Machinery's Handbook, 31st Edition
914 Reamers Helix Angle: The angle which a helical cutting edge at a given point makes with an axial plane through the same point. Hook: A concave condition of a cutting face. The rake of a hooked cutting face must be determined at a given point. Internal Center: A 60-degree countersink with clearance at the bottom, in one or both ends of a tool, which establishes the tool axis. Irregular Spacing: A deliberate variation from uniform spacing of the reamer cutting edges. Land: The section of the reamer between adjacent flutes. Land Width: The distance between the leading edge of the land and the heel, measured at a right angle to the leading edge. Lead of Flute: The axial advance of a helical or spiral cutting edge in one turn around the reamer axis. Length: The dimension of any reamer element measured parallel to the reamer axis. Limits: The maximum and minimum values designated for a specific element. Margin: The unrelieved part of the periphery of the land adjacent to the cutting edge. Margin Width: The distance between the cutting edge and the primary relief measured at a right angle to the cutting edge. Neck: The section of reduced diameter connecting shank to body, or connecting other portions of the reamer. Nominal Size: The designated basic size of a reamer overall length—the extreme length of the complete reamer from end to end, but not including external centers or expansion screws. Periphery: The outside circumference of a reamer. Pilot: A cylindrical portion preceding the entering end of the reamer body to maintain alignment. Rake: The angular relationship between the cutting face, or a tangent to the cutting face at a given point and a given reference plane or line. Axial Rake: Applies to angular (not helical or spiral) cutting faces. It is the angle between a plane containing the cutting face, or tangent to the cutting face at a given point, and the reamer axis. Helical Rake: Applies only to helical and spiral cutting faces (not angular). It is the angle between a plane, tangent to the cutting face at a given point on the cutting edge, and the reamer axis. Negative Rake: Describes a cutting face in rotation whose cutting edge lags the surface of the cutting face. Positive Rake: Describes a cutting face in rotation whose cutting edge leads the surface of the cutting face. Radial Rake Angle: The angle in a transverse plane between a straight cutting face and a radial line passing through the cutting edge. Relief: The result of the removal of tool material behind or adjacent to the cutting edge to provide clearance and prevent rubbing (heel drag). Axial Relief: The relief measured in the axial direction between a plane perpendicular to the axis and the relieved surface. It can be measured by the amount of indicator drop at a given radius in a given amount of angular rotation. Cam Relief : The relief from the cutting edge to the heel of the land produced by a cam action. Chamfer Relief Angle: The axial relief angle at the outer corner of the chamfer. It is measured by projection into a plane tangent to the periphery at the outer corner of the chamfer. Chamfer Relief: The axial relief on the chamfer of the reamer. Eccentric Relief: A convex relieved surface behind the cutting edge. Flat Relief: A relieved surface behind the cutting edge which is essentially flat.
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