A pad sander is a specialized hand-held power tool used by woodworkers to smooth the surface of wood, usually on a small project or a portion of a larger project. This type of sander employs a small piece of fine sandpaper, and is used for detail and finishing work. Many pad sanders can easily sand into restricted areas like tight corners, and can also sand uneven surfaces like chair legs or handrails. Variations in pad sanders include the size and shape of the pad, the type of sanding medium employed, the way the sanding medium is attached to the sander, and the type of powered motion employed.
One of the traditional methods of finishing wood to a smooth surface is sandpaper. Using sandpaper on its own will produce a smooth surface, but it generally won't be flat. To create a smooth, flat surface, sandpaper can be glued or nailed to a block of wood or hard rubber. With the advent of power tools, the electric sander became a staple of most home and professional woodworking shops in many different manifestations.
The "pad" in a pad sander is a square, rectangular, round, or other-shaped sheet of hard rubber adhered to the metal plate of the machine, which is attached to the motor. The sanding medium, either cut by the user from regular sheets of sandpaper or custom-made to match the particular sander, is adhered to the pad either by pressure clamps, double-sided adhesive tape, or hook-and-loop technology. In some cases, the pad will have holes in it so that the dust created in the sanding process can be vacuumed in and stored in a dust collection bag attached to the sander. There will be holes cut in the sandpaper attachment that should be lined up with the holes in the pad to facilitate this process.
Pad sanders operate either by oscillating the pad in small circles or moving the pad back and forth in a straight line, again for very small distances. The sanding work is accomplished when the pad sander is applied with moderate pressure to the work surface and moved back and forth with the grain of the wood. Early pad sander models employed either a rapid back-and-forth motion, called straight line sanders, or oscillated the sanding surface in small circles, called orbital sanders.
Orbital sanders oscillated the pad in a fixed pattern, though, so that small swirl marks were left on the work surface. Random orbit sanders combine the circular movement with an elliptical motion, ensuring that no part of the sanding medium traversed the same path and eliminating the swirls. A good random orbital sander approaches a belt sander in its ability to remove large amounts of stock from a workpiece, but can also do finishing work that's beyond the capabilities of most belt sanders.