A hand drill bit is used with a hand-powered drill, commonly called a brace. A distinctive feature of the hand drill bit is the tapered, square shank that fits into the brace's chuck. Another feature of a hand drill bit is that most of them are designed exclusively to drill wood. The speed of the hand-powered brace is typically insufficient for drilling through steel.
Many of the hand drill bit designs are what are known as auger bits. This style of hand drill bit uses a threaded center point to assist in pulling the drill bit into the wood. The auger drill bit can be a single- or double-spur design. The spur is a small protrusion at the bottom edge of the drill bit, adjacent the threaded point, that actually scribes the hole before the cutting edge of the drill bit contacts the wood. This cuts the fibers in the wood and aids in producing a smooth hole in the wood.
An auger bit is named after the auger-type design of the drill bit. Large, auger-like twists are designed to carry wood chips up and out of the hole as the drill bit spins. By channeling the wood chips out of the hole, the bit is allowed to make a much smoother bore. The spur or spurs, as the case may be, not only scribe a hole as the bit enters the wood, they scribe a hole as the bit exits the hole as well, cutting the wood fibers and eliminating splinters around the edge of the hole. The wide sides of the auger drill bit aid in keeping the drill bit perpendicular to the wood as the hole is being drilled.
The high quality of the steel used in the creation of a hand drill bit commonly allows for the bit to be resharpened several times during the drill bit's lifetime. One area of the hand drill bit that cannot be easily repaired or replaced is the center screw point. This is a crucial component of the hand drill bit and is instrumental in keeping the drill bit in the proper location when beginning the hole. The design of the brace is such that it causes the drill bit to wander all over the wood as the operator moves his or her hand while attempting to drill the wood. The screw point allows the operator to position the point on the spot to be drilled, and the bit will not move as the brace is cranked.
