Question

What should M 22 designate in pitch diameter combination?

(a) 22mm diameter with lowest fine pitch

(b) 22mm diameter with standard coarse pitch

(c) 22mm diameter with highest fine pitch

(d) 22mm diameter with all pitch

This question was addressed to me in unit test.

The query is from Diameter and Pitch Combinations in portion Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

The correct choice is (b) 22mm diameter with standard coarse pitch

Easiest explanation: When no pitch is mentioned in the designation of pitch diameter combination, it means standard coarse pitch is implied e.g., M 22 shall designate a pitch diameter combination of threads size 22 mm and coarse pitch of 2.5 mm.