Saw

Saw, tool with a metal blade designed to cut wood, plastic, metal, and other materials. The blade of a saw has small, sharp metal teeth along the cutting edge. The teeth are slightly bent alternately to either side of the blade; this makes the kerf (groove) cut by the saw slightly wider than the blade itself, preventing the saw blade from binding against the material being cut. There are basically two kinds of saws: handsaws and power saws.

These include the cross-cut saw, the ripsaw, the backsaw, the hacksaw, and the coping saw.

Cross-cut saws and ripsaws both have wooden or plastic handles attached to metal blades that are usually between 50 and 60 cm (20 and 24 in) long. The blade is about 12 cm (5 in) wide at the handle, and tapers down to about 5 cm (2 in) at the tip. The metal teeth of a cross-cut saw are designed to cut wood across the grain; the teeth of a ripsaw are designed to cut wood with the grain.

Backsaws have a rectangular blade between 30 and 40 cm (12 and 16 in) long and are used to cut either with or against the grain. The edge of the blade opposite the cutting edge is reinforced with a strip of metal to keep the blade straight while cutting. A backsaw is often used with a mitre box, a device that guides the backsaw to make cuts straight and precise.

Coping saws have a thin, flexible blade about 20 cm (8 in) long attached to a U-shaped frame and are used to make curved cuts in wood. Hacksaws, which are usually used to cut metal and other hard materials, are slightly longer than coping saws, and also have a blade attached to a U-shaped frame. However, the blades of hacksaws are wider, stronger, and less flexible.

These include the portable circular saw, jigsaw, and chain saw. Probably the most widely used power saw is the portable circular saw, a hand-held saw with an electric motor that rotates a circular blade at high speed. By using a circular blade with the appropriate hardness and tooth design, portable circular saws can cut almost any material. A jigsaw, which is shaped like a “U” on its side, uses a thin blade which, like the blade of a coping saw, enables the user to make curved cuts in wood. The wood to be cut rests on a flat platform that is fastened between the arms of the U-shaped frame; the blade passing through a hole in the centre of the platform is attached to the ends of the U-shaped frame. An electric motor moves the blade up and down quickly, and the user pushes the wood on the platform into the blade to make a cut. Chain saws, which are used to cut heavy timber and trees, are hand-held saws with an electric motor attached to a metal blade; the motor continuously moves a cutting chain around the edge of the blade. See Machine Tools; Woodworking.