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Screwbolts? any good or certain death? 30-Nov-2010 At 1:29:55 PM Tommo

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I have placed these exact screwbolts in blueys sandstone earlier this year. I have also placed some 12mmx100mm. In all cases they were temporary placements, due to non-stainless. A couple were placed singly as back-up for suspect natural anchors during investigative rapping. In one case I placed them on lead, during the FA of Bewilderbeast, at lower Pole 28. I was hanging on sky hooks, using a power-drill I pulled up on a tag line. They seemed like the obvious choice for placing on lead when I needed a bolt to protect me immediately (which rules out glue-ins) but also something easily removable so that when I replaced them with the glue-ins (at a later date, with incredible shenanigans setting up and executing an overhung rap-in from above - the reason for the original bolting on lead) I could remove them easily (10 seconds) and have a usable hole for one leg of my u-bolt or for a ring. All were placed with a PFH key-hole hanger, but screwed tight squeezing the hanger against the rock. I didn't whip onto any, but did load them on rappel. They are so bomber. BUT I did notice they were too easy to remove, in that you only had to turn them barely a fraction with the socket, and they would unscrew by finger with almost no resistance. So my guess is they are super strong, but will not handle the repeated loads very well. After they have been removed once, you can see the thread carved into the walls of the hole (probably awesome for glue adhesion) but the 'fins' of rock making up the thread pattern were very fragile - screwing the bolt in the same hole a second time damages these fins easily. A somewhat irrelevant issue (removing and replacing the screwbolt multiple times) but it did make me wonder how strong these thin 'fins' would be when the bolt is loaded in tension. I thing depth (length of bolt/thread) is important with these. ie. long is good.

As for recessing ring-bolts (I think Neil mentioned this), I keep seeing more and more rings here in the US that are not recessed at all. And it freaks me out. Seems like it is not a major point to be taught here, and even doesn't mention it in a Climbing magazine/ASCA bolting guide. What's the deal?