Drilling (continued)
4. A hole is drilled because rock is chipped by the concussion of the
bit from the blow of the hammer. Grip the steel firmly but not tightly
during each blow. Hand drilling produces very little shock in the 'steel-holding'
hand. The holder in a modified double jacking operation will also find
that only a small amount of shock is transmitted from the blow of the
hammer. Always wear gloves while holding, in case of a glancing blow.
After each stroke, turn the drill about 1/8-revolution; this is called
'shaking' the steel. Drill steel is usually octagonal in shape, so turn
the steel so the next flat side faces you. There is a slight recoil
of the steel after each blow, and it is after the recoil that shaking
is performed. Lift the steel slightly before turning. If the steel is
not turned, the bit will sink straight into the cut and jam in the hole.
When shaking, allow your grip to relax slightly after each rotation.
Regain your grip before the next blow.
Difficulty in shaking the steel, especially in 'down' holes, indicates
that the rock dust in the bottom interferes with the cutting edge of
the bit against the rock. With two hands turning the steel, teams may
go for longer periods before clearing cuttings from the hole. Water
is helpful for removing cuttings from holes.
5. Regularly add small amounts of water to minimize dust from drilling
and keep the drill steel cool and the temper intact. This keeps particles
in 'down' holes in solution so they won't hinder the progress of the
drill. Water creates a mud that sticks to the steel and is withdrawn
from the hole with the steel. The adhering mud is removed by rapping
the steel sharply against the rock. Holes are periodically flushed clean
by bouncing the steel in the hole while adding water to create an agitating
motion. The generous use of water allows the drilling action to force
cuttings out of the hole as quickly as they are generated. Minimize
unpleasant splashing by wrapping a small rag around the rod at the top
of the hole. Keep the rag loose so shaking is not impeded.
Using water in a drilled hole.
Removing cuttings from deep holes may require more water than is readily
available. In this case, small amounts of water may be used to create
the mud, and a long-handled spoon can extract it. Oldtime miner's spoons
were forged from various lengths of iron rod. They had a handle opposite
a flattened, slightly curved end approximately 3/ inches wide and up
to 6 inches long. These spoons were used for clearing holes of cuttings
and for retrieving sticks of powder from misfired holes. The pointed
tip on the handle end was used to thoroughly clean holes before loading
and to pack explosives in the holes. Today similar soft metal "powder
spoons", made of 3/8-inch iron rod in lengths up to 8 feet, are
sometimes still used in underground mines. We made a 30-inch long version
of the "powder spoon" for trail work. We also made a spoon
from a piece of aluminum tubing 1/2-inch in diameter and about 22 inches
long. We flattened and shaped one end so it had a flat edge roughly
perpendicular to the rod handle. This spoon worked well for cleaning
1'/-inch holes up to 16 inches deep.
Our version of the miner's powderspoon
had a
30 inch handle and a 6 inch spoon.
The aluminum spoon we made had a 22 inch
handle and a 5/8 inch spoon.
Drilling continued...
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