Why Is Pitch Diameter Important?

Pitch diameters are an essential component in determining the compatibility between internally and externally threaded parts – nuts and bolts, for example – and are also used as an important frame of reference for other thread measurements.

What is the effective diameter of a thread?

The pitch diameter (often called the effective diameter) of a parallel thread is the diameter of the imaginary co-axial cylinder which intersects the surface of the thread in such a manner that the intercept on a generator of the cylinder, between the points where it meets the opposite flanks of a thread groove, is ...

What's a pitch diameter?

PITCH DIAMETER-The basic thread pitch diameter is the diameter where the thread thickness is equal to the space between the threads. If the flats at the top and bottom of the thread are the same, the pitch diameter will coincide with the middle of the sloping side of the thread.