Abstract: A tool holder, which has a tool bit pivotal in a recess in one end thereof, extends coaxially through a generally bell shaped piston housing, and through the center of a piston slidably mounted on the holder for limited reciprocation in the housing axially thereof. The piston is urged by a compressing spring to a retracted position against one end of the housing, and has a reduced diameter annular wall that projects coaxially toward the end of the holder containing the tool bit. A tool actuating rod, which is pivotal in an axial bore in the holder, has on one end a lever which extends slidably into an axially extending helical slot formed in the annular piston wall, and is connected at its opposite end to the tool bit. When the piston is in its retracted position, the helical slot in its annular wall causes the actuating rod to swing the tool bit to an inoperative position within the holder recess.

Abstract: A spotfacing and counterboring tool has therethrough an axial bore communicating at one end with a recess containing a pivotal cutter blade connected to an actuator which is reciprocable on the tool between a first limited position in which it moves the cutter blade to an inoperative position within the recess, and to a second limited position in which it moves the cutter blade to an operative position in which the blade projects out of the recess. An expansion chamber in the tool communicates at one end with the axial bore in the tool, and at its opposite end is closed by the reciprocable actuator, which normally is urged resiliently into its first position, when the tool is not being used, and in which position it places the chamber in its contracted mode.

Abstract: A cylindrical tool body is chucked at one end in a drive spindle, and has in its opposite end a cutter blade pivotal into and out of a recess in the tool body between inoperative and operative positions, respectively. The pivoted end the cutter has thereon spaced teeth drivingly engaged with the teeth of a rack formed on one end of an elongate operating rod which reciprocates in an axial bore in the tool body. The opposite end of the rod is secured to one end of a radial pin, the opposite end of which projects slidably into a helical groove formed in the inner peripheral surface of an actuating ring which surrounds the tool body adjacent its chucked end. A friction ring which is rotatable on the tool body adjacent the actuating ring is frictionally engaged with the actuating ring by a friction clutch device which also surrounds the tool body adjacent the friction ring.

Abstract: Adjacent one end thereof the shank of a back spotfacing tool has therein a transverse slot, and a cutter mounting pin which extends between opposite sides of the slot parallel to the shank axis. A cutter has in one end thereof a U-shaped slot which is inserted removably over the pin to support the cutter for limited pivotal movement about the pin into and out of an operative position in which a flat, external, limit surface formed on the side of the cutter remote from the open end of its U-shaped slot engages the bottom of the slot in the shank to support the cutter for a cutting operation, and to prevent removal of the cutter from the pin. The cutter may be swung manually to an inoperative position in which the open end of its slot is positioned to permit removal of the cutter from the pin, or the replacement thereof over the pin.