Fixing method of trampoline rotation center

In an ordinary horizontal trampoline, in order to ensure the coaxiality of the U-turn hole, the center of rotation must be accurately aligned. Since the machine coordinate ruler is a general ruler, the center of rotation cannot be positioned at an accurate value. Therefore, when machining various parts without a lateral positioning reference, it is necessary to find the center of rotation every time, which is time consuming and difficult to find. . In practice, I have explored a method of fixing the center size to ensure the coaxiality of the parts that are turned over. Now introduced as follows: