Anyone in the fastener or screw machine business producing screw threads is familiar with ‘pitch’ micrometers. These relatively simple devices are often used to set up production equipment and monitor their output, but there are many misconceptions about them which can call their usefulness into question. Problems arise when they are misapplied to various situations caused by the names they are known by and how they do what they do.
Problems that bring their value into question occur when there is an unacceptable spread in measurements between users or they indicate a screw thread is acceptable but other devices such as fixed limit gages reject them. A similar situation can arise when one type of this instrument says one thing while one of another type indicates something different and both of these are brought into question when a normal type of micrometer with thread wires is used to ‘measure’ a screw thread.