Abstract: A portable motor-driven cutter for cutting off a sheet material includes an eccentric shaft rotatably supported by a gear case and a gear cover, an L-shaped driver arm having an upper end rotatably fitted over an eccentric portion of the eccentric shaft, a cutting blade detachably mounted on the lower end of the driver arm, and a scribing blade detachably mounted on a base on which the gear case is mounted. When the eccentric shaft is rotated by a motor, the cutting blade is moved in an eccentric pattern to cut off a sheet material along a straight line scribed by the scribing blade. The cutting blade and the scribing blade are produced from a single break-off disposable cutter blade.

Abstract: A circuit arrangement including a computer is built in an electrical jig saw where various data or information, such as the sort of the material of the workpiece, the thickness of the workpiece, desired degree of finish and way of cutting, are manually inputted via a keyboard so that the computer selects and determines optimum working condition, such as the sort of blade to be used, the locus of the blade, blade strokes per minute which is in proportion to the motor speed, and the necessity of application of coolant oil. The circuit arrangement also comprises circuitry for automatically controlling the rotational speed of the motor of the jig saw so that an actual speed of the blade equals a desired speed represented by strokes per minute. A display unit is coupled with the computer for indicating input and output data of the computer for supplying visual information to the user of the jig saw.

Abstract: A power driven percussion tool is provided with a rotatable magazine block formed with a plurality of bores about the axis of rotation of the magazine block and is loaded with fasteners such as rivets or nails respectively retained in the bores. When the magazine block is stepwise rotated about its axis the bores are successively brought into alignment with the direction in which the fastener can be driven by a reciprocating hammer. The percussion tool is further provided with safety means for disabling the tool when the tool is not in use or being re-loaded with fasteners.