drilling jig and get the holes pretty well perfect every time.
[1 edits; Last edit by tnd at 01:31:54 Tue Oct 17 2006]

  
bundybear
02:09:12 Tue
Oct 17 2006

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Re: Testing of Rock Climbing Anchors

Quote: tnd [br

hatman, I've found that with Steve's commercial U's (with consistent dimensions) you can make up a drilling jig and get the holes pretty well perfect every time.



Yeah. Me too - they are great. EZ to get parallel perfect holes all the time.

  
hatman
07:24:23 Tue
Oct 17 2006

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Re: Testing of Rock Climbing Anchors

I see, having two legs must be an advantage over a ring as well?

but me thinks its a moot point, they are both satisfactory for what we ask.

  
rogerb
02:42:18 Thu
Oct 19 2006

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Re: Testing of Rock Climbing Anchors

OK, own up! Who asked for that ring bolt at Woranora to pull out and send Martin into the deck?

  
Glenn_Short
06:53:31 Fri
Oct 20 2006

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Re: Testing of Rock Climbing Anchors

Very Qwick Wodger. Seeing that he survived, I was glad - that was some bruising on the back half of his body, would have hated to miss seeing it! (Sorry Marteen:smile:

Wasn't it a U bolt that hadn't been put in properly?? I figure the only certainty with my climbing anchors is that I WILL fall on them! (If I can get high enough on the route to clip them - with a long stick - or a lasso - or send Pam up)

Gkneaghall, your pieces of art at Medlow and Boyce do indeed look like masterpieces. Hope to get on them soonish, shall speak glowingly about them if I don't get scared. And yep, back at work, thanks for reminding me.

Cheers

G.

  
phm
16:14:15 Fri
Oct 27 2006

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Re: Testing of Rock Climbing Anchors

Just a few responses to comments made earlier in this thread:

Roger, you are correct in pointing out that in Figure 10 some of the highest failure loads were measured for U bolts – but also some of the lowest. That means, that the spread of the results was found to be much greater for Us than for Ps. A common way of nominating a ‘design strength’ for a bolt would be to use a value one (or two) standard deviations conservatively away from the mean test result. And this value was found to be worse for Us than for Ps due to the greater spread of test results.

Glenn, I agree, buttering is an inadequate method of ensuring mechanical bond between bolt and glue. With U-bolts twisting is not an option – hence my previous comments about Us. I also have a problem with capsule glue – namely with the fact that the quantity of glue is pre-determined. This is problematic in soft rock where hole diameters often differ significantly from the nominal diameter of the drill bit (or your tooth brush for that matter). Also, on steep climbs capsules are very difficult to use.

Hatman, yes indeed, some of the commercial anchors are clearly not designed to give high strength in soft rock. I am not sure what you mean with trad anchors.

Tnd, I disagree with your comments about engineering structures. An airbag in a car is only ever loaded once, but then the probability of the airbag working properly in this one case should be very high. Similar principles apply for climbing anchors in my opinion.

Hatman again, yes two legs in a U are certainly an advantage – but only if both legs work properly. If one leg fails, the whole anchor fails.




[1 edits; Last edit by phm at 19:04:58 Fri Oct 27 2006]

  
Glenn_Short
07:47:30 Mon
Oct 30 2006

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Re: Testing of Rock Climbing Anchors

Hi Martin, Great to hear from you. Was really nice to see you the other day. Let Gerda know that Katie loves her Austrian smiley face!

Yeah, I know, capsules have their limits. That's why some of my routes have 6inch bolts cartridge glued in at the crux! Hey, I'm even contemplating putting in some rings! (Blame Giles) Have to start climbing harder so I can clip em.

Keep the good info coming. Some of those bolts are starting to scare me and I don't have much fear threshhold left!

Cheers

G.

  
Miiiitch
06:51:30 Fri
Dec 1 2006

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Re: Testing of Rock Climbing Anchors

Hatman- " having two legs must be an advantage over a ring (single leg) as well?"

-Drilling a hole in rock creates micro fractures in the rock around the hole..... when drilling two holes close together these fractures can link up and create a weakness in the rock.
Has anyone ever told you to drill close (350mm) to a crack or another bolt ???? Have you ever wondered why bolts aren't drilled near cracks or other bolts???? U-bolts consist of two holes drilled much closer together. No one in their right mind would put two individual bolts that close together.... why is that?
As rightly said by someone else before, if one of these legs fail... both fail... there is no redundancy with U's.
It scares me when someone writes on a forum that U-bolts are the strongest anchors around.... I know you only mean well but the long term reliability of them is very questionable in my books.
I make no claims at being any sort of expert.... actually i would be lucky if i could pass myself off as an idiot :smile: ...
however... everywhere i look on the internet I see warnings about U bolts.... there seems to be many better alternatives... save your drill's battery power, take the time and put in a ring bolt... someone will be very grateful 10 years down the track.

For a more trustworthy source try this guy:

Glue - Inswww.climbargolis.com/Glue-inBoltDesign.htm


if u scroll through the tech data its plain to see this guy knows his bolts, tests anchors up to 75Kn!!! When was the last time you belayed a elephant?
Describes anchor failures as bolt, glue or rock related.

To continue with my laymans ranting: it's nice to have pretty little graphs showing breaking points of different anchors, why dosent someone conduct these tests in sandstone instead of concrete (chossy weak sandstone aswell!).... i don't climb concrete... do you?
Is concrete really a suitable substitute for sandstone (any rock for that matter?) just because they might break at similar forces? does concrete and sandstone behave the same when you drill big holes in them? Are they chemically similar?....

Not too completely rip up U's..... I think they make kickass rap anchors. Don't like them as lead anchors but i still use 'em (somethin always better than nothin)

Peace.




  
shawkshaw
07:34:32 Fri
Dec 1 2006

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Re: Testing of Rock Climbing Anchors


  
hatman
20:39:52 Mon
Dec 4 2006

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Re: Testing of Rock Climbing Anchors

there is also no redundency with rings miiiiiiiiiiiiiiiiiiiiiitch, my thoughts were that there is more anchor to rock, surface for adhesion with a U, also no posibility of twisting and breaking the bond. This was not a state ment, it had a ? mark behind it.

I am also no expert, and before you go making spite full (although perhaps acurate) comments about the state of my mind I suggest you read my posts again and see that I was just trying to draw a conclusion from the data.

I was not stating that I thought U's are the best option. In fact currently all i use is rings. Although in the past I have placed a few U's as lead anchors and taken many and repeated falls on some of them no problems.

  
Cragx
20:52:04 Mon
Dec 4 2006

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Re: Testing of Rock Climbing Anchors

Dont worry Hatty, we all know your true expertise is abseiling.

  

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