Tool is any instrument that a worker uses to do work. Tools that do their tasks on a machine are called machine tools (see Machine tool). Small power-driven tools are similar to both hand tools and machine tools. The two main kinds of tools are woodworking tools and metalworking tools.
Woodworking tools.
The tools of the carpenter and cabinetmaker include such measuring tools as the rule for measuring lengths; the square and protractor for measuring angles; compasses for marking circles and arcs; and carpenter’s levels and plumb lines for ensuring that carpentry work will be straight and true. Vises and clamps hold material in place while it is being shaped. Shaping tools include saws, chisels, planes, files, and boring bits. Woodworkers also use hammers, hatchets, screwdrivers, and pliers. See Woodworking.
Metalworking tools.
The work of the machinist and toolmaker ordinarily requires much greater precision than that of the woodworker. Thus, measuring tools for metalworking must be very accurate. Many micrometers and calipers can measure distances as small as 1/10,000 inch (0.0025 millimeter). The hacksaw used for cutting metal is thinner and harder than the woodworking saw. Machinists use taps and dies to cut threads in machine parts. They also use wrenches for repair work and in assembling machinery. Most machining operations on metal parts are done by machine tools, such as lathes, milling machines, shapers, and grinders.
History of tools.
Prehistoric people learned that rocks and sticks of certain shapes could help them do things they could not do with their bare hands. They later improved the natural stones they used. They shaped them into knives, hatchets, and hammers, and attached wooden handles to them. Stone Age people developed a drill for drilling soft stone and wood. Bronze Age people developed new tools, such as tongs for holding hot objects. Agricultural civilizations later developed new tools, such as the hoe and the simple plow.
After people learned to work iron and steel, they developed stronger, sharper, and more durable tools. The development of steam engines, gasoline engines, and electric motors made it possible to replace hand tools with machine tools. Today, much work once done by hand is done by small power tools.
