A saw is a cutting tool for cutting material into smaller pieces, usually by means of some abrasive mechanism, either angled teeth or an abrasive harder than the material to cut. As opposed to a drill, it generally cuts on a plane rather than making a hole, although there are some hybrid devices called hole saws.
Basic hand saws
While the earliest saws were no more than edged stones, wood-cutting, muscle-powered saws were among the earliest tools. They are of two basic blade and tooth designs, crosscut optimized to cut across the woodgrain, and rip to cut in parallel with the grain.
Depending on the fineness of the work to be done, the teeth can be large and coarse, or small and fine. Saws intended for hard materials such as metal often have very small teeth, to minimize the energy needed to drive each tooth through the work, and also to reduce frictional heating.
There are several basic types of power saw, especially for woodworking. The three basic cutting mechanisms are a rotating circular blade, an oscillating straight blade, or a blade made of a continuous band or chain.
Circular saws may be handheld, or be either mounted on a bench or free-standing. Handheld circular saws almost always are used from above the work; a guard precedes the blade and raises just enough for it to cut. Since the point of entry is more likely to splinter, if one side of the work is finished, the cutting is apt to be done on the rough side. Further, in the usual means of operation, the work is pushed through the table saw, but the work stays stationary while the radial saw, on a moving carriage, is pulled through it.
Of the main types of stationary circular saws, the table or bench saw cuts from below the work, while the radial saw cuts from above it. While the blades are interchangeable, once mounted, a table saw blade usually stays in one position while the work moves into it, while a radial saw blade is in a moving carriage that moves across the work.
Of the oscillating types, the most basic distinction is whether the mount for the blade holds it at one end or at both ends. Single-ended mounts, such as on a saber saw or reciprocating saw, do not necessarily need a pilot hole to make an interior cut. Their blades are usually stronger, and not necessarily as precise, as those held at both ends.
Bandsaws have some of the attributes of a jigsaw, in that the blade is supported at both ends, but the blade is usually much stronger than the blade of a jigsaw. High-powered bandsaws can cut tough metal; they are an equivalent of a power hacksaw.