What Is the Difference Between Drill Bits?

Twist Bits

• The most common configuration of drill bits for general applications is the twist drill bit. The shaft of the bit has a continuous groove that twists around from top to bottom. The tip of the bit features a point that serves to keep the bit centered at start-up. Less expensive bits contain less costly metals but are sufficient for light use. Black steel or chrome bits are capable of cutting wood, plastic and light metals.

High-Speed Steel

• Boring through sterner stuff on a regular basis requires better twist bits. Pneumatic drills achieve high rotating speeds to cut thick metal. Attempts to use cheaper bits in this application usually dulls the bits in short order, with minimal results. Specially constructed bits are coated with titanium nitride and have a golden appearance. The metal alloys employed in the base structure withstands heat, and the coating extends the useful life of the bit many times over.

Masonry

• Masonry drill bits bore into cement, brick and block. The tip of a masonry bit has a fluted, chisel shape that breaks through the material. An exaggerated twist groove helps to evacuate material out of the hole for faster cutting. Masonry bits perform best when used with a hammer-drill. The arbor of a hammer-drill moves in and out slightly while rotating, creating a pounding effect that takes full advantage of the chisel-shaped bit tip.

Specialty Bits

• Some specialty designs are intended for different kinds of woodworking projects, like counter-sinking. The bit drills a hole of particular length to accommodate a fastener and graduates in diameter to widen the top of the hole to accept the fastener head. Another example of a stepped-bit is conical in shape and allows progression in hole size by continued drilling. Drill bits of extended lengths are designed to reach tight spaces or bore holes to a specific depth.