RRC Archives

Thanks rick. I knew that offer was out there. I will change any placement you deem necessary on my existing routes.

At $7 a hole, it is not really a money issue. For a long term fix, that is cheap...

Someone asked me this the other day, and I didn't know the answer. With all the bolts and falls at the Lode, there seems to have been very few spinners and pull outs. Is there perhaps anything different in the design/ construction of the dyna bolt golds that is making them more suspect to loosening?

pigsteak wrote:Someone asked me this the other day, and I didn't know the answer. With all the bolts and falls at the Lode, there seems to have been very few spinners and pull outs. Is there perhaps anything different in the design/ construction of the dyna bolt golds that is making them more suspect to loosening?

There are no credible data for comparison between the two commonly-used brands of expansion bolts -- only guesses and opinions. Some people believe the Rawls-type Power Bolt has less tendancy than the Dynabolt Gold to loosen in sandstone. There are too many other contributing factors to make this generalization.

And, of course there is the definition of "very few spinners and pull outs." What is this number? I've heard from climbers who climb a few routes here and there make broad claims about entire areas being better bolted than other entire areas.

As you know, we are on the home stretch of updating a huge detailed database of bolted routes in Muir Valley. Every single bolt, hanger, and anchor has been inspected, its torque and condition checked. The brand and type of hardware used have also been recorded along with the type of topanchor extensions used. And, of course, the route developer(s) noted (So far, TWO spinners have been found in well over 1200 bolts inspected. Is this "very few spinners?" I really don't know, but it doesn't seem too bad, considering the amount these routes have been climbed.)

To my knowledge, there are no similar data from any other place in the Red with which to make fair comparisons between different areas, hardware, developers, etc. Perhaps in the future, inspections and inventory of routes will be made elsewhere. Then, and only then, will we have a more accurate picture of what's going out there on RRG climbing routes.

Rick

well said rick...much of climber spin is anecdotal....i am as guilty as the next guy of passing on legends and hearsay. thanks for doing the "almost hard" science of exploding sandstone.

A comment on the Fixe USA glue-in bolt prices: yes they are 5.40 and 6.70 for the 3.5 inch and 5 inch. But I think you can save bucks by buying from barrabes.com: http://www.barrabes.com/barrabes/dept.a ... t=&Orden=1
They are $2.35 and $3.20 respectively. The D-glue-ins look even better; the product reviewers say you don't have to fool with reaming out the start of the hole to get the ring to sink into the rock a little, and it has a giant groove to suck up the glue. I might have to get some of these babies for you to test, Rick. They are just $2.02 a pop. I would love to see a cone of rock popping out, rather than a bolt pulling. Keep up the good work!!!!!!

Bashie wrote:A comment on the Fixe USA glue-in bolt prices: yes they are 5.40 and 6.70 for the 3.5 inch and 5 inch. But I think you can save bucks by buying from barrabes.com: http://www.barrabes.com/barrabes/dept.a ... t=&Orden=1
They are $2.35 and $3.20 respectively. The D-glue-ins look even better; the product reviewers say you don't have to fool with reaming out the start of the hole to get the ring to sink into the rock a little, and it has a giant groove to suck up the glue. I might have to get some of these babies for you to test, Rick. They are just $2.02 a pop. I would love to see a cone of rock popping out, rather than a bolt pulling. Keep up the good work!!!!!!

Thank you, Bashie, for the info on a less expensive source for FIXE hardware. When I checked with Barrabas a few months ago, the shipping charges were pretty high. I just re-checked a typical order for FIXE hdw from Barrabas at 63 US$ and the shipping charges (including fuel tax) was 54 US$. This kicks up the $2.35 bolt cost $4.36 landed in the U.S. Still a bit better than the $5.40 price.

Rick

In reading all of this, I've been asking myself "how much force CAN a falling climber exert on a bolt?" I dug out the Climbing Wall Industry Group's Specifications for Manufactured Climbing Walls (1993 version). This document is a guideline for designing climbing walls, so it seems to be more oriented to the terms of architects and structural engineers, rather than the engineers who would design an actual bolt or hanger, for instance.

