M3 threaded hole. The bottom should choose large diameter drill bit
The bottom of the thread hole of the above M3 is the standard diameter of the drill bit made of ordinary materials. Of course, the actual production operation because the M3 screw mechanical properties of various materials is not the same as the processing of the material properties through appropriately adjusting, processing, such as M3 stainless steel threaded hole, must be to increase the diameter of the bottom hole processing, because the mechanical properties of stainless steel and ordinary materials are not the same. Stainless steel material hardness high, heat dissipation is poor, the reason of higher plastic, bottom diameter with a diameter of 2.7 bits. So in the actual operation, the operator should be through different material properties, adjust the threaded hole diameter of M3, so as to prepare for the next tapping.
The thread hole M3, bottom diameter of drill processing is required to choose:M3 takes 0.5 of the coarse thread, with a diameter of 2.5 bit.M3 takes 0.35 of fine thread, with a drill of 2.65 in diameter.
What do you not know about screw diameter reduction? M3 the pitch is 0.5, that is, 3-0.5=2.5.. If it is a piece, it can be larger. Choose 2.55 to 2.6 of the drill bit. All other materials are 2.5.
