Millwright Certification Precision Measuring and Layout 2

Question 1

What is the resolution of a standard metric outside micrometer with a thimble graduated in 0.01 mm divisions?

Accepted Answer

0.01 mm

Answer

A standard metric micrometer reads to 0.01 mm resolution using the combination of the sleeve scale (0.5 mm divisions) and the thimble scale (0.01 mm divisions around the circumference).

Question 2

When using a dial indicator to check shaft runout, what does a Total Indicator Reading (TIR) of 0.05 mm mean?

Accepted Answer

The maximum indicator deflection from lowest to highest reading during one full rotation is 0.05 mm

Answer

TIR (Total Indicator Reading) is the difference between the maximum and minimum dial indicator readings during one complete shaft rotation, representing the total runout of the surface being measured.

Question 3

What is the proper technique for measuring with a telescoping gauge?

Accepted Answer

Compress, insert into the bore, lock at the correct contact feel, then measure the gauge with a micrometer

Answer

Telescoping gauges are transfer instruments: the plungers are compressed, inserted into the bore, then gently rocked to find the maximum diameter contact point, locked, withdrawn, and measured with a micrometer.

Question 4

Why must precision measuring instruments be allowed to equalize to the same temperature as the workpiece before measuring?

Accepted Answer

Thermal expansion causes dimensional changes that create measurement errors

Answer

Metals expand and contract with temperature changes. If the instrument and workpiece are at different temperatures, their dimensions will differ from their nominal values, causing measurement errors that can exceed tolerances.

Question 5

What is a surface plate used for in precision layout and measurement?

Accepted Answer

As a flat reference plane for layout work, height measurements, and checking flatness of components

Answer

A surface plate provides an extremely flat reference plane (typically granite, lapped to within micrometers) used as a datum surface for layout work, height gauge measurements, and checking component flatness.

Blog Practice Test

Blog Practice Test

Millwright Certification Precision Measuring and Layout 2