John B. wrote:

There used to be a "rule of thumb" to always
use an adjustable wrench so that the force is
against the fixed jaw. I have proved this
rule myself. I was squatting down tightening
the bolts that held a large vise to a bench.
The wrench didn't fit in its proper
orientation so I flipped it over and pushed
against the movable jaw. I proved, at least
to my own satisfaction, that (1) an
adjustable wrench used in this manner will
slip, and (2) a broken nose Hurts!

Ha!

I've heard the rule and some people insist it
be adhered to even for fixed wrenches! Well,
I suppose the smaller jaw is the one that
corresponds to the movable jaw. But really
I think this is just something they have
brought over from using adjustable wrenches.

--
underground experts united
http://user.it.uu.se/~embe8573