RRC Archives

hey rick, will you be testing any smaller bolts (3/8" or 1/4")?

If any of you route developers out there would like a particular piece of hardware tested, please get me a sample. Hugh, Blake, Terry? If you want to test on rock in the MPRP, then you'll have to help carry old Arnold down there.

Rick

Horatio Felacio wrote:hey rick, will you be testing any smaller bolts (3/8" or 1/4")?

Good question. I plan on testing the 3/8-inch Fixe Wedge Bolts, but they are approximately the same size bolt as the ones inside the 1/2-inch Dynabolt Golds and 1/2-inch Rawl 5-piece bolts.

Let me clarify a little here. The 1/2-inch Dynabolt Golds and 1/2-inch Rawl 5-piece bolts are 1/2 inch in diameter over the outside sleeves. The bolts within them are only 3/8 inch diameter (16 tpi). The 3/8" Fixe Wedge Bolt is flush with the sleeve.

I am also going to be testing 3/8-inch dia. threaded rods made of stainless steel that are anchored with adhesive in a 7/16 inch diameter hole. In fact, on the test wall along side the trail down from the main Muir Parking Lot, there is one of these embedded and waiting to be tested.

Because the American Safe Climbing Association strongly opposes bolt sizes less than 3/8 inch in diameter, I don't think I'll be testing smaller sizes. We definitely will not allow anything smaller than 3/8 inch dia. and less than 3.75 inch long to be used in Muir.

Rick

Is it plausible that the "soft" quality of the corbin sandstone actually acts as a buffer or shock absorber, allowing the bolt to fall back on its tensile qualities as it deforms down as the rock crushes under it?
I saw that Eric's bolt (Triplex by fixe?) faliled at a lower force than the dynobolt gold. Eric's bolt failed in shear force where the dyna bolt gold failed, as you said, in a tensile force.

the lurkist wrote:Is it plausible that the "soft" quality of the corbin sandstone actually acts as a buffer or shock absorber, allowing the bolt to fall back on its tensile qualities as it deforms down as the rock crushes under it?

Have to think about this one. Of course, shear strength and tensile strength for a ductile metal are not the same. It's almost midnight. I'll post more on this later.

I saw that Eric's bolt (Triplex by fixe?) faliled at a lower force than the dynobolt gold. Eric's bolt failed in shear force where the dyna bolt gold failed, as you said, in a tensile force.

When you look at the photo of the Fixe bolt, you can see that it broke about an inch inside the sleeve. It appears that the downward force on the hanger actually pulled outward (axially) on the bolt, and it failed in tension. There was no shearing force applied at the point of the break.

Rick

Rick, tell us about the chain and quick-links (size, brand, etc.) used in the tests. From the photos they appear to be the standard hardware store variety. Maybe you could test the other hardware in the anchor system too. I too have been breaking bolts, though in an absolutely non-scientific method. When re-equiping (more scientific sounding than re-bolting, not to be confused with retro-bolting) routes, instead of hammering stud-type bolts back flush with the rock or trying to pry the bolt out (bad idea, this really scars the rock), I just over-torque until failure. I know, in actual use the bolts see very little torque loading, but this method does yield useful information. What I have found may be of interest to those interested in such interests. The vast majority of the bolts I have broken this way were really solid. However, some of the bolts (slabby routes exposed to more moisture) failed with very little force. I could probably have over-torqued them with a pair of pliers. These bolts looked as good as the much stronger bolts. You really can't tell by looking, as the more serious rust takes place out of sight inside the hole where less drying takes place. I am much more suspect of old gear on slab routes than the steep stuff. When folks ask about gear for the Red, I always reply that the Red takes bolts really well!

the lurkist wrote:Is it plausible that the "soft" quality of the corbin sandstone actually acts as a buffer or shock absorber, allowing the bolt to fall back on its tensile qualities as it deforms down as the rock crushes under it?

I think it's a matter of how fast the bolt is loaded. A standard tensile or compression (and even Rick's testing and the UIAA testing) applies fairly slowly. This allows a material to slowly increase its strain until it first hits its yield point, then eventually its ultimate tensile/compression strength. In real life, we don't load bolts slowly; it's a VERY fast load. There is almost no time for a material to deform at its yield point as it is quickly strained to its ultimate(breaking) point.

Rick, you said you had planed on testing threaded rod. What alloy and grade are you trying? Thanks for doing all the testing.

dhoyne wrote:There is almost no time for a material to deform at its yield point as it is quickly strained to its ultimate(breaking) point.

dhoyne;
Not to be snarky, but I am surprised at this statement. How fast (or I should say how slow) do you expect a strain to travel through a piece of metal? In the press business, metal is deformed pretty fast without cracking. Factories like the high production rates. Not as fast as, say, a bullet when it shatters against concrete, but we are not loading bolts quite that fast either. Again, not trying to call you out or anything, just interested in the discussion.
M.

Sunshine wrote:Rick, tell us about the chain and quick-links (size, brand, etc.) used in the tests. From the photos they appear to be the standard hardware store variety. Maybe you could test the other hardware in the anchor system too.

We have a pretty wide variety of hardware -- some specifically designed for climbing, and some from "hardware" suppliers. The hangers are all from climbing gear companies, such as Fixe, Metolius, and Petzl. The bolts are from Fixe, Powers (formerly Rawl), and ITW Red Head. Chain and quick links are the better quality types purchased from McMaster Carr. The quick links are 3/8" with an SWL of 2200 pounds and an ultimate strength around 9000 pounds. The 3/8" chain is grade 30 or above.

I hope to test other hardware components, and in fact have used the same 3/8" quick links and chain in the tests of the bolted hangers with no signs of failure. The test gear is safe only to about 8500 pounds. Anything beyond that for climbing purposes is overkill in my opinion.

Sunshine wrote:...The vast majority of the bolts I have broken this way were really solid. However, some of the bolts (slabby routes exposed to more moisture) failed with very little force. I could probably have over-torqued them with a pair of pliers. These bolts looked as good as the much stronger bolts. You really can't tell by looking, as the more serious rust takes place out of sight inside the hole where less drying takes place. I am much more suspect of old gear on slab routes than the steep stuff. ...

A good case for stainless steel bolts or glue-ins on slabby routes.

Rick