THREADING
TOOLS
S O M T A P 1 2 C A T A L O G U E
186
Tap Terminology
STANDARD LEAD (CHAMFER ANGLES)
In some countries the name “PLUG” is commonly used to indicate a Bottoming tap.
In America it is used to indicate a Second tap. To avoid confusion with American terms, the terminology adopted by
British Standard 949 1979 as shown above, should be used.
TAPER
SECOND
BOTTOMING
6 to 8 threads
3.1/2 to 5 threads
2 to 3 threads
4°
8°
23°
Short Hand and Machine, Long Shank
4°
(6-8 threads) Taper
Machine and Pipe Taps
8°
(3.1/2-5 threads) Second
23°
(2-3 threads) Bottoming
Spiral Point Taps
8°
(4-5 threads)
Spiral Flute Taps
23°
(2-3 threads)
Fluteless Taps
23°
(2-3 threads)
