Asking about the main positioning mode of welding in white body

Because you have a round pin on the right front, if there are no other restrictions on the XY plane of the car body (the positioning in the Z direction depends on the bracket, and the indenter is not analyzed here), then the car body can only rotate around this round pin. If the car body does not rotate in the XY plane, it only needs to control the degree of freedom in the X direction or the Y direction. At this time, if a round hole or a square hole is opened, the fixture will be over-positioned with a round pin. If the two positioning holes are both circular, the auxiliary positioning pin should be made into a diamond pin when making the fixture, and it is a better choice to make a waist hole, because this can not only prevent over-positioning, but also make it easy to see which of the two holes is the main positioning hole and which is the auxiliary positioning hole when doing positioning analysis. Moreover, the positioning pin can be made into a round pin, which makes the fixture assembly interchangeability better.