Which tool is primarily used for precise measuring in metalworking?

The caliper is the primary tool used for precise measuring in metalworking due to its ability to measure internal and external dimensions as well as depths with high accuracy. Unlike a ruler, which typically offers a limited level of precision, calipers can provide measurements down to fractions of a millimeter or inch, making them vital for applications where exact dimensions are crucial.

Calipers come in various forms, including digital and dial types, allowing for easy reading and enhanced accuracy. This level of precision is especially important in metalworking where tight tolerances are required for proper fit and function of components. While other tools like squares, rulers, and protractors serve important roles in measuring or checking angles and straightness, they do not match the versatility and precision of calipers for dimensional measurements in metalworking. The square is mainly for verifying right angles, the ruler is primarily for straight-line measurements, and the protractor specifically assists in measuring angles, none of which provide the comprehensive measuring capabilities that calipers do.