Metric System??
Can any one explain me what is metric system in a easy way??? getting confused in this... does 5M thread means 5mm thread diameter????
thanks in advance
3 Answers
The "M" designation for metric screws indicates the nominal outer diameter of the screw, in millimeters (e.g., an M6 screw has a nominal outer diameter of 6 millimeters). Wiki.
As Mihail pointed out, the 5M designates the nominal outside or inside diameter of the thread. Whether it is outside or inside depends on if you are working with a nut or a bolt. Keep in mind that these are "nominal" dimensions, don't expect a bolt or nut to actually measure 5mm.
In additional to the diameter, the pitch would also be listed. Maybe like M5 x 0.8
The pitch is a measurement of how fine or coarse the threads are. Smaller values are finer.