Using the Drill(click to enlarge)Once you've decided where to put your bolt, you have to actually physically place and set it. The methods used differ substantially depending on whether -you are using hand bolts (spits) or Hilti HKDS's.
+you are using hand bolts (spits) or drilling using Hang Fix anchors. -Before you actually start drilling, it is wise to flatten the surface of the -rock around the bolt site. This allows the hanger to lie flat against the rock. -
-Different types of hanger have different footprints. When dressing the rock, use the pointed -end of the hammer and tap gently, so as not to crack the rock below the -surface.
- - -List of people trained for installing hang fix anchors
+See the 2020 appraisal of anchors and choice of bolt types for future expos.
Using the Drill(click to enlarge)Since the first cordless hammer drills made an appearance on Expo 1990 -thanks to sponsorship from Bosch, drills have been enthusiastically adopted as -the best solution for large-scale bolting tasks; some of the fun and games of -recent years, like the 21-bolt traverse over Gaffered to the Walls in 2003, -would be unthinkable with hand bolts. However, drills are not suited to use -with ordinary spits, as the setting process depends critically on the bottom of -the hole being flat. It is possible to drill a hole part-way with a power drill -and finish it off by hand, but this is tedious.
+Hence we have found it easier to use Hilti anchors, which are specifically -designed for use in drilled holes.
-There are two versions of these bolts, the HKD and the HKDS. The latter are -easier to use, as they have a "shoulder" around the top of the bolt which sits -against the rock, meaning that the depth of the hole is not important.
- -To place a HKDS, drill the hole in the obvious manner until it is deep -enough for the bolt to sit in without touching the bottom. If in doubt, drill -it deep! When the hole is deep enough, grab a setting tool and start bashing it.
- -Start with very gentle taps. The reason for this is so the shoulder can hold -the bolt in position until it begins to grip the sides of the hole; if you -start by smashing it with all your might, the shoulder will bend and the bolt -will disappear, useless, into the depths of the hole. Once it has some grip you -can start hitting a bit harder.
- -It is very important to hit the Hilti setting tools exactly square, as they -are made of very hard steel which is rather brittle and hence it is easy to -shear the end off. When the bolt is fully set, you should be able to see marks -on the shoulder of the spit from the four little teeth on the collar of the -driver; don't worry if you can't see all four setting marks, but aim for two at -least - one can easily be a consequence of leaning the driver over too far to -one side.
- -Sometimes, in particularly hard rock, it can be impossible to get the -setting marks. Use your judgement; if you're not making any progress despite -sustained hammering, it's probably OK to stop!
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