Question

What is the virtual change in effective diameter caused by pitch error in whitworth thread?

(a) 1.821 X pitch error

(b) 1.921 X pitch error

(c) 1.111 X pitch error

(d) 1.211 X pitch error

This question was addressed to me in quiz.

My enquiry is from Effect of Pitch Errors in chapter Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

Correct answer is (b) 1.921 X pitch error

To elaborate: If p is the error in a pitch for a whitworth thread, then the virtual increase or decrease in the thread effective diameter in case of bolt or nut is given by the formula: Virtual change in effective diameter = 1.921 x p.