[time-nuts] OT Prototype Boards

[Robert Darlington]

Machinists know that 1 inch is exactly 2.54cm or 25.4mm.  It's a
definition, not a coincidence.

-Bob


On Tue, Jun 25, 2013 at 10:17 AM, Bob Stewart <bob at evoria.net> wrote:

> Hi Hal,
>
> I had always used 25.4001 or .03937 to do my conversions.  So, I looked
> online and found the .039370078 and did the reciprocal.  It is, indeed very
> very close to 25.4.  If you google "25.4001 conversion" you can find lots
> of tables using that as the conversion factor online.  I don't know where
> the error came from or why it's quoted so regularly.   But, it appears to
> be the rounded result of taking the reciprocal of a rounded number.  Don't
> machinists use this number for conversion?
>
> Thanks for the discussion, everyone.
>
> bob
>