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

A thread micrometer is specifically designed to measure the pitch diameter of a thread, which is a critical aspect of thread geometry. The pitch diameter is the effective diameter at which the thread flanks contact each other when two mating threads interface. This measurement is essential for ensuring that threaded parts fit together correctly and function as intended.

The pitch diameter is important in applications such as assembly and stability under load, as it directly influences how well the threads can engage without excessive play or binding. This dimension is often used in the manufacturing and quality control phases to ensure specifications are met, allowing for proper fit, strength, and performance of threaded components.

In contrast, the major diameter refers to the largest diameter of the threaded bolt or screw, and the minor diameter is the smallest diameter of the thread, which are typically measured with different tools. The flank angle, which relates to the angle formed between the flanks of the threads, is also not measured with a thread micrometer, as it requires different techniques and tools to assess accurately.