The diameter of the drill bit selected in this table is aimed at easily knowing the diameter of the drill bit during tapping processing . It is selected based on the standard drill bit sold in the market. When using the drill bit, due to the shape, size and accuracy of the drill bit, The material being drilled, etc., has a great influence on the size and accuracy of the drilled hole. Therefore, use the drill diameter in this table. If there is any improper point, the drill diameter should be changed appropriately in the actual situation.