Question

What is the reference gauge tolerance for 6” diameter gauge?

(a) 0.001”

(b) 0.002”

(c) 0.003”

(d) 0.004”

This question was addressed to me during an interview.

This is a very interesting question from Screw Thread Gauge Tolerance in portion Metrology of Screw Thread, Gauges for ISO Metric Screw Threads of Engineering Metrology

Answer 1

The correct option is (a) 0.001”

The best I can explain: Tolerances were graded in terms of diameter. The workshop and inspection tolerance on gauges for 6” inches is 0.002” on effective diameter. Reference gauge tolerance was half of these tolerances i.e. 0.001” for 6”.  This tolerance included the virtual effect of pitch and angle errors.