General Details: A circular saw is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbour. A hole saw and ring saw also use a rotary motion but are different from a circular saw. The Circular saws may also be loosely used for the blade itself. A Circular saws were invented in the late 18th century and were in common use in sawmills in the United States by the middle of the 19th century. Circular saw blades are specially designed for each particular material they are intended to cut and in cutting wood are specifically designed for making rip-cuts, cross-cuts, or a combination of both. Circular saws are commonly powered by electricity but may be powered by a gasoline engine or a hydraulic motor which allows it to be fastened to heavy equipment, eliminating the need for a separate energy source.