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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Nov 28, 2010 - 08:03pm PT
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I did another test today because I fear we might be comparing apples to oranges. I sheared a 1/4" x 1-3/4” 316 SS wedge bolt with the same fixture I used for the 1/4 x 1-1/2 button head. I did this because the button head was tested with thick piece of angle (0.200") that I had switched to because the tests kept destroying the loading piece. If you look at the last button head test you can see that the shank near the head deformed in double curvature or an "S" shape because the thicker loading piece kept the head from rotating
This was not the case for the earlier 14" SS bolt where the nut rotated a bit.
Here is the latest test
Score so far:
1/4 x 1-3/4 316 SS wedge bolt
3460 pounds tension
3000 pounds shear
1/4 x 1-1/2 button head
1860 pounds tension
3340 pounds shear
I think as a back country anchor, I would pick the wedge bolt since it will last nearly forever. The fact that it cannot be removed might be a benefit or a deficit depending on how you look at it. I feel that the button heads are too susceptible to degradation due to corrosion or mechanical damage to either the steel or the rock. If the wedgie gets loose, it will simply tighten up again. If the button head gets loose, it is useless. Once a split shank is compressed, it is permanently deformed it cannot expand. The wedge bolt expands whereas the split shank contracts which is why the wedge bolt is so much better in tension.
Could the opposite of expand be despand or dispand?
Also, I hand drilled the hole for the SS bolt with a standard 1/4" carbide bit. After I drilled the hole I slid the 17/64" HSS drill into the hole and it fit fine. I think the two holes were about the same diameter.
Also, I triple checked calibration by comparing (hydraulic pressure) x (specified cylinder area) to measured load getting less than 1% difference.
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mucci
Trad climber
The pitch of Bagalaar above you
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Nov 28, 2010 - 08:35pm PT
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"Once a split shank is compressed, it is permanently deformed it cannot expand"
Once a split shaft is compressed it is in "Tension Mode". That design (split shaft) is meant to increase tension. The steel has memory that does not dissapear as soon as it is placed, rather the tension is in working mode until a change in the placement medium (weathering, water, high work load etc)
I find it very hard for one to lobby for a nonremoveable bolt in the backcountry. A simple button head for the FA, and a responsible future party with a tuning fork and drill can maintain a sustainable hole count.
The routes that these wedge bolts are in contention for are rarely done and should be treated as so during a subsequent ascent.
If I don't like a bolt's condition during an ascent, I have the right to replace using the existing hole.
Not a big deal with modern routes, but I have and will continue to bring a drill and do upgrades on any routes where my safety is comprimised by the condition of a bolt.
How many are in the same boat?
Thanks for the testing BAnQ, lots of good info here.
Mucci
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Nov 28, 2010 - 09:49pm PT
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Mucci, how ya been?
Perhaps you can explain what you mean by "Tension Mode" but here's what I see. When I pulled the button head out, it was permanently compressed and looked like this:
Measuring it is a bit crude but it looks like it would just about fit into a 0.28" hole barely touching the sides after being compressed in the tension test hole. (the straight shank part is about 0.24")
When I measure hand drilled 1/4" holes, they come out closer to 0.26" - 0.27" so the split shank might be expected to have 2/100ths of an inch of bite but probably less since it actually enlarges the hole when it goes in. If asked under oath, I would say my best estimate is that a newly placed button head has about 1/100th inch of elastic compression or bite - not much to hang your life on. Over time, that can only decrease due to weather and corrosion. Also, mechanical damage due to rock fall or ice fall knocking on the hanger might loosen it. Any wiggle such as clipping it and hanging on it can only weaken it. Pretty much anything will reduce the strength while only replacing it can increase the strength.
So, yes, very good for first ascent but I think questionable for second. On the other hand, the 316 SS bolt is probably good, with basically unchanged strength, for many, many years.
According to the last page of this paper:
http://www.safeclimbing.org/education/Heavy_Climbers_Beware.pdf
A 300 lb climber has to take a 4.8m, factor 1.7 fall to generate 13.3 kN (3000 lb) impact. If there is any chance that an anchor will be exposed to anything like that, I would place a 3/8" bolt anyway. I wouldn't place a 1/4" anything on a route I thought might get a lot of traffic.
Anyway, the very few bolts I've ever placed were 3/8"
Just my opinions, I hope others have their opinions and will explain them to us.
