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JLP
Social climber
The internet
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I'm focused on that ring. I doubt it's machined in, but possible. Machining is slow and expensive in Ti.
If it's pressed or rolled in, then the break happened right where the metal would yield the most during the process.
Any comment here on how that feature is put in?
The other bolts on the market use less agressive and intrusive features for the glue.
If the bottom of the ring were 8mm diameter, the bolt would be less strong than an equivalent 8mm rod, even less so if the metal was just yielded.
sigma = My/I for an 8mm rod is ~1E10 pa, with Ti alloys snapping at around 9E9 - assuming a 1kN load 5 cm from the break, normal to it. The 1E10 Pa # will actually be much less given the geometrey of the ring (it's a "stress riser"), and any possible yielding during manufacture.
Basically, the bolt design seems weak to me.
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Jay Wood
Trad climber
Fairfax, CA
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In the photo of the broken bolt end, you can see that the weld is opposite the shiny part of the break. So the bolt would have fractured until there was a thin section of metal left, which would bend before failing- like the 'hinge' when falling a tree.
From the in- place photo, it doesn't appear that the rock is cratered. It looks like it just wasn't inserted all the way.
P.S. I love my titanium (carpentry) hammer, and tried to love the Ushba nut tool, but the wire gate clip fell apart.
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dirtineye
Trad climber
the south
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Jay, that clip was a DUMB idea. and I told em so.
I had three of the old ones, they ROCKED. WEll they still rock, but I ground away the tip of one digging dirt out of cracks, and traded one to RRK, who since he never cleans anything, has a mostly perfect pre-clip Ushba nut tool.
I need to steal it back.
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Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
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Well it certainly looks like my $100.00 is safe (to be honest, I was worried there for a sec).
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Brian in SLC
Social climber
Salt Lake City, UT
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Basically, the bolt design seems weak to me.
I don't think so. The bolt really should never have been loaded in the area of the groove/notch. That notch should be buried subsurface.
I swung the pictures by a metalurgist. Their comments were pretty consistant with a recent bolt failure we had here. Overload failure. Not initally maybe an installation issue, but, either the bolt wasn't installed deep enough, or, the rock cracked out under it. That created a pretty big moment arm in the bolt. Combine that with a now exposed notch, and you have a big stress riser. The shiny metal in the cross section picture indicates that there was a crack, for probably some time, maybe even years. Over time, it got a little bigger.
Although its hard to see in the picture, there appear to be parallel stop arrest ridges or striations along the direction of the crack. Also, there doesn't appear to be fatigue indications based on the surface (no cupping smiley faces facing towards the shiny crack).
So, I don't think its a bolt design problem. The bolt was darn strong enough for many years of dogging on it. Sooner or later, the small crack was going to reach critical flaw size and an overload failure was going to happen.
You could maybe poke at how the grooves/notches got in the bolt, but, they look pretty smooth to me. It'd be easy to imagine the bolt bending and developing a crack through repeated loading right there at the stress riser notch.
Would be interesting to get some high res. shots of the cross section surface.
Bottom line? Don't repeatedly fall on a bolt who's shaft is sticking part way out of the rock...
Coulda tied it off with a sling...ha ha. (Seriously, probably wouldn't have busted for years if it was tied off above the eye).
-Brian in SLC
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dirtineye
Trad climber
the south
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Hey ya know, there is no glues residue on the bit of bolt.
I thought HK said the new glues were super strong. Shouldn't some be stuck to that thing?
IF it were all gooped up with glue during the installation that is.
Maybe all the glue cracked off?
Here's a little secret about glue:
NO MATTER WHAT THEY SAY, ALL GLUE BREAKS DOWN EVENTUALLY.
If you help it along, it breaks down faster.
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Chiloe
Trad climber
Lee, NH
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The glue does not bond to the bolts. It bonds to the rock, and holds the bolt mechanically
(the reason for those glue grooves).
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graniteclimber
Trad climber
Nowhere
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Here is a post from the other forum:
"We used these directions installing the bolt Ushba
The shaft was sunk all the way into the hole.
I think the bolt was installed correctly.... but last Friday when we were attempting to install another, we noted that about a half inch of material could be removed from the surface of the ceiling with little effort.
What that means ( to me) is that it is possible that the bolt was sunk all the way to the shaft in Dec 2004, and over time, material near the hole fell of , exposing a half inch or more of the shaft.
