Which measurement tool is best suited for critical tolerances on machined components like crankshaft journals?

The best measurement tool for critical tolerances on machined components such as crankshaft journals is the outside micrometer. This tool is specifically designed to measure the external dimensions of objects with high precision, typically within a range of 0.001 inches or 0.01 millimeters. The outside micrometer features a calibrated screw mechanism that allows for fine adjustments and precise readings, making it ideal for measuring the diameters of crankshaft journals, which require accuracy to ensure proper fit and function in an engine.

Using an outside micrometer allows technicians to check for both wear and proper size, which is crucial in maintaining the performance and longevity of engine components. Its ability to provide accurate and reliable measurements makes it indispensable in applications involving critical tolerances, where even slight deviations can impact overall functionality and safety in machinery.

In contrast, other tools such as an inside micrometer measure internal dimensions, while a feeler gauge is utilized for measuring gap widths, and plasti-gauge is used primarily to check bearing clearance and tolerance but does not provide the same level of precision in measuring external diameters as the outside micrometer. This specificity in function highlights the outside micrometer's suitability for the task at hand.