We have a bigass magnetic degauser, for erasing data tapes at work. You turn it on, and spin the tapes slowly for 30 seconds, and it erases them. Works awesome on tapes. (We do periodic checks to be sure no data is left).

I tried it on a hard drive once... first, the drive was ripped out of my hand, the magnet took me by surprise. I turned it a few times,hard as hell to do, and the drive got REALLY warm.

Once I was done (did two 30 second passes on it) I popped in back in a PC. Some minor corruption, but a good 95% of the data was just fine. And this degauser is basically a giant electromagnet. Didn't do squat compared to what I thought it would.

Tony

The degausser was acting like an induction heater to the HDD case. Barely any EMF was getting into the drive itself.

What you could do is fire the drive a few hundred miles into space so that it is exposed to raw solar radiation. All those gamma rays bombarding the HDD plates should erase everything just fine. Make sure to wear a lead-lined hazmat suit with your catcher's mit as the drive may become radioactive.