Drill Bits

The Different Types of Drill Bits and their Uses

Drill Bits are used in drilling machines commonly referred to simply as "drills" to make cylindrical or non-cylindrical holes. Different types are available for drilling into different materials. For example, a masonry bit is used to make a hole in bricks, cinder blocks or mortar.

At the opposite end of the cutting edge is the shank. The shank fits into a chuck, which can be loosened for changing or tightened for drilling. The shank can have an effect on the centering accuracy or the torque of the bit.

In most cases, shanks are categorized according to their shape. For example, you will find triangle, straight, square, round and hex shapes. The Morse taper and SDS shanks are used for special purposes.

For example, the SDS shanks have hammer-like piston action that makes them especially suitable for drilling wiring or plumbing in existing brick or stone buildings. Most shanks used for non-industrial purposes are straight, rather than tapered.



For the do-it-yourselfer, wood is one of the most common materials used. One of the Drill Bits designed specifically for drilling into wood is called the "lip and spur". Other names include brad point and dowelling bit.

The twist bit design, which is the one most often used for working with metal, has a tendency to wander back and forth, when it first encounters the flat surface. In metalwork a smaller pilot hole is typically drilled to prevent the surface from being scratched and to ensure that the hole is drilled in the proper place.



In wood, the lip and spur bit can be used instead of drilling a smaller pilot hole. Instead of having a chisel point, as is found in twist designs, the lip and spur bit has a central spur with a sharp point and four sharp corners to cut into the wood. The sharp points push into the softer wood, keeping the bit from wobbling and ensuring proper alignment.

One of the bits that you may see when you are shopping for tools is the spade bit. It is used for rough boring in wood. The spade bit has a flat piece with a sharp centering point and two cutters. It may be used to cut a hole through a board to allow for a wire to be run through it.

Other less commonly used Drill Bits include the spoon bit, the Forstner bit, the step bit and the center bit. Each bit comes in an assortment of diameters, measured in metric or inches. In order to have the right diameter on hand, most people keep a set of twist or lip and spur on their workbench.

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