In article ,
"Michael Koblic" wrote:

"Carla Fong" wrote in message
...
Hi all -

In a brief period of boredom we wrote a small application to convert
decimal values to fractions.

(If anybody wants a copy, email me at carla dot fong at verizon dot net.
The 'reply to' on this message is spam-trapped) Runs on Windows.

It also calculates the next larger 1/64th inch drill for a decimal value -
handy if you read the size with a caliper and want a fractional drill bit
to match.

This brings up my question: Is there a way to calculate the decimal inch
sizes of letter- and number- denominated drill bits, or are they ad hoc?


I do not know about calculating. I have this chart stuck to the wall next to
the drill press :-)

http://www.gearhob.com/eng/design/drill_eng.htm

There probably is a simple mathematical rule used to generate the drill
diameter tables. I don't know the rule, but I would guess that it is
documented in the standard ANSI/ASME B94.11M-1993 (or earlier issue,
which may be free), which is cited in Machinery's Handbook as the source
of the tables.

Joe Gwinn