The strong magnetic field might destroy the heads themselves.
They are tiny and use very small wire in the loop.

Martin

On 5/25/2011 6:52 PM, wrote:
On Wed, 25 May 2011 17:55:35 -0500, Ignoramus23924
wrote:

On 2011-05-25, Bob La wrote:
id wrote in message
...
I have a little industrial demagnetizer from a grinding shop. Can this
thing erase contents of hard drives securely? Or the magnetic field is
not string enough? I have a pile of old HDs awaiting destruction.

THe alternative is my press, which is more of a PITA.

Thanks

Reminds me of the ex girlfriend of one of my buddies back when Radio Shack
had a real computer push. She was their computer guru. Usually she asked
me or my buddy for help with anything as we were real computer nerds back
then. One day she didn't ask us when she decided to erase an old Seagate
MFM hard drive with a mag tape bulk eraser. When she powered it up you
could hear that drive screaming 4 shops down the walkway in the mall.




Hard drives have very powerful magnets in them.

i
Yes, but the flux of the head positioning magnets is very carefully
controlled so that NONE of it flows through or across the platters,
and NONE of it influences the read and write heads. The flux of those
strong magnets is concentrated through the gap where the "voice coil"
actuator armature works.