Sander / Grinder From an Old Hard Disk

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About: I like to build, scavenge material from junkyards, tear up machinery and stuff.

Hello ladies and gentlemen, and welcome to my new Instructable.

I will quickly cover the main steps on how to make a simple sander / grinder using a hard disk.

That's kind of out of focus, but look at those sparks. Yummy scorching particles.

Step 1: Open It Up

I chose a 7200rpm HDD. No particular reason, any will do.

The tool will be powered via the Molex connector, I adapted a power supply some time ago, which now comes in very handy when I want to move this little beast around, click here to see it: Molex PSU.

Simply open the hard disk with a Torx screwdriver (usually, size 7 and 8 are ok).

Remove te heads and the internal electronics, only leave the motor and the plates.

Cut a disc of sanding paper the same size of a plate.

What you have to do is to rearrange the plates and the spacers so that the sandpaper has the sturdiest base. I personally stacked them this way: plate - plate - sandpaper - spacer - holder.

Step 2: It Already Works Well, But...

...if you want to use it at the top of its capabilities, cut the base and the lid as shown in the pictures.

The lidded part allows to grab the sander and use it on objects, as the "blade" is now unobstructed by the frame.

You may also add a PCB protection. As you wish, it works anyways.

Step 3: Unexpected Problem

There is a little problem, the hard drive shuts itself off after a minute to save energy. I don't know how to prevent this, so I added a switch on the 12V line that allows me to turn it off and on without losing spinning momentum.

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    19 Discussions

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    hl1ayw

    1 year ago

    Hello When I remove the head It does not turn with molex connector powered.

    So I found 3 pins from motor powered directly to two of three pins.

    However it turns and a little stops right away. What happens?

    Is there anybody to teach me why it is?

    1 reply
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    SussoGobbinohl1ayw

    Reply 1 year ago

    It's probably due to some protection on the controller, sensing something is wrong and preventing the motor to run.
    The motor can't be powered directly, it needs the circuit board.
    Try another HDD, I've never experienced this problem so far.

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    dadu2007

    2 years ago

    El interruptor va en cable amarillo (12v) y el negativo cual es?

    3 replies
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    SussoGobbinodadu2007

    Reply 2 years ago

    The switch only breaks the yellow wire, to interrupt the supply of +12V.

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    dadu2007SussoGobbino

    Reply 2 years ago

    Disculpa..No find a way to operate the disc without stopping after 10 seconds

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    nsiniard

    4 years ago

    wouldn't a button instead of a switch be easier to operate? I will let you know when I give it a go. thanks for this idea!

    6 replies
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    SussoGobbinonsiniard

    Reply 4 years ago on Introduction

    Hello, I opted for a switch because you can turn it on and leave it on while having both hands free!

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    dadu2007SussoGobbino

    Reply 2 years ago

    Te dio resultado con el interruptor porque a mi se me apaga en 10 segundos

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    dadu2007SussoGobbino

    Reply 2 years ago

    Hello, I run the switch , because it is for every 10 seconds

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    pfred2

    4 years ago on Introduction

    I cannot imagine hard disk motors have much torque. I suppose they spin at a pretty good speed though. I tend to like my power tools with a bit more power myself.

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    MikB

    4 years ago on Introduction

    The hard drive turns itself off after a minute because it will be
    furiously seeking the head back and forth trying to read the disk. The
    disk: Covered in sandpaper. The heads: Removed. :)



    Basically the feedback loop has been broken, so it has no idea how
    fast the platter is spinning, where the heads are etc. and so it shuts
    down and sulks.

    2 replies
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    SussoGobbinoMikB

    Reply 4 years ago on Introduction

    That's the reason, no computer that tells it what to do, and it just thinks "meh, I'll sleep".
    I think it's actually a good thing, because if I ever forget it turned on, it shuts itself off!

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    MikBSussoGobbino

    Reply 4 years ago on Introduction

    Even with a computer, it would stop spinning in short order. The drive needs the signals from the heads and the platter to be sure that the platter is spinning at the right speed, and to find where the heads are. If the heads were still on the arm, you'd get a "click-a-click-a-click" as it waved them back and forth looking for the platter. And sanding the heads down :(