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ACTUAL SIZE: The actual measured diameter of a counterbore, often somewhat larger than the nominal diameter.
AXIAL RAKE: The angle between a plane containing the cutting face, or tangent to the cutting face at a given point, and the axis of an angularity fluted counterbore.
AXIAL RELIEF: The relief measured in the axial direction between a plane perpendicular to the axis and the relieved surface.
AXIS: The imaginary straight line, which form the longitudinal centerline of a counterbore.
BLADE: A tooth or cutting device inserted in a counterbore body.
BODY DIAMETER CLEARANCE: That portion of the land that has been cut away so it will not rub against the walls of the hole.
CLEARANCE: The space provided behind the cutting edge or margin to eliminate undesirable contact between the counterbore and the workpiece.
CLEARANCE DIAMETER: The diameter over the cutaway portion of the counterbore lands.
COUNTERBORE CUTTER: A detachable cutting portion of an interchangeable counterbore.
COUNTERBORING: A method of enlarging portions of previously formed holes.
CUTTER DIAMETER: The diameter over the margins of a counterbore measured at the cutting end.
CUTTING EDGE: The leading edge of the land in the direction of cutting.
END RELIEF: See preferred term Axial Relief.
FEED: The axial advance in inches per revolution of a counterbore with respect to the workpiece.
FLUTE LENGTH: The length of the flutes of a counterbore, not including the cutter sweep or the pilot.
FLUTED HOLDER: A fluted holding or driving member for a counterbore cutter in an interchangeable counterbore.
FLUTES: Helical or straight grooves cut or formed in the body of a counterbore to provide cutting lips, to permit the passage of chips and to allow cutting fluid to reach the cutting lips.
GAGE LINE: The axial position on a taper where the diameter is equal to the basic large end diameter of the specified taper.
HEEL: The trailing edge of the land in the direction of rotation for cutting. 300
HELICAL FLUTES: Flutes, which are formed in a helical path around the axis of a counterbore.
HELICAL RAKE: The angle between a plane tangent to the cutting face at a given point on the cutting edge, and the counterbore axis.
HELIX ANGLE: The angle, which a helical cutting edge at a given point makes with an axial plane thru the same point.
HOLDER: Applied to an interchangeable type of counterbore, the extended mounting and holding member for the cutting element, or counterbore cutter.
LAND: The section of a counterbore between adjacent flutes.
LAND CLEARANCE: See preferred term Body Diameter Clearance.
LAND WIDTH: The distance between the leading edge and the heel of the land measured at a right angle to the leading edge.
LIP RELIEF: The axial relief on the end teeth of a counterbore.
LIP RELIEF ANGLE: The axial relief angle on the end teeth of a counterbore. It is the angle between a plane perpendicular to the axis and the relieved surface.
LIPS: The end cutting edges of a counterbore, extending from the outside diameter to the pilot diameter or the pilot hole.
MARGIN: The cylindrical portion of the land, which is not cut away to provide clearance.
NECK: A section of reduced diameter connecting shank to body, or connecting other portions of a counterbore.
NEGATIVE RAKE: Describes a cutting face in rotation whose cutting edge lags the surface of the cutting face.
PRIMARY RELIEF: The relief immediately behind the cutting edge or margin. Properly called Relief.
PROJECTED LENGTH: The total distance the end face of the cutting element of a counterbore extends from the end of the machine spindle.
RADIAL RAKE ANGLE: The angle in a transverse plane between a straight cutting face and a radial line passing thru the cutting edge.
RADIAL RELIEF: Relief in a radial direction measured in the plane of rotation. It can be measured by the amount of indicator drop at a given radius in a given amount of angular rotation.
RAKE: The angular relationship between the tooth face, or a tangent to the tooth face at a given point, and a given reference plane or line.
RELIEF: The result of removal of tool material behind or adjacent to the cutting edge to provide clearance and prevent rubbing (heel drag).
RELIEF ANGLE: The angle formed between a relieved surface and a given plane tangent to a cutting edge or to a point on the cutting edge.
SHANK: The portion of a counterbore by which it is held and driven.
SOCKET: The tapered hole in a spindle, sleeve or counterbore holder, designed to receive, hold, and drive a tapered shank.
SPIRAL ANGLE: See preferred term Helix Angle.
SPIRAL FLUTES: See preferred term Helix Flutes.
SPOTFACING: The operation of producing a usually flat surface at the terminal of, and normal to the axis of a previously made hole.
STEP COUNTERBORE: A counterbore designed to produce in one operation, two or more counterbored diameters and seats at different axial locations.
STOP COLLAR: A solid or adjustable collar on the counterbore body or holder for controlling the depth of the counterboring of a hole.
STRAIGHT FLUTE: A flute, which forms a cutting edge lying in an axial plane. See Flutes.
SUBLAND COUNTERBORE: A type of step counterbore, which has independent sets of lands in the same body section for each diameter.
TANG: The flatted end of a taper shank, which fits in a slot in the socket.
TANG DRIVE: Two opposite parallel driving flats on the extreme end of a straight shank.
TAPER SHANK: A shank made to fit a specified (conical) taper socket.





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Last modified: November 06, 2001