S O M T A P 1 2 C A T A L O G U E
183
THREADING
TOOLS
Tap Terminology
Under favourable working conditions, the following thread tolerances should be produced by the new class taps.
All Somta HSS taps are supplied to Class 2, 6H unless otherwise specified.
TAP THREAD TOLERANCE
BASIC THREAD FORMS
COMPONENT ELEMENTS
NUT
MAJOR DIA.
PITCH DIA.
MINOR DIA.
THREAD
ANGLE
HELIX ANGLE
AT PITCH DIA.
PITCH
SCREW
Metric
Unified
Whitworth Form
BA
Class 1
4H, 5H
3B
Close Class
Close Class
Class 2
6H, 4G, 5G
2B
MediumClass
MediumClass
Class 3
7H, 8H, 6G
1B
Free Class
Free Class
