Joe Pfeiffer wrote:
Beryl writes:
Joe Pfeiffer wrote:
It's hard for me to imagine this making a significant difference.
A chain wrench, strap wrench, oil filter wrench, pipe wrench,
vise-grips as in the picture, etc., are made to work well in one
direction.

Many of the wrenches you've described -- in fact all but vice-grips --
are indeed designed so that turning in the "right" direction makes them
grip substantially tighter. Not true of vice-grips,

Use vise-grips the wrong direction, and they practically fall right off
the fastener and pop open. At least, mine do.
Look at the movable jaw in the picture posted. Turn the tool the correct
way (left) and the jaw is wedged closed, tightening around the nut. Turn
the wrong way, and the jaw is forced open.

and really doesn't look true of a nut in a clamp (in this case the clamp is the vice-grips,
of course).

The nut in this homebrew stud extractor isn't in a clamp, it's the
clamp. It's an extension of the jaws, part of the tool.

And if the nut _still_ turns on the stud, some lapping compound on the
threads could gain the extra bit of friction to make it work.