SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING When very high accuracy is of importance the inaccuracies in the shaping cutter matter since they may transfer to the cut gear. It is obvious that profile errors will transfer but it is less 偏 obvious than an eccentrically mounted or ground cutter will C give a characteristic dropped tooth?. There are several causes 的 for " dropped tooth" but it occurs most commonly when the diameter of the workpiece is about half, one and a half, two and a half etc times the cutter diameter If the cutter starts on a high point and finishes on a low point during the final finishing revolution of the gear the peak to peak eccentricity error in the cutter occurs between the last and first tooth of the final revolution of the cut gear; as the cumulative pitch error of the cutter may well be over 25 microns there is a sudden pitch error of this amount on the cut gear. The next gear cut on the machine may however be very good on adjacent pitch if the final cut happened to start in a favorable position on the cutterSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING When very high accuracy is of importance the inaccuracies in the shaping cutter matter since they may transfer to the cut gear. It is obvious that profile errors will transfer but it is less obvious than an eccentrically mounted or ground cutter will give a characteristic “dropped tooth”. There are several causes for "dropped tooth" but it occurs most commonly when the diameter of the workpiece is about half, one and a half, two and a half, etc. times the cutter diameter. If the cutter starts on a high point and finishes on a low point during the final finishing revolution of the gear the peak to peak eccentricity error in the cutter occurs between the last and first tooth of the final revolution of the cut gear; as the cumulative pitch error of the cutter may well be over 25 microns there is a sudden pitch error of this amount on the cut gear. The next gear cut on the machine may however be very good on adjacent pitch if the final cut happened to start in a favorable position on the cutter. 偏 心 的