Re: Hard Drive magnets.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Christopher Boden by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <chrisboden-at-hotmail-dot-com>
> 
> >Original poster: "Jason Johnson by way of Terry Fritz
> ><twftesla-at-uswest-dot-net>" <hvjjohnson13-at-hotmail-dot-com>
> 
> >I used were kidney shaped NIB (neodymium iron boron, I think) ones out of
> >an
> >old hard drive. They could lift 80 lbs of iron a piece.
> 
> I wanna see this drive :) that's a SERIOUS magnet, I've gutted 300Lbs hard
> drives (out of a 3990IBM and also an IBM AS400 mainframe) and never seen a
> hard drive magnet that could lift 80lbs (though they WILL give you really
> nasty blood blisters). I want a couple of those magnets....the fun I could
> have :)

	I have a magnet out of a scrapped IBM hard drive stuck to the side of
my safe at work, and have been unable to remove it.  Period.  Stuck too
hard to slide on the painted surface, and no way to get a pry bar under
it.  I'd guess the force of attraction at at least a couple of hundred
pounds.  Don't know the model of drive it came out of (was one of those
with enormous removable disk packs).  Our security department destroyed
a number of these drives, apparently not realizing that the information
was in the disks and not in the drive mechanism.  By the time I got on
the scene all that was left was this one magnet stuck to the inside of a
dumpster, but there had been at least a dozen others.....  Got the
magnet out of the dumpster by sliding it to the edge; can't seem to do
that with it stuck to the safe.

	I also have a number of those "kidney-shaped magnets" bought from ALL
Electronics which I'm pretty sure would give 80 pounds attraction to a
good, flat ferrous surface.  Can't pull them off at all, but have to
slide and pry.  I realize the force may be less than I think, as the
little buggers are hard to grasp......

	As for quenching arcs or sparks, the proper location  for the magnets
is such that the field they create is transverse to the direction of
current flow.  The spark will move "out of the field" just as a
conductor will move.  

Ed