Pitch and pitch diameter are two crucial details to know when ordering threaded products. Learn more about both in our latest blog.
Pitch is the distance from a point on the screw thread to a corresponding point on the next thread, measured parallel to the axis, typically measuring the distance between thread crests.
For Unified—imperial (inches/ feet) items, the thread pitch is defined by the number of threads per inch. For metric (millimeters/ meters) items the thread pitch is defined by the distance in millimeters between two threads.
Pitch Diameter is the simple effective diameter of screw thread, approximately halfway between the major and minor diameters. It can also be explained as the diameter of an imaginary cylinder that passes through the threads and intersects the thread flanks at equidistant points. Pitch diameter is measured by either dedicated micrometer screw gauges, the three-wire method, or optical comparators.