Dear Denizens of the Porch,

I've come across a Rabone rule that has two scales on the top front; "Spanner"
and "Tapping".  The rule is stamped No. 27 but finding a Rabone catalog online
rule No. 27 scales are similar for 3 edges but not for the top front. The
tapping scale makes some sense in that each labeled increment is a bit short in
length of the indicated measure. So "3/4" is about 5/8", "2" is struck at about
1 3/4".  I guess this would be the diameter of a hole drilled to be tapped to
the indicated I.D., but again that's a guess.  I have no clue as to what is
going on with the Spanner scale. Marks in increments of 1/4 are spaced about
3/8" apart.  Between these marks are struck lines that are sometimes somewhat
centered in the interval, sometimes far from.  Maybe unrelated?  My internet
search has come up blank.  Does someone here know how these scales were applied?

Thank you,

Kevin in too warm because I'm not from around here Virginia.

photos here:

https://www.flickr.com/photos/188990335@N.../50219277551/in/album-72157
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-72157715463748903/
and here:

https://www.flickr.com/photos/188990335@N.../50219280826/in/album-72157
715463748903/">https://www.flickr.com/photos/188990335@N.../50219280826/in/album
-72157715463748903/

“Spanner” will be the opening of the wrench which fits a bolt or nut with that
diameter of thread.

In the British Standard Whitworth system, the wrenches are marked with the
thread diameter which they fit, not the actual opening.

Some early USS ( United States Standard) wrenches are likewise marked for the
bolt or cap screw diameter which they fit.

John Ruth

Sent from my iPhone

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

Do we have a date of manufacture by Rabone?  


and - does anyone else appreciate the typestyle used on old steel rules?  Rabone
I find to be particularly elegant in a functional way.  Laid alongside a modern
sans serif laser etched millimetric one the other day I had one of those brief
’the old tools have a fitness for purpose that is evidenced in the design and
the detail that has been lost in our modern age.


Richard Wilson
Near the North Eastern coast where a fret is blowing in to dispel the hot couple
of days.

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

Kevin dates the rule back over a 100 years, so we’re back in the era where many
’standards’ existed, and screws were still made individually in workshops.
Johns theory makes sense to me.  If you were hand making a nut and bolt from raw
steel (or iron) you might appreciate a bit of help.


As regards ’spanner’ - why, what else would you call the thing that spans across
the flats of a nut?    Those of us who started the industrial revolution would
look at a nut with a practiced eye and say to t’ lad “Ayup, gormless, pass us
summat that’ll span abaht seven eighths of an inch - and be quick abaht it or
they’ll get my fist rounf thi lugs”

And the gormless lad would take out his rule, measure the span of the spanners,
and select the right one.


It’s early - a little dialect word picture to start the day.  


from ‘every boys guide to becoming a Yorkshire engineer’ - 1893 edition. 

Richard Wilson
Yorkshumbrian Galoot.