A Porter-Cable sander is one of a number of different power sanding machines, some hand-held and some stationary, made by the Porter-Cable company. Used primarily for woodworking and carpentry applications, each Porter-Cable sander is designed to meet a specific need. Specifically, Porter-Cable manufactures power belt sanders, stationary belt sanders, disc sanders, hand-held belt sanders, random orbit sanders, and finishing sanders.
Founded in 1906, the Porter-Cable Company began making power woodworking tools in 1914. In 1926, its chief engineer invented the power belt sander. This Porter-Cable sander, which consists of a cloth belt with an abrasive surface stretched over and between two rotating cylinders, revolutionized the power tool industry. When the tool is energized, the cylinders rotate and the belt revolves around them, very quickly removing excess wood from a workpiece. Some belt sanders are stationary, mounted on a workbench, and the workpiece is held to the revolving sanding belt. Larger projects, such as tabletops, are more easily sanded with a hand-held belt sander. Designed for rapid removal of wood from a workpiece, belt sanders are generally used only in the initial stages of a project and not for finishing work. That is, they are not designed for bringing a piece to the final level of smoothness suitable for applying a finish.
Some of Porter-Cable's stationary belt sanders also have a disc sander installed as part of the same tool. A disc sander is a smooth disc to which an abrasive disc is affixed. When turned on, the disk spins rapidly, turning many thousands of rotations per minute. It's not as aggressive in stock removal as the belt sander, and once a piece has been initially smoothed on a stationary belt sander, it can be smoothed more finely on the disc sander.
Porter-Cable manufactures hand-held belt sanders as well. While they provide a much greater degree of flexibility than the stationary models offer, they sacrifice some stability. While the aggressive nature of belt sanders can lead to errors and ruined workpieces, it's easier to make a mistake with a hand-held belt sander than with a stationary model. Nevertheless, the hand-held belt sander is the most popular Porter-Cable sander.
Porter-Cable also makes random orbit sanders and finishing sanders. Random orbit sanders look like hand-held disc sanders, but have a very different fuction. Unlike the disc sander, whose disk spins at a high rate of speed, the disc on a random orbit sander makes tiny movements on two separate axes, and is generally considered preferable for finer work. Many woodworkers will use a random orbit sander as a finishing sander. The other Porter-Cable sander, the finishing sander, is sometimes called a palm sander because it's designed to be held in the palm of the hand. These sanders accept a very fine abrasive surface, and are meant to be the last tool used before the finish is applied.