Robert Swinney wrote:

You'd quibble over a difference of 0.001 inch between the two formula?

No. Not over 0.001 inch. No use arguing about a hair.

But what's the right drill (according to your formula) for:
(std) means this is the standard pitch,
(fine) is one of the fine pitches.

M3 * 0.5 (std)
M3 * 0.35 (fine)
M6 * 1 (std)
M6 * 0.5 (fine)
M6 * 0.75 (fine)
M10 * 1.5 (std)
M10 * 0.5 (std)

Pick any 7 and please answer with your formula.

Thanks,
Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...