A method for stepping a first member relative to a second member. The method including: providing one of the first and second members with one of a plurality of pockets and movable pins offset from each other with a first spacing; providing the other of the first and second members with the other of the plurality of pockets and movable pins offset from each other with a second spacing, where the first spacing is different from the second spacing; and engaging at least one of the movable pins into a corresponding pocket to step one of the first and second members a predetermined linear and/or rotary displacement.