While there's a lot to it, but basically, they define the live load exerted by a falling climber as a 2000 daN (4400 lb) impact force that must be accomdated both straight down and at a 12.5 degree angle from vertical. They don't define the duration of the impact, so, as an architect, I would think of it as a fairly 'static' load for evaluating the strength of a structure. This section appears to be guidelines for the design of the overall climbing wall structure so it's telling the structural engineer what sort of load will be applied to the overall structure from any given bolt point.

In terms of evaluating a particular 'bolt' they offer fairly similar guidelines. They specify a 'radial resistance' load of 2000 daN (4400 lbs.) (I'm assuming that means a force applied perpendicular to the bolt) and an 'axial resistance' load of 1500 daN (3300 lbs.) For both, the test should apply the force 5 times for a duration of 5 seconds with a 10 second rest between loadings.

Is that a good guideline for testing bolts in real rock? I don't know. At first, it sounded like an unrealistically high load. Here's how I'm thinking about it: I weigh, uh, slightly more than 200 lbs. If I experience 6 Gs during a fall, then I am exerting 1200 lbs. on my end of the rope. My belayer is exerting an equal force to stop me (ignoring friction, etc.). That totals to 2400 lbs on the bolt. That's quite a bit shy of 4,400 lbs. I guess that you would have to come up with some sort of 'worst case' scenario: the belayer is using a grigri AND is jammed up against the first bolt AND the leader is taking a huge fall DIRECTLY ON that same bolt. Hmmmm.... Is there a physicist in the house?

I guess as a matter of 'policy' that the system should be designed so that 'body retreval' is easy. That is to say, even though the human body can only withstand so much force, the bolts and gear should be designed to withstand MORE than that amount of force, just on principle.

I am sure that 5 repetitions is way too few for testing bolts on outdoor routes in real rock.

(Keep in mind with all my comments that I'm an architect, not an engineer, so there is tons I don't know about this sort of thing!)

tomdarch wrote:In reading all of this, I've been asking myself "how much force CAN a falling climber exert on a bolt?..."

There are so many variables that can enter into the equation that it would be very difficult -- but not impossible -- to mathematically model the load on a bolt created by a falling climber. Kinda hard to quantify how much stuff stretches. That 6-G load you refer to when applied uniformly to a human body -- say in an F-16 doing an inside loop -- creates a pretty tolerable load. But, concentrate the 1200 pounds (in your case) on your harness, and your guts are gonna hurt mightily!

Actually, there is a very easy way to get an answer to this question. And, it is one that we may want to try to do here later. You simply hang a load cell (strain gage bridge) on a hanger bracket and clip a quickdraw/rope/climber to the other end. Connect the load cell to a portable computer via a Dataq and voila -- dead accurate data at 200 samples per second. (Uh... let's not say "dead" here.)

My guess is that the force vs. time plot that you would get from this setup would show a relatively gentle loading on the bolt (hanger bracket) during a typical whipper. Nothing in the neighborhood of 6 G's. But, of course, I could be wrong.

Tell you what -- I'll provide the test instrumentation and load cell and the "laboratory" (a wall at Muir with a particularly strong glue-in bolt for the point of loading.) And one of you out there can loan us a portable PC. My portable is a Mac, and my Dataq software runs on Windoze. Then, all we need to fill out the experiment is a test dummy. (God knows, we have enough of these Victory-Whipper-taking lunatics down here from which to draw from.)

Right now, I'm trying to put a house construction to bed. But, I'll start gathering up the stuff to make this happen fairly soon, okay?

Rick

I'll bring my laptop and would love to take some falls of varying lengths. Would be interesting to do multiple drops with different belay devices as well.

I'm curious to see the results of actual live dynamic falls.

Concerning what tomdarch wrote, 20Kn falls { 2000 daN (4400 lb)} are not regular occurances...biners amongst other things have been know to deform under such strain. I'm not sure if it's been mentioned before in this thread or others but petzl has a decent fall simulator on their website that provides rough numbers for the curious.

http://en.petzl.com/simul/FC/index.html

Thanks for the continued research and stewardship Rick, it's appreciated.

Cheers,

Brent

drifter wrote:I'm curious to see the results of actual live dynamic falls.

Concerning what tomdarch wrote, 20Kn falls { 2000 daN (4400 lb)} are not regular occurances...

Let's hope so. Powers and Dynabolt Golds fail when radially loaded (perpendicular to the long. axis of the bolt) in this force range. Ours have been losing their heads in the mid 4000's.

Rick