A spade bit is a type of drill bit used for boring large holes into wooden objects. These bits consist of a long, thin rod known as a shank. One end of the shank is inserted into a drill during use. The other end is flat, with a small point projecting out at the end. Between this point are two cutting edges, which are used to cut a cylindrical opening in wood as the bit rotates in the drill.
These bits are available in a wide variety of sizes, and can be used to drill a range of hole sizes. Depending on the quality of the bit being used, it may be necessary to drill a pilot hole in the wood before using the spade bit. This hole is created using a traditional spiral drill bit, and is placed directly in the center of the planned hole. The pilot hole helps direct the pointed tip of the spade bit, holding it steady to increase the accuracy of a cut.
Some modern spade bits have a threaded tip at then end, similar to a screw. These units are known as self-feeding bits, and often eliminate the need for pilot holes. A self-feeding bit will generally be more expensive than a regular spade bit, but will greatly improve the speed and accuracy of the cuts.
Several other types of tools can be used as an alternative to these spade bits. A hole saw is the most common, and is used to make fast, clean cuts. Auger bits can also be used to cut holes. While they are slower than spade bits, auger bits are also more accurate and precise, though they may not work on harder wood species. To cut very large holes in wood, such as those required for pipes, a multi-spur bit can be used.
One of the primary benefits to spade bits is that they can be easily filed down to create custom-sized holes. Because they are so affordable, most users will simply use a metal file to sand the edges of the bit down to the desired size. These bits are also easy for inexperienced users, and are one of the most basic tools for cutting holes in wood doors, furnishings, and many other applications.