Saw is a cutting tool that has a metal blade with sharply pointed teeth along one edge. Saws cut wood and almost any other material, including plastics and steel.
A saw’s teeth slant alternately to the left and right. This system of slanting, called saw set, helps the saw move through the material being cut. As a saw cuts, the teeth remove some of the material as sawdust and form a channel wider than the blade. The blade slides through this channel, called a kerf, without sticking.
The size of a saw’s teeth determines the smoothness of the cut. The more tooth points per inch of blade, the smaller the teeth–and the smoother the cut surface. Most saws used for cutting lumber into smaller pieces have 51/2 to 10 points per inch. For fine work, saws with as many as 20 points per inch may be used.
There are two main kinds of saws: (1) handsaws and (2) power saws.
Handsaws
are alternately pulled and pushed with a back-and-forth motion. Some make only straight cuts, and others make both straight and curved cuts.
Several types of handsaws may be used for straight cuts in wood. A crosscut saw cuts across the grain of a board. A ripsaw cuts lengthwise with the grain. A backsaw moves both across and with the grain. Craftworkers often use a backsaw along with a tool called a miter box, which guides the blade for accurate cuts.
To cut curves in thin boards, craftworkers may use a coping saw. This saw has a thin, flexible blade fastened at each end across a U-shaped frame. Keyhole saws and compass saws cut curves in thick boards. They have a narrow, rigid blade with a handle on one end.
Straight or curved cuts in metal are made with a hacksaw. Various replaceable blades of hardened steel cut different kinds and sizes of metal objects.
Power saws
are driven by an electric motor or a gasoline engine. Some are mounted on a special table, and others are held by hand. Most power saws can be fitted with various types of blades to cut different materials. The blades of power saws move at great speed.
The most widely used type of power saw is the circular saw. Its disklike blade makes straight, accurate cuts. Circular saws may be table-mounted or handheld.
To make straight or curved cuts, craftworkers use a table-mounted or handheld jigsaw. This saw has a thin blade that moves up and down at high speed. A hand-held saber saw also uses this type of motion. The band saw is a table-mounted power saw used for straight or curved cuts. This saw’s blade is an endless flexible steel band that rotates between two large pulleys.
A handheld power saw called a chain saw is used to cut trees and heavy timber. The saw’s teeth are attached to an endless moving chain.