This exposed shaft, then would be the brunt of stress. This could explain the bend seen in the photo.
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dirtineye
Trad climber
the south
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NO bonding to the bolt at all?
I guess that's why they want you to embed the eye a little.
ya know, I've seen epoxy used that did bond to the metal, on some glue-ins in NC.
Seems to me that if the glue does not bond to metal at all, then the rings should be something other than concentric rings.
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Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
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Dirt - That's correct. These adhesives are mainly used to secure rebar, threaded rod, ect
into concrete. It's the threads on the rebar or rod that keeps it secure. It does knott
stick well to metal (if at all). Later versions of the Tortuga (and most likely the bolt in
question if it was purchased in 2004) have notches in them to resist lateral movement.
FWIW, a couple of the Fixe stainless steel bolts that were installed at Mickey's Beach
also rotate a slight bit; those bolts have dimples in them to resist lateral movement.
More info (my post from 2005) here:
http://www.supertopo.com/climbing/thread.html?topic_id=117902&msg=118438#msg118438
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jfs
Trad climber
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OK, I never post here but something's bugging me about that picture of the bolt in situ on the roof.
In the original pic of the broken bolt, the bend is AWAY from the eye. But, if I am seeing the second (roof) pic correctly(and I may not be)...it looks like the eye is hanging "below" the shaft of the bolt. I can definitely see that the shaft is sticking out from the rock too far...but shouldn't the shaft be bent in the opposite direction based on how it appears to be installed?
To put it another way, the broken bolt is shaped like a lower case letter "q" but it seems like it should have bent into a lower case "g" based on the in situ picture.
Am I missing something?
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Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
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I've been thinking exactly the same thing. Let me repeat what I wrote in the 2nd post of this thread:
WTF?
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jfs
Trad climber
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That is unless...just to throw this out there and complicate things further...we are all seeing it wrong and it IS installed vertically (with the eye hanging on the right) and there's just some weird shading that makes it look like it's in at an angle. If you look closely it seems like this could be possible...???
Even if this is the case, the shaft is still exposed too much.
Potentially...years of rope dogging and lobbing off the hold outside the roof and swinging back and forth below...could have caused the stress needed? Especially if the choss broke off ONE side of the bolt only...exposing it to stress/bending in one direction only??? Or even if it was just 5 degrees off vertical???
Like HK said - a photo of the rock...
don't mind me...just trying to complicate things more. =)
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Chiloe
Trad climber
Lee, NH
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Here's a different photo posted on RC.com shortly after the bolt was first placed.
The way I read both this and the earlier photo, the eye is to the R, and the bolt itself
angled slightly up L (which would be consistent with the bend noted earlier).
Also, it sure looks like the shaft was already exposed.
Full context:
http://www.rockclimbing.com/photos/Sport/Hardware_was_approved.._47849.html
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graniteclimber
Trad climber
Nowhere
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The photo was added to rockclimbing.com on February 13, 2005 and the caption states the bolt was installed December 18, 2004, so it was already sticking out back then.
Larger version of the photo.
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JLP
Social climber
The internet
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" I don't think so. The bolt really should never have been loaded in the area of the groove/notch. That notch should be buried subsurface. "
The bolt is extremely weak compared to others on the market.
The glue will not prevent torsional nor tensile loading back to the ring feature.
The placement hole is larger than the bolt. Glue is soft. Therefore the bolt will bend somewhat in all cases.
Placement of the ring during the manf process may be yielding the metal, making it even weaker.
Loading the bolt in a laboratory and posting those #'s means very little.
I say the bolt is weak. I've decided I don't like it. If it were my design, I would change the ring feature.
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bwancy1
Trad climber
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This thread is awesome!
We have all read the posts regarding the disproportionally high number of climbers that are engineers, but who knew so many climbers are forensic metallurgists!?
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Chiloe
Trad climber
Lee, NH
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JLP:
The bolt is extremely weak compared to others on the market.
I claim no metallurgical expertise but ... how do you know this? Extremely weak compared to
what others on the market, in the warm marine environments for which the Tortuga bolt was designed?
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Brian in SLC
Social climber
Salt Lake City, UT
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Yeah, I don't know how you'd make a statement like that without knowing what the spec's on the Ti bolts were.
Speaking of which, the USHBA info on the net indicates its a special alloy? Anyone know what? Spec's?
Its a 10mm bolt with a fair amount of tensile strength, methinks. 120k or above?
-Brian in SLC
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