DRILLS
Early man had the necessary skill and tools to drill wood, bone and
rocks. Exactly when this skill was developed and the type of drill that
was first used is controversial. Archaeologists find many items, which
were drilled; some of these had holes no more than 1/8 inch in diameter
and up to 6 inches in length. Excluding the stick drill turned between
the hands, there are two basic types of drills - the bow drill and the
pump drill.
The bow drill consists of a "bow", a drill stem, and a drill bit.
Depending on the task at hand, the bit was either wood or stone.
The wood bit was used to drill in rocks and to start fires. To drill in
stone, a wood bit was used. When the bit was a piece of cane, the bit
was filled with sand, which served as grit to drill through the rock.
For very small holes, a piece of hard wood was probably used and the
grit was placed on the wood tip. To drill through wood or bone a stone
bit was fastened to a wood shaft, which fitted on the drill stem.
Drilling was accomplished by twisting the bowstring around the drill
stem and the index finger. The finger twists served to tighten the
bowstring and make the drill stem rotate. The bow was moved in a
“sawing” action to cause the drill stem to rotate at an appropriate
speed. Pressure was regulated by a piece of rock (or wood) held on top
of the drill stem. This also served to prevent friction burns to the
hand pushing down on the drill stem.
The pump drill consisted of a drill stem with counter weights, a
straight "bow" with a hole slightly larger than the drill stem in the
center, and drill bits similar to those used with the bow drill. The
drill stem had a notch in the top end opposite the bit. The bow was
slipped over the drill stem, the string was placed over the notch and
the drill was rotated to wind the string onto the drill stem, and then,
by forcing the bow down, the drill would turn. Pressure was regulated
by the amount of “push” on the bow.
Roger L. Briggs
September 2000