one of the authors made a mathematic model in his paper A study of the qualified tooth-shape section of gear hobs“ published by the Journal of HIT No.1, 1984, which imitated the technological process of gear hobs and was verified through calculations and practical production in factories. This paper is a further discussion on the subject described above for the purpose of raising much greater the precision of gear hobs. Therefore it is not difficult for one of the authors made a mathematic model in his paper A study of the qualified tooth-shape section of gear hobs ”published by the Journal of HIT No. 1, 1984, which imitated the technological process of gear hobs and was verified through calculations This practical application was made in factories. This paper is a discussion on the subject described above for the purpose of raising much greater the precision of gear hobs. Therefore it is not difficult for