Chockstone Forum

      Sponsored By
      ROCK
   HARDWARE

Chockstone Photography

Australian Landscape Prints

Chockstone Forum - General Discussion

General Climbing Discussion

Topic Date User

Fixed gear guidelines in the Grampians 1-Jun-2018 At 7:49:05 AM uwhp510

Message

I've pulled a few tru-bolts. Sometimes they come pretty easily and sometimes its a bit of a pain. Got the technique off youtube. Its pretty clever really.

Take off the hanger, tap the bolt in to loosen it from its sleeve, put a washer next to the rock and put the nut back on, just snugish but not tight on the washer. Put another nut on and lock the two nuts together. Spin the bolt with a socket attachment in a drill on the locked together nuts whilst pouring a little bit of water on the bolt, for up to maybe a minute or even two. An impact driver probably works here as well. The screw action of the thread carries the water down to the back of the hole where it mixes with rock dust and makes an abrasive cutting compound. The abrasive allows the inner edge of the sleeve to wear a little step into the cone at the back of the bolt.

Next you need a puller which can either be made or bought. I made one from some high tensile M16 threaded rod, with an M10 sleeve nut welded to the end which goes inside some steam pipe. You thread the sleeve nut onto the bolt, put the steam pipe against the rock around the bolt and wind up the M16 nut until the bolt either comes out cleanly or sometimes snaps off the end of the cone. Sometimes you need to spin the bolt longer with more water to get the little step going. The youtube folk have opted for fancy and expensive hydraulic pullers which work even better.

I'd say that rust would probably make this technique harder/impossible, but that's just a guess since all the bolts I've done have been pretty new.

The end result is that the bolt comes out with only a hole left behind, which gets patched with epoxy and rock dust and basically disappears.