The tubing joint shown in Figure 1 is a spare part in the clutch sub-pump of the automotive component processed by our factory. Since the conical size (?) 5.5mm is deep in the internal position of the part and the shape is small, the detection is difficult. In order to accurately measure and accurately process, we are based on the following principle: the consistency of the radial indication value of the small end of the cone can be converted into the consistency of the length of the axial indication, and the gauge of Figure 2 is designed.