Geometric error modeling of the contact probe in a three-dimensional screw thread measuring machine

In this study, the influence of the geometric error of a contact probe on the accuracy of thread measurement was investigated to improve the measurement accuracy of three-dimensional (3D) screw thread measuring machines. The structure and measurement principle of the 3D thread measuring machine were studied, and the geometric error sources of the contact probe were analyzed. The principles of space coordinate transformation and the geometric theorem were used to establish a geometric model of the error sources. The experimental platform and the standard ball measurement of the three-coordinate machine were configured to verify the geometric error model. The results revealed that the measurement error was significantly reduced after compensation by the model. The proposed geometric error modeling method provides a clear theoretical basis for the accurate compensation of contact probe deviations and further improves the measurement accuracy of 3D thread measuring machines.