M bolts

[Radar]

Please forgive my ignorance, always worked on the 'no-such thing as a silly question' principle myself - please edumacate me. Ta in advance

Now I know that M stands for mm and the number is the diameter of the bolt - is that the diameter with or without threads.


Anything else I need to know about bolts? (Apart from Titanium ones are nice but expensive)

 

[andy.l]

with threads

 

[Radar]

Thank you.

Something else added to the list of useful thingsto know, but, wasn't taught at school

 

[Andy R]

Well, the "M" indicates that it is a metric thread and the number is the nominal diameter (in millimetres) of the screw or bolt. The actual diameter measured across the threaded portion may be slightly less than this however, especially if it is a rolled thread.