"Jeff Wisnia" wrote in message
...
My inquiring mind just asked me why the preponderance of threaded
fasteners, jar lids and stuff have right hand threads. (Both above and
below the earth's equator. G)

Somewhere I learned that "clockwise", like the hands of a clock, comes
from the direction of rotation of the gnomon's shadow on a sundial, in
that part of the earth where sundials were first used. But I can't see a
screwy connection to that, other than it taking less time to write
clockwise than counterclockwise.

Is there any history of a society which used predominately left hand
threads?

I experimented with a torque wrench and a big socket I could wrap my
fist around to see if my dominant (fancy word for my right) hand could
exert more twisting torque in one direction or another, and didn't
notice much difference.

Comments? (Other than informing me that I obviously have too much time
on my hands these days.)

Jeff


--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"My luck is so bad that if I bought a cemetery, people would stop dying."


Just part of the standardised thread forms that Whitworth introduced into
19th Century manufacturing. Why he chose right and 55 degrees for the
thread form instead of left and 54 degrees - God knows. Maybe
something to do with the direction of rotation of the early steam
engines and the right hand thread being less prone to coming loose?