Question

Which of the following tolerance grades can be used for minor diameter and pitch diameter of internal threads?

(a) 4, 6, 8

(b) 3, 4, 5, 6, 7

(c) 3, 4, 5

(d) 4, 5, 6, 7, 8

The question was posed to me during an internship interview.

This is a very interesting question from Diameter and Pitch Combinations in chapter Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

Correct choice is (d) 4, 5, 6, 7, 8

Best explanation: The tolerance grades recommended for minor diameter and pitch of internal threads are 4, 5, 6, 7, and 8 and for major diameter of external threads and for pitch diameter of external threads are 4, 6, 8 and  3, 4, 5, 6, 7, 8, 9 respectively.