Alan, depending on the application, you can usually get by with one set of drills or the other. This is especially true If your main purpose in drilling is to tap new threads. In metric sizes, the proper drill bit for a tap is the diameter minus the pitch. An m8 x 1,25 will take a 6.75 drill, for instance. 6.75 mm will convert to an SAE bit within a few thousandth if you have a big set of bits. 

Jim

On Jun 21, 2011, at 3:48 PM, Alan Felder <dieseldoofus@GMAIL.COM> wrote:

> What I have been looking for is a medium-size metal drill index box for
> metric bits - anyone have a source for that?
> 
> --
> Alan Felder
> Austin TX
> 82 Diesel Westy