A belt sander is a machine used to sand down wood and other materials for finishing purposes. It consists of an electrical motor that turns a pair of drums on which a seamless loop of sandpaper is mounted. Belt sanders can be either hand-held, where the sander is moved over the material, or stationary (fixed), where the material is moved to the sanding belt. Stationary belt sanders are sometimes mounted on a work bench, in which case they are called bench sanders. Stationary belt sanders are often combined with a disc sander.
Belt sanders can have a very aggressive action on wood and are normally used only for the beginning stages of the sanding process, or used to rapidly remove material. Sometimes they are also used for removing paints or finishes from wood. Fitted with fine grit sand paper, a belt sander can be used to assure a completely smooth surface.
Stationary belt sanders are used for removing non-ferrous metals, such as aluminum. Non-ferrous metals tend to clog grinding wheels, quickly making them useless for grinding soft metals, while belt sanders continue to grind without clogging. This is because the small grooves in the sand paper are opened up as they go around the arc of the drive wheel.
Belt sanders can vary in size from the small hand-held unit shown in the illustration to units wide enough to sand a full 4-by-8 foot sheet of plywood in a manufacturing plant. Some belt sanders can be as tall as 1.2 metres and 70 centimetres long.
Sanding wood produces a large amount of sawdust. Therefore, belt sanders employed in woodworking are usually equipped with some type of dust collection system. It may be as simple as a cloth filter bag attached to a portable sander or a large vacuum system to suck dust particles away into a central collector.
Belt sanders were one of the first power tools used in the growing field of power tool drag racing wherein a pair of stock or modified belt sanders are placed in parallel wooden channels and fitted with long extension cords. Each heat begins when a common switch or individual switches triggered by the racers energizes them, causing the sanders to race towards the end of the track spitting wood dust along the way. Stock sanders race down a 50' long track, while modified sanders race on a 75' long track.