In the past when I picked up an ordinary woodscrew, I used to look
at the head diameter and could usually guess what "number" it was.
If I had to measure it then the head diameter in millimetres seemed
to give me that "number" value.
Now I want to get some replacment screws by ordering online but
it's all metric and seems a bit of a muddle to me.
Is the head size of a woodscrew still a good guide to the shaft
diameter? The illustrations I've seen suggest it might not be. If
I can't use the head size to determine the shaft diameter then what
measurements should I use?
In the end I want to order some (metric sized) woodscrews similar
to the ones I have (the older ones are probably imperial). How can
I do this? I can take accurate measurements ofmy woodscrews using
calipers but how do I translate that into what I can order?