COUNTERBORE
& COUNTERSINK TERMS:
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.
CLICK HERE FOR GLOSSARY OF
METALWORKING TERMS
BACK TO HELPFUL HINTS
