Axis - The imaginary straight line which forms the longitudinal center line of the drill.

Back Taper - A slight decrease in diameter from front to back in the body of the drill.

Body - The portion of the drill extending from the shank or neck to the outer corners of the cutting lips.

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 to eliminate undesirable contact between the drill and the work piece.

Clearance Diameter - The diameter over the cut away portion of the drill lands.

Drill Diameter - The diameter over the margins of the drill measured at the point.

Flutes - Helical or straight grooves cut or formed in the body of the drill to provide cutting lips, to permit removal of chips, and to allow cutting fluid to reach the cutting lips.

Flute Length - The length from the outer corners of the cutting lips to the extreme back end of the flutes. It includes the sweep of the tool used to generate the flutes and, therefore, does not indicate the usable length of flutes.

Neck - The section of reduced diameter between the body and the shank of the drill.

Overall Length - The length from the extreme end of the shank to the outer corners of the cutting lips. It does not include the conical shank end often used on straight shank drills, nor does it include the conical cutting point used on both straight and taper shank drills.

Point - The cutting end of a drill, made up of the ends of the lands and the web, in form it resembles a cone, but departs from a true cone to furnish clearance behind the cutting lips.

Shank - The part of the drill by which it is held and driven.

Straight Shank Drills - Those having cylindrical shanks which may be the same or different diameter than the body of the drill. The shank may be made with or without driving flats, tang, grooves or thread.

Tang - The flattened end of a taper shank, intended to fit into a driving slot in a socket.

Tang Drive - Two opposite parallel driving flats on the extreme end of a straight shank.

Taper Shank Drills - Those having conical shanks suitable for direct fitting into tapered holes in machine spindles, driving sleeves or sockets. Tapered shanks generally have a tang.

Twist Drill - A rotary end cutting tool having one or more cutting lips, and having one or more helical or straight flutes for the passage of chips and the admission of a cutting fluid.

Machine Chucking Reamer - Used primarily in machines such as turret lathes, transfer lines, numerical control, etc. for production reaming.

Hand Reamer - Used primarily by hand utilizing wrench and driven by the square. Excellent for tool and die work, machine and repair shop. May be machine driven in some cases.

Shank - The part of the reamer which is held and driven.

Neck - The section of reduced diameter between the body and the shank.

Diameter - The diameter over the body of the reamer measured at the point.

Chamfer - The leading cutting edge of the reamer, usually 45º.

Clearance - The relief on the outside diameter of the reamer, usually running to a theoretically sharp edge or cylindrical margin as the material to be reamed dictates.

Flutes - Helical or straight grooves cut or formed in the body of the reamer to permit chip flow and form lands for proper clearance.