A drill bit is a long, generally cylindrical object that is used together with a drill to create holes in a vast array of materials, for many different purposes. One end of the drill bit is the head, or drilling end. This end typically has a point on it and contains channels, called flutes, that are able to cut into various materials in order to drill a hole. The other end is the drill bit shank. It has no cutting surfaces but instead is made to be gripped securely by the chuck, the gripping part of a drill.
There are many different styles of the drill bit shank. One of the most commonly seen types, especially in the United States, is simply a smooth, straight shaft that is an extension of the head, without any flutes for cutting. Modern drills used for home maintenance and repair most often have this type of drill bit shank. It fits into the triangular-shaped opening of a triple-jawed chuck. When the chuck is tightened properly, the smooth shank will have minimal slippage during use.
A drill bit shank with multiple flat surfaces is also common, including the hexagonal shank. These are typically found in industrial applications. In some cases the shape of the shank can affect the accuracy of the drill bit. The brace shank, for example, may be used when exact hole placement and size is not critical, and it has the advantage of being easy to make as well as highly resistant to slipping while in use.
Another style of drill bit shank is called the SDS shank, for the German terms "Steck – Dreh – Sitz,” which translates in English to “insert – twist – stay.” The advantage of the SDS bit is that it is easy to use and changes out quickly. On the other hand, it can only be used with a drill that has the SDS chuck and is relatively expensive to manufacture.
Drill bits come in a wide range of sizes so that they can be used for virtually any job. They are readily available in a range of both metric and U.S. standard sizes. The drill bit shank on a very small bit may be larger than the rest of it, so that it will fit a standard drill chuck. Very large bits will often have a drill bit shank that is smaller, for the same reason.
