Hack a Dead HDD and an Angle Grinder Disk Into a Small Tool Emery Wheel




Every x-acto knife, scalpel, chisel comes to a point where it needs to be re-sharpened.
Every HDD eventually fails.
Every angle grinder disk will eventually get too small to actually grind anything.

With all these three simple assumptions verified in the same day and quite a bit of frustration, I began this project.
To turn that junk that was piling up before me in something useful: a small emery wheel of sorts.

BEWARE: angle grinder discs are not meant for sharpening, they are meant for cutting: every disk shows a warning that tells you to make contact with objects only with the side of the disk; touching the surface of the disk with an iron bar will result in it shattering and splinters wil fly around and you'll get hurt.
However, an angle grinder packs much more power than an HDD elecrtic motor. With this setup if you push to much into the disk, it'll just stop spinning.

DISCLAIMER: as usual, if you hurt yourself following these instructions, that's because you didn't know what you were doing, and not my responsibility. Use gloves, eye protection, body armor, and if you're not sure how to do something, just don't. Don't risk it, and don't blame me if something goes wrong.

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Step 1: Open Up

Here we have our HDD.

First we'll have to locate all the screws: a couple of them will be sealed away under white or "warranty void if removed" stickers.

Find 'em and remove all of them.

Open up, you might need to pry it open with a flat screwdriver, since many HDD producers use some kind of gummy stuff to keep the HDDs airtight.

Step 2: Strip It Down

Now we'll have to remove everything we don't need.

let's begin by prying off the upper support for the heads mount.

Now, pushing with your finger on the copper coil you just exposed slide the heads off the disk[s] and unscrew the bearing with a large flat screwdriver. They'll come rigt off, but you'll notice that they still hang to the HDD body by a flat wire.

Unscrew the evntual screws keeping the flat connector down and pull hard to remove.

Unscreew the rare earth magnet and store it for future projects.

Unscrew the 3 screws that keep the disk attached to the motor, and set aside along with the small disk, then lift off the main disk.

Step 3: Add the Disk

The angle grinder disk will not fit on the bearing, so we'll just lay it on and screw the small disk back in place.

Step 4: Power On

now you need to get power to the HDD.

I used an adapter that I had lying around in my wiring drawer, but you can also power it up by shorting the green wire with a black wire on an ATX power supply.

so plug it in and watch it spin!

Step 5: Grind Away!

Here you have it. now you'll be able to sharpen scalpels, chisels, x-acto knives, regular knives, scissors, drill bits, coins, anything!

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    26 Discussions


    6 years ago on Step 4

    Be sure to check the RPM rating of the grinding disc. Most hard drives spin at 4200/5400/7200/10000 RPM. Do not put in a disc that is rated lower than the speed of your drive, really bad things could happen(disc exploding with shrapnel).


    4 years ago

    My HDD turns off after 24 secs; can I get some help on how to keep it running?


    4 years ago on Introduction

    I am wondering if it's only me, but when i try to grind something, i't lacks power or torque (i don't know the exact term and english is not my native language)...

    1 reply

    6 years ago on Step 5

    The comp you entered this in - you should have won - if only for the ability to sharpen blades and drills.

    A really good use of damaged or worn out items into something still useful.

    This is not just a good build but a money saving brilliant one.



    6 years ago on Introduction

    !!I would be careful that no metal dust gets into the electronics!!


    6 years ago on Introduction

    I have the same failed hard drive LOL might have to try this!


    6 years ago on Introduction

    Nice job artifeffe, nice ible.
    I occasionally do small bass and balsa wood sculpting - I could see using 2 or 3 of these, with fine, medium, and course sandpaper!
    Are these HDD motors any more powerful than computer fan motors? Obviously, you don't need the precise speed control... If one used a (surplus) fan, made the disc a little smaller than the fan duct, it could suck the debris into a containment bag as the piece is ground or sanded...(!)


    6 years ago on Introduction

    An interesting idea. Angle grinder disks are pretty rough though for sharpening.
    Have you thought about removing the disk from the drive and putting self adhesive sanding paper on it, cutting it to size. Then you could re-install the disk and use that as the grinding surface and you can replace the paper with different grits if you want to.
    Just a thought.

    2 replies

    Reply 6 years ago on Introduction

    I had actually thought of that while writing this ible, and is an awesome idea, it's just that my goal was to use up the disks.
    And it dawns upon me now, HDD disks are way under the edge of the body: you ouldn't be able to reach them with a long item like a knife unless the HDD housing was properly shaped.

    BTW excuse me if I sound rough, that is not my intention, it's just that english is not my primary language. I accept corrections very well thogh!


    Reply 6 years ago on Introduction

    No worries, you did not sound rough in the least.
    No offence taken.
    And it was not my intention to correct you, I was just tossing out another Idea, that is what this site is all about..
    Keep em coming.


    6 years ago on Introduction

    Great idea.
    I think you can cut a piece of the HD frame an put a wood saw instead a disc to make a cutting table.


    6 years ago on Introduction

    Hey , good job, we could mate this instructable with my one : https://www.instructables.com/id/Recycled-HDD-Powertool-Disk-of-Prometheus/ to make a super combo-tool!


    6 years ago on Step 4

    Hi and thanks for the great instructable !!

    ive done this to a few HDDs but havent found one that stays spinning - stays spinning continuously until i remove power !

    Have you managed to solve this problem by any chance ?

    Ive 4 of these HDDs, all different manufacturers and they all spins up, slow down, spin up, slow right down, spin up again and then stop...

    Not until i remove the power and the re-insert power to any of these HDDs will they start up and start this annoying cycle again, none of my HDDs actually stay on at top speed !

    The speed is always as if the HDD is trying to read the platters so i kinda gave up on this idea as a small hobby knife sharpener lol !

    Do you have any of these problems, if so, how have you overcome them (if at all, lol ?!?) ?!?

    many thanks in advance !


    6 years ago on Introduction

    Nice idea on this...I will definitely add it to my workroom. Just something I thought though, besides the glasses as mentioned earlier, as best you can, center the disk before tightening. this will lose a lot of the vibration.


    6 years ago on Introduction

    there is one common issue i have encountered with HDD's they stop turning after around 20 seconds. the motor just stops. any suggestions?

    1 reply

    Reply 6 years ago on Introduction

    not all old hard disk can be used, you have to choose the ones that will continue running without the board.. check my instructable too.


    6 years ago on Introduction

    Very nice idea, I recently saw a picture in a HackADay link share, of a rotary sander made out of a HDD. I assume the guy just glued/taped the sandpaper onto the platter. I also see a few people mentioned doing the same below. You guys are onto something here, some relatively silent rotary grinders for a DIYer. I will definitely build one!