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mucci
Trad climber
The pitch of Bagalaar above you
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Nov 28, 2010 - 10:12pm PT
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1800+ lbs of pullout with 1/100th of an inch tension?
Sounds pretty good to me.
Tension Mode would be the "in situ" split shaft. Maybe the wrong term?
The metal is tensioned due to memory, why else would there be a split?
Of course I am not a machinist and actually know very little about metal. It just seems as though the design trait of the split shaft is tension.
Why is the pullout so high if the tension is so low?
Thanks for info Banq, it has been very interesting to see your work on all of these bolts!
Mucci
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Fritz
Trad climber
Choss Creek, ID
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Nov 28, 2010 - 10:13pm PT
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Banquo: It is great that you are willing to put so much work & expense into doing this testing.
I haven't placed a 1/4" buttonhead on lead since about 1979, but it very good to see all this wonderful information.
It gives me more, or sometimes less, confidence in some of the old stuff the old me finds on lead in Idaho.
Thank you! Fritz
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Thorgon
Big Wall climber
Sedro Woolley, WA
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Nov 28, 2010 - 11:38pm PT
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Banquo,
What Fritz said, thanks for your tireless efforts!
Thor
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speelyei
Trad climber
Mohave County Arizona
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Jan 15, 2014 - 09:33pm PT
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BBST
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Steve Grossman
Trad climber
Seattle, WA
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Jan 15, 2014 - 11:45pm PT
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Greg- You guys have pulled thousands of 1/4" split shaft Rawlbolts.
How many of them have a corroded break at the top of split especially the ones that come out easily?
I walked away from 3/8" X 2 1/2" split shafts when I cleaned one off of El Cap with two blows exposing an 80% corroded face on both sides of the split.
I have placed hundreds of them on lead thinking I was doing the right thing for the long haul. If one of my bolts fails on you it won't be pretty since I tend to spread them out.
Tortured metal makes for poor anchors in the LONG RUN so if you are going to drill and not come back then don't use mild steel split shafts.
Initially they are good and reasonably strong but they don't stay that way.
Ed Leeper wrote an article confirming the unreliable nature of split shaft bolts including the 3/8" variety that I came across in my research too late to heed his advice and switch to stainless 5 piece anchors.
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Greg Barnes
climber
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Jan 16, 2014 - 02:02am PT
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Steve, I don't see that many snapped buttonheads - once you use tuning forks instead of prying, they tend not to snap. But it depends on the climate - for instance Tuolumne buttonheads nearly always pull easily (freeze-thaw) while rusted Valley buttonheads are more likely to snap. The more rusting, the more likely to break.
When they do snap, seems like it's typically at the top of the split. I've seen it higher up (base of the hanger) as well, and every once in a while halfway down the split.
I think 3/8" buttonheads tended to require more "sledge-hammering" to place in hard rock, and so might be more likely to have damage incurred during placement. I haven't pulled many of those (especially if you don't count softer rock areas where those 3/8" buttonheads were not compressed - Pinnacles, Red Rocks, Joshua Tree), but they often just seemed smashed up. I hope that your experience with them failing easily is not representative of most of them, because a fair number of those bolts are out there, from local cragging like Castle Rock State Park to multipitch areas like the Needles (I think Greg Vernon used those for replacement, sometimes with those Altus titanium hangers).
Do you have a copy or a link to Ed Leeper's article on buttonheads?
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Roger Brown
climber
Oceano, California
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Jan 16, 2014 - 07:45am PT
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Steve,
I agree with Greg. We have gotten better at pulling them. Even if cracked. we are getting better at getting them out in one piece. I have a feeling that the cracked ones were damaged during placement. I have almost every bolt that I ever pulled so maybe when I get old I will do a little research. I believe everything goes back to the hole. Power drilled hole in super hard rock may have a lot to do with it. I have been pulling a lot of 5/16 lately and have yet to find a cracked one, but that is a whole different mystery.
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Steve Grossman
Trad climber
Seattle, WA
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Jan 16, 2014 - 11:30am PT
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Greg and Roger,
Thanks for the response. I will try and find the Ed Leeper article to post but it may take a little time as I didn't scan it initially.
I would hate to see folks going back to this kind of anchor based on the testing and discussion here. The 3/8" split shaft Rawls that I used and the one that turned me away from this type of anchor are the threaded variety. A couple of rebolting accounts have mentioned shearing while trying to refit 3/8" studs with new hangers since you didn't have the means available to pull them out. I suspect that the portion remaining in the hole likely showed considerable corrosion.
