GG’s :

Richard wrote:
> “Now THAT is a fascinating snippet that’s new to me.  Someone made a rule that
bears the sizes of wrench openings needed.  “

To which inquiring Galoot minds immediately ask “Why?”

Best I can theorize is that this rule is for someone who taps custom nuts and
perhaps also makes custom bolts, which he measures to length with the scale.
That’s the only reason I can think of to put the “Tap Drill Size” and the
Nut/Bolt Head Sizes on one handy reference rule.

Anyone got a better theory than this late-evening SWAG?

Circa 1980, a Welsh friend had some British “spanners,” as he called them,
marked with the true size and the letters “AF”  for “Across [the] Flats.”  These
represented a departure from Whitworth practice.

+1 on the opinion that older rules have more-elegant type styles.

John Ruth