Final answer:
The pitch diameter of a hand tap determines the diameter of the threaded hole, being essential for the proper fit and engagement of threaded parts.
Step-by-step explanation:
The pitch diameter of a hand tap determines the diameter of the threaded hole. This measurement is crucial as it corresponds to the theoretical diameter at which the widths across the threads and the widths across the gaps between the threads are equal. The pitch diameter is considered the most important feature in the tap design because its accuracy determines the fit of the threaded parts.
Importance of Accurate Pitch Diameter
An accurate pitch diameter ensures that the bolt or screw will fit properly into the tapped hole. It is neither the outermost diameter of the threads (major diameter) nor the innermost (minor diameter), but rather an intermediate measurement that guides the creation of the threads to ensure proper engagement between mating parts.