I have used 1/4" button and bevel headed split shaft bolts on walls in aid applications. I have also had problems with the tempering on one batch of button heads that made them buckle on the way in. I stopped placing skinny bolts on free climbs very early on in my climbing career.
Take a look at the top of the split for a stress fracture line if you want to examine some of your pulled bolts with a magnifying glass.
Is the ASCA even considering using these? I hope not.
Cheers,
Steve Grossman
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Greg Barnes
climber
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Jan 16, 2014 - 11:56am PT
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Hi Steve,
No we are DEFINITELY not suggesting or using 3/8" split shafts! Besides we only use stainless steel bolts (except rare cases with big bolts in soft desert sandstone) and 3/8" split shafts are not made in stainless.
We do still supply the 1/4" split shafts for (no hanger) rivet replacement on aid routes. We encourage using Bryan Law's two washer idea for those, that way the second washer will help prevent rock damage when the 1/4" is replaced in the future.
Even if the bolts were always super strong, it's very hard to remove bigger split shafts without damaging the rock.
Greg
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Steve Grossman
Trad climber
Seattle, WA
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Jan 16, 2014 - 12:16pm PT
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Greg- A suggestion if you are trying to extract 3/8" split shaft studs.
Get a cordless die grinder set up with a thin cutting disk so that you are able to cut through one side of the split once you have eased the stud out to the point that this is possible. Most 3/8" studs have been placed such that the split point isn't very far below the rock surface. If the whole show fails after your cut then you can use a punch and push the remainder back in and patch the hole.
I have loads of these to replace. Sigh...
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jonnywoodward
climber
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Jan 17, 2014 - 01:46am PT
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Anyone clipping one of those old 1/4 inch split shaft bolts (they were called Rawl Drive bolts) should be very, very scared if it is providing essential protection.
After removing probably in the region of 800 of these I can attest that one has no idea what one is clipped into. While some of them are a bugger to get out, and would hold Arnold on a full pitch whip, some of them come out after a few light taps of the hammer on the pin, and at Josh a number of them were pulled out by hand with no tools at all. Your two year old daughter could get some of these things out. Additionally about 1 in 8 come out of the hole with a rusted fracture on one end of the shear (split), evidence that the structural integrity of the bolt was substantially compromised at some point during its life in the hole. The fractures seem to be divided pretty evenly between the two locations, and usually mark a bolt which was easy to pull out. Almost all the bolts I have exprience with date from the 70s and early 80s, and were removed over the last 10 years. If you are still placing these bolts, you are placing time bombs with the clock set to random. Whether that's OK or not is a matter of opinion.
In case you were wondering, about 780 of those 800 were actually replaced.
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Mungeclimber
Trad climber
Nothing creative to say
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Jan 17, 2014 - 03:20am PT
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In case you were wondering, about 780 of those 800 were actually replaced.
That's a lot of replacing. Thx!
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Steve Grossman
Trad climber
Seattle, WA
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Jan 17, 2014 - 10:52am PT
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At last, a light in the forest.
Thanks JW!
I get really tired of repeating myself on this issue.
Good on you for your extensive replacement work.
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bhilden
Trad climber
Mountain View, CA/Boulder, CO
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Jan 17, 2014 - 02:04pm PT
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I have seen the same thing as Jonny with respect to broken shafts of 1/4" split shaft bolts.
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henny
Social climber
The Past
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Jan 17, 2014 - 05:33pm PT
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The worst case of breakage that I've seen on a 1/4" split shaft was the bolt at the top of the dihedral on the second pitch of the Iron Cross at Suicide. A single light tap to start driving a pin under the hanger popped the bolt out. It had completely broken through both splits of the shaft, leaving all of the bolt from the start of the shaft split onwards in the hole. The rust and corrosive build up completely covered the broken end of the bolt, indicating that it had not "finished" breaking due to removal.
The bolt visually looked fine, but what a surprise lurked inside the hole.
Like Woodward said, you never know what you're getting with old 1/4" bolts. It isn't all that uncommon to see cases where half the shaft is broken when removing them.
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Steve Grossman
Trad climber
Seattle, WA
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Jan 17, 2014 - 07:40pm PT
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Once I locate the Ed Leeper article I will start a thread so that folks stop placing these bolts as permanent anchors when they suck for the long haul.
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