In ISO/TC 10 the standardization on the geometrical tolerancing is being discussed, and now the relationship between dimensional and geometrical tolerances is treated. In the standards concerning the accuracy specifications of screw threads and gears the geometrical tolerancing seems not to be taken into consideration. It is not always necessary to express the accuracy of screw threads and gears by using the geometrical tolerancing. But the discussion on the expression of accuracy of screw

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... ds and gears by geometrical tolerancing can clarify the meaning of their tolerances. In this report the accuracy specifications of screw threads and gears are discussed from the view point of geometrical tolerancing. One of the main conclusions is as follows: the interpretation for the pitch diameter tolerance of screw threads corresponds to the Envelope Requirement in the geometrical tolerancing, while the dimensional and geometrical tolerances in the case of gears are independent each other.