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Ways to *REALLY* erase a hard drive?

Discussion in 'Electronic Design' started by Greysky, Feb 10, 2005.

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  1. Greysky

    Greysky Guest

    I recently had a 80 gig Maxtor hard drive die on me. Though it was still
    under warranty (just) I decided a much better use for it was to turn it into
    a show-and-tell for the local elementary school kids. I finally managed to
    get the cover off the thing, exposing the inner platters. Someone told me a
    Torx 10 would fit those crazy screws on the cover plate - they were wrong.
    I had to drill them off. Now, I need to know a sure fire way of wiping data
    off the platters for good. The machine died before I could erase it inside
    the computer, so far I have a bunch of 'super magnets' which I dropped
    directly onto the platters and let them stay there overnight. Do you think
    this is enough? I would like to get them as deleted as I can possibly get
    them, but still be able to use the drive as a demonstration device for the
    kids. Thanks.
  2. Ian Stirling

    Ian Stirling Guest

    Security torx probably.
    Super magnets (AIUI) will not do a bulk erase od the disk.
    Thermite works for me.
  3. Surely the chances of it ever working again after being opened and
    having a few dirty fingers on the platters are negligible ? Who is ever
    going to try ? After you finish the show and tell, just remove or break
    a few chips on the controller board. This will ensure its pretty


    Adrian Jansen adrianjansen at internode dot on dot net
    Design Engineer J & K Micro Systems
    Microcomputer solutions for industrial control
    Note reply address is invalid, convert address above to machine form.
  4. Jim Thompson

    Jim Thompson Guest

    Maxtor's data recovery service routinely changes out the controller
    board. To remove data just use an AC electromagnet.

    ...Jim Thompson
  5. Guy Macon

    Guy Macon Guest

    That would be me.

    2ea 520MB western digital drives. Standard office environment,
    drive cover removed, running DOS scandisk in a looping bat file.

    First drive lasted 8 hours. Second drive lasted 4 hours.

    I expect that even a simple dust cover would extend this time,
    and that a newer, higher capacity drive would crash sooner.
  6. Guy Macon

    Guy Macon Guest

    Radio shack sells a powerful one, cheap. Get the videotape
    eraser, not the weaker audiontape eraser.
  7. DaveC

    DaveC Guest

    You must work for some sort of top-secret government agency. But spy's
    are everywhere in elementary school. Can't be too careful.

  8. John Larkin

    John Larkin Guest

    Just bend the platters a tiny bit.

    What's on them, anyhow?

  9. Mac

    Mac Guest

    I don't have any practical experience with this, but IIRC, there is a
    temperature above which magnetic materials become very free to realign
    their magnetic polarity. This temperature is called the Curie temperature
    or Curie point, I think.

    So, if you heat the disk material above its Curie point in the presence
    of a strong magnetic field (electro-magnet, maybe?) you should effectively
    render the disk unreadable.

    Good luck!

  10. Paul Burke

    Paul Burke Guest

    There are various Curie points, graded from korma to vindaloo.

    Paul Burke
  11. be carefull, we had a drive and when we removed the cover and was in the
    process of messing around with it the platter just shattered into a load of
    shards, it was like glass. Sonds strange I know but thats exactly what it
    was like

  12. doreme

    doreme Guest

    Think the Magdras point is what you need.
  13. Alan Turner

    Alan Turner Guest


    The platters on some newer hard disks are made of glass. I believe the
    later IBM DeskStar* (tm) series were among the first to have glass
    platters. I'm not sure what the advantage is to glass, but I'd certainly
    like to take one apart and have a look!

    * Sometimes referred to as "DeathStar" due to reliability issues. I've not
    had any trouble with the DeskStar disks I've used. Lucky me!

  14. Probably because that what it was.
  15. Al

    Al Guest

    Years ago, when reel-to-reel tape recorders were popular, there was a
    gadget called a bulk reel eraser. It completely wiped any information on
    the tapes. In essence it was just a giant electromagent that ran on AC.
    The fluctuating magnet field was suffiecient to totally erase the
    information and not leave a magnetic bias on the magnetic medium. If you
    can find one, you might be able to build one easily from a discarded

    Yes, and most of the screws are Torx. But they are also held in with a
    drop of some sort of glue to prevent their backing out. I've extracted
    platters from dozens of drives which I got at our town's recycling
    center. I do it mainly for the magnets. And the platters make neat
    coasters for your drinks ;-)

  16. Beware though, that the design of digital tapes, can make them much harder
    to erase, than the old audio tapes. I had an eraser of the type you are
    referring to. Had happily erased any number of audio tapes, then tried a
    DAT tape. It was amazingly resistant to this type of erasure (after ten
    minutes, it eventually became unreadable). The same is almost certainly
    true of the data on a hard disk.

    Best Wishes
  17. John Larkin

    John Larkin Guest

    Well, then bending would take care of the data recovery problem.

  18. Guy Macon

    Guy Macon Guest

    Like I said before, radio shack sells them. They are called video
    tape bulk erasers now.
  19. What about phall? Many Indian restaurants won't serve it to people they
    don't know, because the effects on an inexperienced eater upset the
    other customers. Symbol - five chilis.
  20. Barry Lennox

    Barry Lennox Guest

    Just a magnetic degausser works, but you need a reasonably powerful
    device. IIRC you require about 3500-4500 gauss for HDDs and DAT tapes,
    while most of the low-cost commercial devices are around 1000 gauss.

    There's some info at

    I used to use one that look a little like a microwave oven, and the
    manufacturers blurb stated it used a charged cap dumped through a
    coil. Never saw a schematic or got to look at it's guts however.

    Barry Lennox
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