Enlighten Me.
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Found bolts like this and others similar but with Metolius hangers. My knowledge of bolts in pretty limited but I know most of the time button-heads are questionable. Can someone enlighten me on what's going on here and possibly when this may have gone in? I was told about this crag by some old-timey locals and it seems like it's been a while since anyone has climbed here. The rock is granite and the location is in Southern California. |
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Well, the stainless hanger is in good shape. The non stainless bolt is corroded, of unknown strength and should not be trusted. Does that help? |
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I wonder why someone installed a nice stainless hanger with a carbon steel buttonhead. Seems like such a mismatch of good hanger- bad bolt. Such are the mysteries in the climbing world! |
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Greg D wrote: Well, the stainless hanger is in good shape. The non stainless bolt is corroded, of unknown strength and should not be trusted. Does that help? I figured the "should not be trusted" part. it's too bad because the rock climbs really well and the spacing of the bolts was done well. The anchors are similar but with rusty chains and a single quick link "master point" |
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TimFromMaine Dailey wrote: If you can do the moves without falling, you good to go! |
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That looks like a 5/16" buttonhead... if so it's the same effective diameter as most 3/8" sleeve bolts and thus pretty strong. Bolts I've seen (and replaced) like this were always much better than I expected, and those were in much more humid areas (NC). Not saying they're ideal but they're probably safe. Luckily these are super easy to pull and replace if the route is worthwhile. |
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A 5/16" buttonhead was the type of bolt that failed and contributed to Scott Sederstrom's death in Owens River Gorge (SuperTopo thread). The split-shaft bolts (aka button heads, aka compression bolts) can have small cracks introduced into the shaft during installation and over time corrosion exploits this and propagates the crack until the unknown day the bolt can no longer resist imparted loads and it fails. |
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FrankPS wrote: I wonder why someone installed a nice stainless hanger with a carbon steel buttonhead. Seems like such a mismatch of good hanger- bad bolt. Such are the mysteries in the climbing world! Probably because there were quite a few years when all comercially available hangers were stainless, and during those years, almost all bolts that were installed were plated bolts on a stainless hanger. To the OP, 5/16" buttonheads can be very strong, but as has been stated, they can also be very weak and have failed causing death, so be careful. |
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Here's the supertopo thread where they discuss the accident and it has pictures of the bolt that broke. Pretty scary given that the head of the bolt looks fine but the inside (where it broke) is entirely rusted through. |
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Yea, no telling what the condition is inside. Sometimes they are easily broken, other times a complete PITA to remove and very strong and nothing on the outside predicts one or the other. |
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You need to acquire a tuning fork that is wide enough for the 5/16. |
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Timothy Fisher wrote: You need to acquire a tuning fork that is wide enough for the 5/16. Anyone make and sell tuning forks? I need one but im too lazy to make one. |
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Tradiban wrote: And too lazy to Google it, too. http://lmgtfy.com/?q=buy+tuning+fork |
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FrankPS wrote: Im a busy man, can you be a peach and google that for me? |
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ASCA currently has a long wait list for tuning forks so I'm having a go at grinding a few myself, but it's slow going with a dremel. The same wall has a 1/4 inch threaded rawl split shaft that I might try and pull first. The climbs are quality, just forgotten. |
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I can mill a few, shoot me a PM. Just cover the shipping costs and cost for the materials. |
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Greg Kuchyt wrote: I can mill a few, shoot me a PM. Just cover the shipping costs and cost for the materials. Try a band saw? I have one of those. |
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Tradiban wrote: That would probably work but ultimately would depend on what you're trying to cut. If you're trying to cut the tile chisels to make some of the thinner profile tuning forks you may have less luck. Those are hardened tool steel (I think 50-55 HRC when I tested with a file set) and the initial cut is a small cross section causing a high tooth load. You're more likely to start breaking teeth on your saw blade. Ideally you want a few teeth simultaneously engaged to get the set of the blade to track properly and prevent overloading a single tooth. |
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I've cut hardened steel with a 10" fiber cut-off blade mounted on my Shopsmith. It's essentially a table saw that I can slow down to ~300 rpm. You could probably rig up a similar thing with a drill, a vise, some clamps and a board with a slot in it. Spritz with water to keep the heat down. |
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Gregger Man wrote: I've cut hardened steel with a 10" fiber cut-off blade mounted on my Shopsmith. It's essentially a table saw that I can slow down to ~300 rpm. You could probably rig up a similar thing with a drill, a vise, some clamps and a board with a slot in it. Spritz with water to keep the heat down. Like an aluminum oxide resin wheel? 300 RPM seems super lower, like an order of magnitude low. Do you see a huge amount of wheel wear at 300 RPM? Grinders and chop saws are all like 3k RPM and most cut-off wheels are rated up to like 5-6k. |
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I've just gone slow in order to keep the heat down. |