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| Messages 1 - 9 of total 9 in this topic |
Big Joe
Trad climber
Denver, CO
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Topic Author's Original Post - May 16, 2015 - 03:19pm PT
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Want to buy new Mammut ring bolts. Developing a drill jig to remove them and need new ones for test rock in garage.
Ring bolts look like below.
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Big Joe
Trad climber
Denver, CO
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Topic Author's Reply - May 17, 2015 - 09:58am PT
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bump
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Big Joe
Trad climber
Denver, CO
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Topic Author's Reply - May 18, 2015 - 07:30am PT
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bump
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Big Joe
Trad climber
Denver, CO
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Topic Author's Reply - May 19, 2015 - 06:29am PT
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bump
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Steve Grossman
Trad climber
Seattle, WA
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May 19, 2015 - 09:19am PT
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You aren't going to have much luck sourcing this style of bolt as they never really caught on over here.
Where are you climbing that you need to service this type of anchor?
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bhilden
Trad climber
Mountain View, CA/Boulder, CO
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May 19, 2015 - 09:33am PT
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Some Boulder-types with Euro-climbing experience back in the 1980's(Christian Griffiths, etc.) used these on some hard routes in Eldorado Canyon (Paris Girls, Rainbow Wall, etc.) and Boulder Canyon(The Verve, etc.).
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Greg Barnes
climber
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May 19, 2015 - 09:36am PT
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Unfortunately there are quite a few around Boulder.
Just heard from Jim Titt that they were not common in Europe either, and he doesn't know of any way to find some.
A handful in Tuolumne, I've also seen them in Red Rocks, and there are some on El Cap. Here's an old thread on them that I started in 2003. Unfortunately I never did learn how to remove them, particularly in no-power-tools-allowed Wilderness areas:
http://www.supertopo.com/climbing/thread.php?topic_id=15905&tn=0&mr=0
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Steve Grossman
Trad climber
Seattle, WA
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May 19, 2015 - 10:11am PT
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A fundamentally poor design, IMO.
Bummer that they are plentiful.
If you removed the ring and drilled a 5/16" hole to reach the central cavity the you could easily thread the outer portion of the hole (using a short tap) enough to use a hardened machine bolt (with the threads ground away from the very end to avoid binding) to separate the cone from the shield which is your primary goal if you want to avoid a ugly crater.
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Big Joe
Trad climber
Denver, CO
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Topic Author's Reply - May 23, 2015 - 08:14am PT
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Thanks to all those that responded so far. There are ~100 or so of these ring bolts on routes in the Boulder, CO area. Probably north of 200 if you include the South Platte and other local areas in the vicinity of Boulder. They were popular with equippers for a span of about 3 years from 1988-1991 in the Boulder, CO area.
In general ring bolts are either bomber or duds. If the hole depth was over drilled on install they are duds and can be funked out easily. The rings are also a PITA to clip as they tend to get hung up at odd angles.
They can be removed with a long pry bar (i.e., 4'+ variety) inserted through the ring and rotating the bolt body. In softer stone (e.g., Fountain Sandstone) this works about 50% of the time but you risk damaging the rock. Success rates with this method diminish in harder stone like granite.
I have also tried a hydraulic punch to pull ring bolts out directly with massive force. Removal success rate is ~5% as the ring will often break or worse the rock is badly damaged during extraction (FYI - done on test rocks at a quarry).
Core drilling is another option but leaves a hole so large not even Jim Titt's 16mm bolts can fill it.
Lastly there is center drilling with 5/16" bit. You have to drill out the cone as the bolt body is too soft for a tap and thread method Steve suggested.
I am in the midst of building out a drill jig to ensure center drill.
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| Messages 1 - 9 of total 9 in this topic |
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