TYPES AND USES
Taps and dies are used to cut threads in metal, plastics
or hard rubber. The taps are used for cutting internal
threads, and the dies are used to cut external threads.
Taps are made of hardened steel and have the following
parts: a square end (1), a round shank (2), a body
(threaded) section (3), and a chamfer (4). The square
end is used to turn the tap with either a straight or T-
handled tap wrench. The shank is a smooth, rounded
section which is immediately behind the threaded
section. The body (threaded) section contains four
flutes which have threads cut into their upper edges.
They have a hollow section near the center to permit
metal shavings to fall away from the cutting edges. The
chamfer is the non-threaded end of the tap. It allows the
tap to be positioned squarely in the metal to be threaded
without engaging the threads of the tap.
TAPER (STARTING) HAND TAP
(nonthreaded) length equal to eight to ten threads. The
taper hand tap is used to start tapping operations.
BOTTOMING HAND TAP
The bottoming hand tap has a chamfer length equal to
one to one and one-half threads. This tap is used for
threading the bottom of a blind hole only after the taper
and plug taps have been used.
This tap is also used when tapping hard materials.
PLUG/PIPE HAND TAP
The pipe tap has a tapered diameter which increases at
a rate of 3/4 inch per foot. All the threads on the pipe
tap are designed to cut pipe. The pipe tap is used for
cutting pipe fittings and in other places where extremely
tight fits are required.
BOILER HAND TAPS
There are two types of boiler taps, straight and tapered.
Straight boiler taps range in size from 1/2 inch to 1-1/2
inches in diameter and have a chamfer for starting the
Tapered boiler taps have tapered diameters which
increase at a rate of 3/4 inch per foot.