Intro to Millwright Practice Exam

Which precision tool is used to check an inside micrometer for accuracy?

1. Caliper

2. Outside Micrometer

3. Feeler Gauge

4. Dial Indicator

The correct answer is: Outside Micrometer

The use of an outside micrometer as a precision tool to check the accuracy of an inside micrometer is based on the principle of measurement comparison. An outside micrometer measures the outside dimensions of an object with high precision, allowing it to verify the calibration and accuracy of an inside micrometer by measuring a known dimension. Inside micrometers are designed to measure the inner diameter of holes or other cylindrical features. To ensure that the inside micrometer is providing accurate readings, it can be compared with the measurements obtained from the outside micrometer, which can be used on rods or standards with known diameters. If both tools provide consistent measurements when used on the same reference piece, it confirms that the inside micrometer is functioning accurately. The other options do not serve as primary verification tools for an inside micrometer. Calipers are versatile measuring instruments but are not as precise as micrometers for checking dimensional accuracy. A feeler gauge is designed for measuring gaps or spaces, rather than for confirming the internal measurements made by an inside micrometer. A dial indicator is typically used for measuring displacements and runouts rather than directly measuring internal dimensions, which makes it less suitable for this particular application.