On Monday, March 23, 2015 at 12:01:02 PM UTC-7, wrote:
... to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds.

A tape head demagnetizer (kind of a wand with a power cord) can
demagnetize by slowly pulling away from the object. If, however,
one switches it off instead of pulling away, it magnetizes any object
near its tip.

So, for something this small, I'd get a tape head demagnetizer and put
it onto a foot switch AC outlet.