Reaming Terminology
- Actual Size
- The actual measured diameter of a reamer.
- Alternate
- Reamer features which differ from each other in turn in a regular sequence such as cutting edges, chip breakers, chamfers, or flutes
- Angle of Taper
- The included angle of taper on a taper tool or taper shank
- Angular Flute
- A flute which forms a cutting face lying in a plane intersecting the reamer axis at an angle. It is unlike a helical flute in that it forms a cutting face which lies in a single plane
- Arbor Hole
- The central mounting hole in a Shell Reamer – typically tapered at 1/8" per foot
- Axial Rake
- The angle between the cutting face of a reamer and its axis, measured along the direction the tool moves. This applies only to cutting edges that are not helical or spiral.
- 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 forms the longitudinal centerline of a reamer, usually established by rotating the reamer between centers
- Back-Off
- See preferred term Relief
- Back Taper
- A slight decrease in diameter, from front to back in the flute length of reamers
- Barrel
- See preferred term Body
- Bevel
- An unrelieved angular surface of revolution (not to be confused with chamfer)
- Blade
- A tooth or cutting element inserted in a reamer body; it may be adjustable and/or replaceable
- Blending Radius
- A relieved radius joining the chamfer and the periphery
- Body
- 1) The fluted full diameter portion of a reamer, inclusive of the chamfer, starting taper, and bevel
- 2) The principal supporting member for a set of reamer blades, usually including the shank
- Burnishing Reamer
- A finishing reamer intended to take a light scraping cut and impart a fine finish
- Cam Relief
- A specially shaped relief behind the cutting edge. It helps reduce friction between the tool and the workpiece while cutting.
- Chambering Reamer
- A reamer for forming a shell chamber in a firearm.
- Chamfer
- The angular cutting portion at the entering end of a reamer (see also Secondary Chamfer)
- Chamfer Angle
- The angle between the axis and the cutting edge of the chamfer measured in an axial plane at the cutting edge
- Chamfer Length
- The length of the chamfer measured parallel to the axis at the cutting edge
- Chamfer Relief
- The axial relief on the chamfer of the reamer
- Chamfer Relief Angle
- The axial relief angle at the outer corner of the chamfer
- Chip Breakers
- Notches or grooves in the cutting edge of some taper reamers designed to break the continuity of the chips
- Chucking Reamer
- A type of precision reamer designed to be held in a chuck, typically used in lathes or drilling machines.
- Circular Land
- See preferred term Margin
- Clearance
- The space created by the relief behind the cutting edge or margin of a reamer
- Concentric/Concentricity
- See preferred terms Total Indicator Variation and Relative Eccentricity
- Core
- The central portion of a reamer below the flutes which joins the lands
- Core Diameter
- The diameter at a given point along the axis of the largest circle which does not project into the flutes
- Core Reamer
- A roughing reamer with relatively few, deep wide flutes to provide ample room for chips in reaming cored holes
- Cutter Sweep
- The section removed by the milling cutter or grinding wheel in entering or leaving a flute
- Drift
- A flat tapered bar for forcing a taper shank out of its socket
- Drift Slot
- A slot through a socket at the small end of the tapered hole to receive a drift for forcing a taper shank out of the socket
- Duplex Lead Reamer
- A reamer with one or more flutes having a different lead than the other flutes. This produces a continuous change in flute spacing (e.g. Morse Taper Duplex)
- Eccentric Relief
- A convex relieved surface behind the cutting edge
- Eccentricity
- The amount by which the reamer's cutting surface is offset from its axis. It is usually defined as half the Total Indicator Variation (TIV).
- End Cutting
- A general term describing the extent to which a reamer cuts on the end. Four types are recognized:
- 1) End Cutting on the chamfers only 180°
- 2) End Cutting to the bottom of the flutes (Core Diameter) 180°
- 3) End Cutting to the center hole or a specified diameter of circle 180°
- 4) End Cutting to the center of reamer
- End Relief
- See preferred term Axial Relief
- External Center
- The pointed end of a reamer
- Feed
- The axial advance in inches per revolution of the reamer with respect to the workpiece
- Flat Relief
- A relieved surface behind the cutting edge which is essentially flat
- Flute Length
- The length of the flutes not including the cutter sweep
- Flutes
- Longitudinal channels formed in the body of the reamer to provide cutting edges, permit passage of chips and allow cutting fluid to reach the cutting edge
- Full Indicator Reading (FIR)
- See preferred term Total Indicator Variation
- Gage Line
- The axial position on a taper where the diameter is equal to the basic large end diameter of the specified taper
- Grinding Recess
- A clearance or undercut for the edge or corner of a grinding wheel, usually necessary at a change of diameter
- Guide
- A cylindrical portion following the flutes of a reamer to maintain alignment
- Half-Round Reamer
- A reamer with a transverse cross-section of approximately half a circle and having one cutting edge – sometimes referred to as a "D" reamer
- Heel
- The trailing edge of the land in direction of rotation for cutting
- Helical Flute
- A flute which is formed in a helical path around the axis of a reamer (sometimes called a "spiral flute")
- Helical Rake
- The angle at which a helical flute cutting edge meets the body of the reamer. This angle affects how the tool enters the material and removes chips.
