Dave Hinz wrote:
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

You could wave a magnet in its vicinity.

No kidding -- I have successfully demagnetized screwdrivers with a
strong permanent magnet. Stroke it a few times with one pole, then
reverse the magnet and stroke it a bit further away. Keep doing this
until you're waving the magnet in the air well away from the part.

It _won't_ demagnetize the thing completely, and may not work at all for
complex shapes, but it should make things better.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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