Relief-Space – Provided by removing material immediately behind the cutting edge. Done to eliminate the possibility of heeling or rubbing.

Gash (Notch) – The secondary cuts on a tool to provide chip space at corners and ends. The space forming the end cutting edge, which is used when feeding axially.

Tangential rake angle – The angle made by a line tangent to a hooked tooth at the cutting edge & a radius passing through the same point in a plane normal to the axis.

Radiused cornerangle

Gash width – The width of the gash feature. The space between cutting edges, which provides chip space and resharpening capabilities. Sometimes called the flute.

Radius Base OutsideCornerMoulding

The distinction between the corner radius and the effective turning radius is crucial and often overlooked. The corner radius may be a simple or a complex curve and depends primarily on the presence of on-street parking, bike lanes, the number of travel lanes, medians, and traffic control devices.

Joseph E. Hummer, Charles V. Zegeer, and Fred R. Hanscom, Effects of turns by larger trucks at urban intersections, (Charlotte, N.C.: Transportation Academy, Dept. of Geography and Earth Sciences, University of North Carolina at Charlotte, 1988).

Flute – Space between cutting teeth providing chip space and regrinding capabilities.  The number of cutting edges.  Sometimes referred to as “teeth” or “gullet”.  The number on an end mill will determine the feed rate.

Angular Edge – The cutting edge that is a straight line and forms an angle with the cutter axis. The cut that an Angular edge tool produces will not be as flat as a helical cutting edge.

Helix Angle – The angle formed by a line tangent to the helix and a plane through the axis of the cutter or the cutting edge angle which a helical cutting edge makes with a plane containing the axis of a cylindrical cutter.

Radius corners for Cabinets

Differential pitch cutters – A specifically designed variation in the radial spacing of the cutter teeth. This provides a variation in tooth spacing and can be beneficial in reducing chatter. This concept is based on reducing the harmonic effect of the tool contacting the part in an exact moment of vibration.

Back taper – A slight taper resulting in the shank end of the cutting diameter being smaller than the cutting end. This condition aids not only the plunging or drilling condition but also tends to compensate for deflection.

MDF RadiusCornerMoulding

Entrance Angle – The angle formed by a line through the center of the cutter at 90 to the direction of feed and a radial line through the initial point of contact. As this angle approaches 90 degrees the shock loading is increased.

Chip Splitters – Notches in the circumference of a corn-cob style Endmill cutter resulting in narrow chips. Suitable for rough machining.

Radiused cornermeaning

Hook – A term used to refer to a concave condition of a tooth face. This term implies a curved surface rather than a straight surface.  Hook must be measured at the cutting edge, making measurement difficult.

Cutting Edge – The leading edge of the cutter tooth.  The intersection of two finely finished surfaces, generally of an included angle of less than 90 degrees.

In urban settings, smaller corner radii are preferred and actual corner radii exceeding 15 feet should be the exception.

3 radiuscornercountertop

Kendra K. Levine, Curb Radius and Injury Severity at Intersections (Berkeley: Institute of Transportation Studies Library, 2012), 2.

Core Diameter – The diameter of a cylinder (or cone shape with tapered Endmills) tangent to the flutes at the deepest point.

Plywood Radius Corners

Concave – Small hollow required on the end face of an Endmill. This feature is produced by a dish angle produced on the cutter.

Chamfer – A short relieved flat installed where the periphery and face of a cutter meet. It is used to strengthen the otherwise weak corner.

Helical – A cutting edge or flute which progresses uniformly around a cylindrical surface in an axial direction. The normal helical direction is a right direction spiral.

Designers often determine corner radii based on the intersection geometry only and overlook the effective radius. As a result, drivers making a turn on a green signal have little incentive to turn into the nearest receiving lane and routinely turn as wide as possible to maintain travel speeds.

Rake – The angular relationship between the tooth face or a tangent to the tooth face at a given point and a reference plane or line.  An angular feature ground onto the surface of an end mill.

RadiusCornerMoulding

Corner radii directly impact vehicle turning speeds and pedestrian crossing distances. Minimizing the size of a corner radius is critical to creating compact intersections with safe turning speeds. While standard curb radii are 10–15 feet, many cities use corner radii as small as 2 feet.

Axial Runout – The difference between the highest and lowest indicator reading that is taken at the face of a cutter near the outer diameter.

Dish Angle – The angle formed by the end cutting edge and a plane perpendicular to the cutter axis. Dish ensures that a flat surface is produced by the cutter.