Calculation of the virtual pitch thread diameter using the cloud of points from CMM

This paper presents a new calculation procedure of the virtual pitch thread diameter using the cloud of points from coordinate measuring machines (CMM). The procedure involves scanning of thread profiles using a CMM, calculation of points sets belonging to the left and right thread flanks, next determination of the thread profile which belongs to the adjoining helical surface. Its parameters guarantee the required diameter calculation. Estimation of this diameter comparing it with the standard one measured by CMM “Lapik KIM-1000” and the theoretical maximum pitch thread diameter shows that this approach gives a reliable result.