Page 20 - Threading

INTRODUCTION Possible Combinations of Thread Tolerances: Diameter Diameter
Pich
Minor
undersized
Pich
Minor
8
8
Diameter Diameter
8
8
7
7
Internal
(Nut)
6
G
6
7
7
Threads

more precise H 6 6 5 5
5
4
5
4
Basic Size 4 4
3 4
4 6
3 4 5 8
more precise 3 4 4 6 h 6 - -

8
7
5
External
(Screw) 4 6 g 6 - 8 -
Threads
3 4 5 8 7 - 9 -

Pich Major
4 6 f 6 - 8 -
Diameter Diameter
-
9
5 8 7 - Pich Major
undersized e 6 - - 8 - - Diameter Diameter

7
9
8 - Pich Major
Diameter Diameter
9 -
Pich Major
Diameter Diameter
Thread accuracy can be classified by three classes: fine, medium, and coarse, depending on the length
of thread engagement (the length of interaction between the fastener and nut member (i.e. nut or
mating material for the screw) which is divided into three groups: short, normal, and long.

LE

LE

LE - length of thread engagement

18 ISCAR