Interior Doors ,Interior Bifold Doors,Cheap Bedroom Doors,Hollow Core Interior Doors Foshan QI'AN Fireproof Shutter Doors Co., Ltd , https://www.fsqianfiredoor.com The size of the M18×1.5 set screw grinding process is shown in Fig. 1. The outer diameter of φ18mm is used for positioning, and the outer diameter of φ16.97mm is the outer diameter before rolling the thread on the thread rolling machine. After the lathe process, it is time-consuming to grind two steps outside the M131W universal grinding machine and the operation is not high.