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.
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.
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!