Mechanical device comprising a plurality of parts assembled together with accurate relative positioning

A mechanical device comprising an assembly of a plurality of parts that are fastened to one another and that need to be accurately positioned relative to one another, wherein at least one of the parts includes two ribs in a chevron configuration, and wherein at least one other part includes two grooves in a chevron configuration, the ribs and the grooves being of complementary shapes and of corresponding dimensions, said parts becoming positioned one relative to another on assembly by mutual engagement of said ribs and grooves of chevron configuration engaging mutually.