Geometrical product specifications: Basing precision of pin connection

Pinned connections in machine building are characterized with basing excessiveness and it leads to failures when assembly and operation of the tool. The paper considers connection with two pins. The general number of degrees of freedom is seven, i.e. it is more than six in one degree of freedom. So there is basing excessiveness. Here are presented the methods of solving the basing excessiveness of pinned connections: instead of cylindrical pin one uses sheared pin; one of two round holes for pins is to be done oval; to make three round holes and to put three sheared pins. The construction of a real geometric model of a pin and a tool coupling is carried out, their primary errors are defined. So geometric models are the base for making samples for new production and help to improve the quality of the technical production.