The measurement method of the large inner diameter and small opening size is generally as shown in Fig. 1, and the measuring tool is mainly composed of the same contact, the rotating lever and the dial indicator. When measuring, the contact measurement is displayed by the lever mechanism and then by the dial indicator. When measuring the size of the small inner diameter and small opening, the contact is longer (the contact) and the stop (?) are worse, and the lever mechanism makes the measurement error increase, and the precision is difficult to ensure.
Large inner diameter small stop size measurement