A disk sander is a power tool used for sanding wood, metal or plastic. It consists of an electric motor driving a round abrasive disk, backed by a rubber pad, in a circular motion. The motion of the sanding disk creates cross grain scratches, which is why disk sanding should only be used for reducing surface thickness or removing old finishes. A simple form of this tool can be made by using a special chuck on a power drill which attaches the sanding disk and pad in place of a drill bit.
The rubber disk pad flexes in order to keep the abrasive surface flat to the work surface when the sander is held at an angle. Alternatively, solid metal disks are available that have a ball joint fitted to the shaft which accomplish the same thing.
The disks themselves consist of abrasive material such as silica bonded to a paper backing; another type consists of grains of tungsten carbide bonded to the surface of a pressed metal disk.
The abrasive disk is attached against a backing disk with a threaded screw and washer in the center. The washer and screw head are countersunk to be below the abrasive surface of the disk.
Types of Sanders
Large offset sanders are available with disks mounted at a 90 degree angle to the shaft and motor. These are useful for sanding floor or wall surfaces as they can cover large areas due to the 7 and 9 inch diameter disks they are fitted with. These tools are expensive industrial machines, but renting one may be a good option if you have heavy duty work to do on a project.
For shaping work, a bench mounted sander can be set up using a horizontal drill stand, a power drill, and a worktable. Make sure the worktable is normal to the face of the abrasive disk, using a carpenter’s try square before use. Miter grooves in the table can be set up to sand work ends square or angled.