Question

What is the equivalent of pitch and angle tolerance on effective diameter for gauges upto 1.5” diameter as per B.S.S. No. 919?

(a) 0.0004”

(b) 0.0005”

(c) 0.0006”

(d) 0.0007”

I had been asked this question during an interview.

Question is from Screw Thread Gauge Tolerance topic in portion Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

Correct choice is (b) 0.0005”

For explanation I would say: For gauges upto 1.5″ diameter, Equivalent of pitch and angle tolerance on effective diameter = 0.0005″. The simple effective diameter tolerance on NO GO gauge was same but virtual tolerance was halved. It is due to the fact that short length of thread is not liable to much pitch error.