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Appearance quality, or bite cutting cone length is not enough to add the front cutting cone length. Cutting angle, cutting angle shall be cooperative tasks inappropriate material. Sticking to the blade using the task after local relief grinding machining of tap. Cutting edge thickness. The surface treatment of the tap. Change the cutting oil varieties and oiling method. Down cutting speed. Chip obstruction should use spiral pointed tap or spiral fluted taps. The increase of aperture. Vibration wave too sharp cut viewpoint. Cut back the amount of relief grinding is not appropriate to prevent edge thickness is too small. To prevent the grinding groove bottom. Selected durability broken tap inappropriate material to prevent obstruction (high speed steel scrap iron or using spiral pointed tap, tap, tap spiral kneading) cutting torque is too large hole diameter extended as far as possible. Shorten the tapping length. Instead of fine thread. In order to add tap sharp increase cutting angle. In order to reduce the conflict, torsion, thread clearance angle can slightly increase, the blade thickness reduction. Application of spiral groove of screw tap.