- Helix Angle
- The angle formed by a helical flute as it wraps around the reamer. This angle affects chip removal and cutting smoothness.
- Hook
- A curved (concave) cutting face design that influences how aggressively a reamer cuts. The shape of the hook impacts chip flow and cutting performance, especially in softer materials.
- 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
- See preferred term Starting Taper
- 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
- Line Reamer
- A reamer used to ream two or more separated holes on the same axis – frequently with a pilot and guide
- Margin
- The unrelieved part of the periphery of the land adjacent to the cutting edge
- Multiple Diameter Reamer
- A reamer with two or more cutting diameters (see also step reamer)
- Neck
- A section of reduced diameter connecting shank to body, or connecting other portions of the reamer
- Negative Rake
- Describes a cutting face in rotation whose cutting edge lags the surface of the cutting face
- Nominal Size
- The designated basic size of a reamer
- Notches
- See preferred term Chip Breakers
- Oil Grooves
- Longitudinal straight or helical grooves in shank, guide, or pilot for lubrication or to carry cutting fluid to the cutting edges
- Oil Holes
- Holes through which a cutting fluid is fed to the cutting edges 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
- Positive Rake
- Describes a cutting face in rotation whose cutting edge leads the surface of the cutting face
- Primary Relief
- The relief immediately behind the cutting edge or margin
- Pull Reamer
- Reamers which are designed to be pulled through long holes (such as gun barrels) while reamer or workpiece is rotated
- Radial Rake Angle
- See definition under Rake
- Radial Relief
- A type of relief cut behind the cutting edge, measured outward from the center of the tool. It helps reduce friction during rotation.
- Radial Runout
- The radial variation from a true circle which lies in the diametral plane and is concentric with the reamer axis. See Total Indicator Variation
- 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
- Recess
- See preferred term Grinding Recess
- Relief
- The result of the removal of tool material behind or adjacent to the cutting edge to provide clearance and prevent rubbing
- Relief Angle
- The angle, measured in a transverse plane, between the relieved surface and a plane tangent to the periphery at the cutting edge
- Relative Eccentricity
- The distance between the axis of one portion and the axis of some other portion of a reamer
- Rose Reamer
- A type of reamer with lands which are not relieved on the periphery. It has a relatively large amount of back taper
- Runout
- See Radial Runout
- Salvage Hole
- A central hole in the front end of a reamer of sufficient depth to provide for reconditioning
- Secondary Chamfer
- A slight relieved chamfer adjacent to and following the initial chamfer
- Secondary Relief
- An additional relief behind the primary relief
- Shank
- The portion of the reamer by which it is held and driven
- Size
- See terms Actual Size and Nominal Size
- Sleeve
- A tapered shell designed to fit into a specified socket and to receive a taper shank smaller than the socket
- Socket
- The tapered hole in a spindle, adaptor or sleeve, designed to receive, hold, and drive a tapered shank
- Spiral Flute
- On a taper reamer, a flute of constant lead
- Squared Shank
- A cylindrical shank having a driving square on the back end
- Staggered Flutes
- See preferred term Irregular Spacing
- Starting Radius
- A relieved radius at the entering end of a reamer in place of a chamfer
- Starting Taper
- A slight relieved taper on the front end of a reamer also reffered to as Entry Lead
- Step Reamer
- A multiple diameter reamer with all lands in each step ground to the same diameter
- Straight Flute
- Flutes that run parallel to the axis of a reamer
- Straight Shank
- A cylindrical shank
- Subland Reamer
- A type of multiple diameter reamer which has independent sets of lands in the same body section for each diameter
- Tang
- The flattened end of a taper shank which fits a slot in the socket
- Tang Drive
- Two opposite parallel driving flats on the extreme end of a straight shank
- Tangential Rake Angle
- A technical angle measured at the outer edge of the cutting face, describing how curved the hooked surface is in relation to a line pointing outward from the tool center. It affects chip removal and cutting forces.
- Taper Per Foot
- The difference in diameter between two points 12 inches apart measured along the axis
- Taper Shank
- A shank made to fit a specified (conical) taper socket
- Tongue
- See preferred term Tang
- Total Indicator Reading (TIR)
- See preferred term Total Indicator Variation
- Total Indicator Variation (TIV)
- The difference between the maximum and minimum indicator readings obtained during a checking cycle
- Undercut
- See preferred term Grinding Recess
- Web
- See preferred term Core Diameter