On Nov 25, 12:56*pm, Joseph Gwinn wrote:

The sizes will not be arbitrarily chosen, as there is money at stake. *

Correct.

The problem being solved is how to choose diameters such that the fewest
number of sizes will cover the needed range.

Maybe not; the original of the drill gage is a wire gage, and the
wire-drawing process is more likely the driving technology, not
the drill requirement.

From the look of the wiki plot, I would guess that if one plots log of
diameter against drill size (number or letter), one will get a roughly
straight line, although the segments will remain visible.

Drawing wire is done by pulling through a succession of dies, each
a little smaller than the one before. If you can narrow the diameter
by 20% on each pull, without unacceptable breakage or die wear,
that fraction will remain the same regardless of what the die
diameter is.

So, a wire-drawing plant starts with a few pounds of hot-rolled rod,
and after the first sizing die, calls the product 'zero gage'. Two
pulls
later, it's #2 gage, etc. Straight line on a semilog plot is exactly
what one expects.