Electric Power Tool

a portable power tool that is driven by an electric motor and that is used for the machining of materials. An electric power tool usually consists of a housing and an electric motor, the rotor of which is connected to a spindle or mandrel by means of a sleeve or a reduction gear.

A long rotor shaft may sometimes also serve as a spindle. In some cases—for example, in an electric plane—the rotor of an inverted motor, in which the stator is inside the rotor, is used as a cutter shaft. Rotary motion is sometimes transmitted from an electric motor to a working member by means of a flexible shaft.

An electric power tool has handles for carrying it and for guiding it during its operation. To reduce the weight of such a tool, the housing and certain other parts are made of a light alloy. The power rating of the electric motor is usually not higher than 0.4–1.0 kilowatt.

Electric power tools are intended mainly for carrying out small jobs and are used to mechanize manual operations in the performance of fitting, installation, assembly, or finishing work. They are also employed to machine places on articles that cannot be reached by tools on stationary machines.

In metalworking, electric power tools are widely used. To mechanize metal chipping, electric chipping hammers are employed. In such a chipping hammer, the rotation of an electric motor’s shaft is converted into the reciprocating motion of a chisel or cape chisel attached to the hammer. In metal cutting, various power hacksaws and circular saws are used. In the cutting of sheet steel up to 3 mm thick, vibration-type power shears are employed. Such shears, which can cut up to 3–6 m/min, are especially convenient in cutting from a pattern. In filing, both electric filing machines and power-driven files are used.

Various types of power-driven hand drills, or electric drills, are employed to drill or ream holes. They include light-, medium-, and heavy-duty drills, which are used to make holes with diameters of up to 9, 15, and 30 mm, respectively, as well as corner drills, which are employed to produce holes in places that are hard to reach. To mechanize thread cutting, electric thread cutters or electric drills with special attachments are used. In scraping, electromechanical power scrapers and power-driven scraping heads are used.

In woodworking, the most widely used electric power tools are power saws, electric planes, electric milling cutters, electric drills, electric mortising machines, power grinders, knot trimmers, and portable parquet finishers.

Electric power tools also include electric nut wrenches, power fretsaws, power screwdrivers, electric hammers, and power compactors, as well as auxiliary equipment, such as tool-grinding machines and sharpeners. Certain types of electric power tools come equipped with various interchangeable cutting tools. (See alsoPOWER TOOL.)