Which feature of a thread is checked with a thread micrometer?

The pitch diameter is the correct feature of a thread that is checked with a thread micrometer. The pitch diameter is the theoretical diameter at which the width of the threads flanks is equal, making it critical for ensuring proper fit and engagement between mating threaded parts. Measuring the pitch diameter is essential because it helps to determine how well a screw or bolt will fit into a nut or a threaded hole, affecting the mechanical performance of the assembly.

The thread micrometer is specifically designed to measure this dimension with precision, allowing for effective quality control in manufacturing processes. This measurement is more indicative of the thread's functional characteristics than the other dimensions because it directly relates to the tightness and strength of the connection.

Other dimensions such as the major diameter, minor diameter, and root depth are also important in the context of thread profiles and design but do not focus on the functional engagement of the threads in a practical application as the pitch diameter does. Understanding this differentiates why the pitch diameter is the focus when using a thread micrometer.