Topic: converting wire gauge numbers to metric dimensions.

[hymodyne]

I'm looking at super small drill bits at the hardware store, and they are sold by their wire gauge size. How do I convert these numbers to MM's? Specifically, How do I select the proper gauge measurement to match .40 to .45 MM?

hym

[SteveD CB500F]

Try somewhere like this:

www.roymech.co.uk/Useful_Tables/Wire.htm

So 0.416mm = 27 guage,  0.457mm = 26 guage

[Bodi]

Are you sure they are wire gauges?
Normal American twist drills come in 3 ranges; fractional - generally available from 1/64 inch to very large in 1/64th increments, number drills from #80 (smallest) to #1 (largest), and letter drills A (smallest) to Z (largest). Number drills start really small and go to just under 1/4 inch then the letter drills go up from there to roughly 10mm.
The numbers are not wire gauge sizes.
There's a decent list of sizes here http://shopswarf.orcon.net.nz/drills.html but I'd do the metric conversion myself, the inch measurements shown are accurate.

[Paul]

0.40mm = 0.0157" = Drill No.78
1/64" = 0.0156" = Closest fractional drill to .40mm
0.42mm = 0.0165" = Drill No. N/A
0.45mm = 0.0177" = Drill No.77

Letters start from 5.94mm and up
I know all this from memory