The saw evolved from Neolithic tools. Archeologists have found metal-toothed Egyptian saws dating back to 2000 B.C.E., but China claims that the saw was invented by Lu Ban in the fifth century B.C.E. Early blades were of copper; the Romans then used iron and reinforced the blade at the top, holding it in a wooden frame. In the nineteenth century in Europe a rigid blade of steel with a pistol-grip handle was introduced to produce a more accurate cut.
The cutting edge of a saw blade may be either serrated or abrasive. A handsaw with a stiff serrated blade can cut on both the push and pull strokes, but flexible blades allow cutting on the pull stroke only. Each tooth is bent to a precise angle, called the "set," which is determined by the saw's intended use Some teeth are usually splayed to each side, s-6.' that the blade does not stick, or "bind," in the cut. An abrasive saw uses an abrasive disc or band for cutting.''' '
A number of different categories of hand-powered saws exist, designed either to be pushed forward or pulled backward, or both, and used by one or two people. These were followed by mechanically powered saws, using steam, water, petrol, or electricity, but they all had the same purpose of cutting large pieces of material into smaller ones. Later designs of saw include the circular saw (a rotating metal disc with saw teeth around its edge) and the chain saw (the blade is a chain carrying small cutting teeth).
Samuel Miller's invention of the circular saw in 1777 only came into use when mills became steam- powered. In 1813, Tabitha Babbitt, a Massachusetts Shaker spinner, invented a circular saw as an improvement for lumber production. An early chain saw was developed in 1830 by the German orthopedist Bernard Heine for cutting bone.
