Which tool is used to determine piston pin out-of-round wear?

The micrometer caliper is particularly well-suited for measuring the dimensions of small components, such as piston pins, with high accuracy. In the context of assessing piston pin out-of-round wear, its ability to measure the diameter precisely at different points along the pin is crucial. When a piston pin exhibits out-of-roundness, it will show different measurements depending on the orientation in which it is measured.

Using a micrometer caliper allows the technician to take precise readings at various angles around the pin, which can help identify any irregularities in shape. This information is vital for determining the extent of wear and whether the piston pin can still function effectively or if it needs to be replaced. The other tools listed may serve specific purposes in measurement but lack the precision or suitability required for this particular type of assessment.