"Dave Hinz" wrote in
message ...
Building a project out of a piece of 4140
prehard. The local custom
metalcutting shop provided the steel. Problem
is, it's magnetic. Not
just a little magnetic, it's "you could use this
thing to pick up nails,
small children, and battleships" magnetic. I
asked them if they have a
demag ring, they don't (and were surprised but
will check their stock...
ok, great, but doesn't help me much at the
moment).

So how do I demag this sucker? I know that heat
would do it, but I
don't want to mess up my hardening. I know
mechanical impact can redue
it, but I don't know if that's one of those
"theoretical but not
practical" things, or if it'd work. So, simple
question - can I just
smack the (un-machined) end of this sucker with
a hammer a bunch of
times and get it down to tolerable, or do I need
to find someone with
degaussing apparatus of some sort, or am I SOL?
It's annoying, to say
the least, to have every chip re-attach itself
to the work, invariably
on the layout lines that I'm trying to see.

Thanks,
Dave Hinz

Electric motor rewinders have a test unit
commonly called a "growler". This was for testing
armatures and was basically a coil with poles
pieces. I used to use one to demagnetise any
rotating part of our equipment when working in the
oil well logging industry. Easy to use, we just
turned on the switch while some distance from the
part, moved close to the part and held it for a
while then backed away before shutting it off. It
was usually successful, though I heard that one of
the trucks had been hit by lightning and had to be
scrapped, as it not be demagnetised to an
acceptable level.