Repurposing old HDD Components

hdd-stepper

[IronJungle] had an old hard drive taking up space in his workshop, so he took it apart and wrote in to remind us how useful these old pieces of hardware can be. Aside from offering up incredibly strong magnets and donut-shaped mirrors, HDDs also come with a reliable stepper motor in tow.

He pulled theold drive apart, wiring up two of the stepper motor pins to a pair of the drive’s header pins. This allowed him to easily access the signals produced by the stepper simply by hooking up a small JST connector to the back of the drive.

From there, he can use the drive for any number of purposes. For the sake of discussion, [IronJungle] used it to flash an LED as seen in the video below – something he willingly admits is no great feat. However, stepper motors can be used for in a wide array of projects, both simple and complex. Be sure to share your favorite use for salvaged HDD motors in the comments.

30 thoughts on “Repurposing old HDD Components

  1. My reactions were about as follows:

    … Hey I wonder what new purpose for HDD components someone has come up with. Another POV clock? a mechanical TV? Interesting!

    … They’re talking about stepper motors, hmmm they must be working with a REALLY early generation of HDD’s like my first BASF 10MB drive. Cool!

    … Oh wait, they’ve got their definitions mixed up, they mean the spindle motor. Alright, so what’s going on?

    … Well, apparently not much yet… This is very much a work in progress. Guess I’ll have to come back later :-)

  2. I always wondered if old hdds could be used as a flywheel storage medium for reclaiming electricity instead of battery or capacitor storage, but I didn’t think that the relatively low rpm of these disks would make it a worthwhile endeavor…

    1. You can run the spindle motor with a hobby ESC, so I suppose you could spin it up at least to it’s rated speed, 7-10k RPM, but I’m not sure how well you could extract the stored energy with such an ESC, most of the hobby type aren’t designed for energy recovery. You’d have to add a second circuit for that I’d suppose.

      You could increase the storage potential by replacing the platters and spacers with a stack of platters from other drives, but you’d probably have to rebalance it (maybe a wireless accelerometer could be placed on the hub to determine where the imbalance was).

      1. regenerative braking would be recovering that energy. I don’t know about tiny ESCs, but I wouldn’t be surprised if there was one that did regen braking.

    2. I think modern drives actually do this. They use regenerative braking to gather enough energy to safely park the heads in case of sudden power loss. In a robot, the platters could serve as both a gyroscope and a very small emergency backup energy source.

      For any real power applications, the platters would either have to be much heavier, much larger in diameter, or spin much faster.

  3. I took a pile of dead drives, ripped the magnets and voice coils out of them, put the mags on 1 saw blade and the coils on another, and built a small generator.

    Proof of concept, really… The mags are strong enough (especially if you stack enough of them together), but the coils can’t carry enough amperage to be really useful.

  4. Messrs Mike, Caleb and Brian of HAD – as well as my fellow readers –
    I would like to request that what may be the first ever “Ask HAD” request for assistance.

    I would like very much to come up with a way to measure (in PPM) volatiles in drinking water, but will settle for arsenic, lead and whatever else is easy to pull out. I would like to do this by taking hourly samples, in a way that would allow for easy data collection… and publishing.

    As local aquifer contamination/destruction becomes a standard business plan, I think it might be important for people to be able and monitor their water’s potability.

    Most municipal water systems publish results based on a single sample, which is fine except that it’s easy to wait for a day when the quality is good to take that single sample.

    I wish to open source those measurements, to the extent that anyone who has a little disposable cash can install a water system monitor in the same way that people install home weather stations.

    I know a lot about a lot of things, but my knowledge of water quality analysis is limited to a few projects concerning flow and particulate, ph and dissolved oxygen. As far as chemical contamination and spectral analysis, I don’t know jack.

    Anyone have any ideas about “How to measure contaminants” in water short of manually collecting and processing a sample and then working my way through a barrage of various micro-chemistry experiments?

    There may be a reason this isn’t done already.

    1. Look up arduino based water quality testers.

      http://publiclaboratory.org/tool/water-quality-sensor

      should be a good jumping off point.
      I made a kinda all-in-one for a friend that runs an oyster farm, but it was mainly used to check biomass,light,o2,n co2 for the algae to feed the lil oysters. Aside from a sequencer, it was my third project on an avr and the sketches were highly useful and pretty easy to customize, even tho I suck at code lol.

      Good Luck :)

    2. I would like to request that what may be the first ever “Ask HAD” request for assistance.
      I take it you haven’t found the forums yet.;)
      From experience, there’s some very helpful people who hang out there.

  5. Salvaged HDD motors can make for good bearings with very low play. Here’s one mounted in a wooden base next to a servo. It became one of the joints of a robot that waves crayons around in a menacing fashion.

  6. For the record, very old (pre-1992, at least) hard drives actually did contain stepper motors for head positioning. The 20 megabyte (yes, 20,000 Kbyte) hard drives that sat under Mac Plusses were a decent source. If you spot one at Electronics Recycling Day, snag it. :-)

  7. Yeah! My plastic drum kit has on the side a 10MB drive with the platter gone and spindle extended with a knob. The head positioning motor is also knobbed and provides the scratch-woop sound that with deft fingering can almost talk. The platter motor has on the backside a flat rotor so there is flywheel mass. This makes the woop octaves lower in tone, a sub throbbing bass! I have heard the patch in current dance tunes. This motor also has a switch to short out one side of the delta winding giving a shorter decay, about a quarter spin time.

  8. Kasap, in “Magnetic Information-Storage Materials” in Springer handbook of electronic and photonic materials, indicates that modern hard drive platter top coats of 10-50 nm thickness typically employ various mixtures of Cobalt, Ruthenium, Iron, Chrome, Titanium, Zirconium, Palladium, Platinum and Niobium.

    If you wash your hands after handling and resist the urge to lick the platters, you should be OK.

  9. My favorite part of old drives is the head positioning system. Those powerful magnets with the voice coil between them can work to drive a speaker cone in and out for a fairly efficient speaker.

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