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

A thread micrometer is specifically designed to measure the pitch diameter of a screw thread. The pitch diameter is an important parameter because it represents the diameter at which the width of the thread ridge and the width of the thread groove are equal. This measurement ensures that the internal and external threads will properly fit together, which is critical for the mechanical function of threaded fasteners.

The key reason for using a thread micrometer to check the pitch diameter is that it allows for precise measurement that directly correlates with the functionality and fit of threaded components. The pitch diameter can be considered the effective diameter for torque transmission, making it essential for determining the load-bearing capacity and alignment of threaded parts.

Measuring the pitch diameter accurately can help identify any manufacturing discrepancies or wear that could affect the functioning of a threaded connection. While other measurements such as the major diameter, minor diameter, and root radius are also important, they do not provide the same direct insight into the mating capabilities of internal and external threads as the pitch diameter does.