On Thu, 11 May 2017 10:47:10 +0200, Emanuel Berg
wrote:

John B. wrote:

In fact, using conventional wrenches it is
quite easy to actually break the shank of
a fastener without damaging the head at all.

Fixed wrenches do not damage the head. They are
faster, more reliable and more ergonomic than
adjustable wrenches and I dare say they pull
tighter or as tight in practice, using them all
day long.

It is possible in a test lab for a single bolt
it is possible to show an adjustable wrench
pulls tighter but in practice it is actually
the adjustable wrench that will round the
corners as the mechanic will get tired and make
mistakes. And one source of him/her getting
tired will be having to adjust the wrench all
the time

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!

--
Cheers,

John B.