Recycled HDD Powertool (Disk of Prometheus)




About: M.H.Kabir is a green geek who likes recycling and loves instructables and DIY among other things such as microcontrollers, embedded systems and photography. He has done many DIY Green tech projects!He is a s...

UPDATE 09/04/2011: Hey guys, I have entered the Disk of Prometheus in the Green Living and Tech. Contest, Please VOTE for me!!

In my last instructable related to recycling old HDDs, I had designed a sander from a junked HDD for as little as $5. But, the old design had its limitations and i had got a lot of people writing to me about improving the design to increase its usefulness. You can find the old instructable here

The older HDD sander had its motor still attached to the HDD base, thus limiting its use. In this instructable, we're going to design a power tool using an old hard disk , which can not only do sanding, but also cutting, polishing(buffing) and it may also be equipped with a diamond blade to cut glass.
The HDD motors spin at a very high RPM, but do not have much torque,but once they get into full speed('bout 7200 RPM) it is enough for our grinding/ sanding/buffing etc. purposes.

WARNING: The HDD is not a plaything. The platters spin at a very high speed, making it easy for the sander to rub your finger raw. I am not responsible for any damage you do to yourself or to anyone else near you.

Step 1: Materials Needed

For the project we are going to need some cheap stuff. The list is pretty much same as the old HDD sander with a few additions.

  • A junked HDD(needs to spin up!!)
  • A Woodenruler
  • Wires (single-core preferred)

A wooden ruler may be difficult to come across nowadays. So, a piece of wood with the same dimensions will also suffice.

Optional: (for more info. go to Step 7)
  • Sponge
  • Diamond-edged Blade
  • Sand Paper
  • A brushless ESC like the one here (Step 8, Part 2)

  • Torx Screwdriver set
  • Power Drill
  • Soldering Iron
  • Soldering hot plate(optional)

Step 2: Diassembling the HDD

Start by peeling off all the stickers on the body of the HDD. Particularly the ones with "WARRANTY VOID IF SEAL IS BROKEN"

This will make all the Torx screws visible.
Unscrew all of them, on the side with the steel shield which protects the HDD.Carefully open the screws on the PCB side(other side) and remove the PCB for now as we will need it later.

Even after you unscrew all of the screws, it might seem as if the shield is still attached to the body. Inserting a flat blade screwdriver into the gap, pry it open, very gently.

After doing this, put the shield away and behold the guts of an HDD.

You will see 3 things. The HDD platter, the actuator head and the powerful rare-earth magnet. Pry away the magnet from the body and keep it for future projects.Also, slide out the actuator head and also store it.

Unscrew the platter screws so that the motor is exposed. There is a spacer between the motor and the platter.Store this also. The final step is to unscrew the motor from the HDD body so that we can fit it elsewhere.

Step 3: Assembly: Drilling the Holes

The first step in assembling our to-be power tool will be to drill holes according to the following plan:

We will drill holes for the motor and for the controller/driver on each side of the ruler. This step is pretty much self-explanatory. I just recommend you use a power drill with wood-cutting bits. Most rulers are a type of compacted MDF or compacted sawdust and you shouldn't have any problem in drilling right through.

Step 4: Assembly: Soldering

Now we need to solder the controller and the motor by using some wire. I recommend single-core wire. There is not much to write about this step - all you have to do is to solder 3 wires to the controller and the other ends to the respective motor contacts.

The pictures below explain this step thoroughly.

BTW, my soldering is not that messy. I just melted the solder onto the terminals, clipped the wires to the PCB and put it on a hot plate so that the soldered joints self-centered.

Step 5: Assembly: Fixing Everything Into Place

Now that all the drilling and soldering is done we can finally attach everything to the base. This step is very simple.

First we will screw in the controller PCB. You can use the original Torx screws for this purpose. After that you can zip tie the wires to the base to make it firm.

Now is the tricky part. We will need to zip tie the motor to the base. You may wonder why don't we just screw it in using long screws, but the zip ties are there to absorb vibrations. They cushion the motor so that vibrations are not transmitted to your hands. They act a bit like shock absorbers in a car .

Also they don't fall off like the screws, which I had used initially but could not withstand more that 2-3 spin-ups before they fell off or got so loose that the motor was close to flying off.

The pictures show you how to use the zipties.

After the motor is attached to the base, we can attach the platter to the motor. Remember to use the spacer which we kept away in step 2 and attach all the screws to prevent any damage when the motor spins up.

Step 6: Power Considerations

If you use your power tool on-bench, an ATX power supply with no modifications will do OK, but if you work a couple of feet away from your PSU, you need to extend the power cable by using a male and female molex/SATA connector with a long cord in between. Remember to use heat-shrink tubing at the joints.

OR, you could just buy one according to your needs from here

Now, that isn't the DIYer attitude,is it??? So I built my own 10ft long extender cable for the power tool.

Tip: You need to short the Green Cable on your PSU to any of the GNDs to make it power up.

Step 7: Tool Blades

The interchangeable nature of the HDD power tool is what makes it suitable for a range of applications. The following blades can be attached to the platter for different purposes.

Sanding Blade:

Same as the old HDD Sander. A Disc of sandpaper fitted onto the platter with or w/o glue. More info here

This can be used to sharpen knives too. Test results same as old HDD sander.

Diamond-edged Blade:

You can sandwich a diamond edged disc cutting blade as shown here to turn your power tool into an HDD glass cutter.It could also be used to cut traces on a PCB.I have not tested this yet. Waiting for my blades to arrive. You can get diamond-edged blades here.

You have to fix them as shown below. You will need another platter. HDD motors need to have a long life-span so they have ultra-high quality precision-balanced bearings making it absolutely perfect for our purposes.

Polishing/Buffing Attachment:

You can attach a sponge to the platter using water-soluble glue/screws to use our tool to polish surfaces.

More attachments to come soon.If you have any suggestions, leave them in the comments

Step 8: Troubleshooting

If you have any problem in starting up your power tool for the first time, try these steps:

1. Check solder joints on both the motor and controller for short-circuits. If found,clear them and try again.

2.If the controller gets very hot /smokes/ignites, you have a short somewhere and I am sorry to say that your controller is fried. For info on how to solve this, scroll down.

3. Make sure that the PSU is functional and the green wire/pin on the PSU is shorted to GND.Replace if PSU is faulty

4.Check the controller itself if it is working by using another motor if you have one/ replace controller.

5. If the Motor spins up ok, but turns off after 3-4 minutes, scroll down.

6. Check your PSU to controller extension cable >> Step 6 (if used)

1. What to Do if your Controller is Fried/Smokes/Catches Fire:

Turn off the PSU immediately and give the controller a dousing in FRESH(non-saline) water, to extinguish any flames.

Next, You could either replace the controller from another HDD


You could get a brushless ESC(Electronic Speed Controller), those used in R/C boats, aeroplanes etc. and attach it to your motor.

The + and - of your ESC should go to a 3.7v power supply, or according to the ESC's input specs. and the outputs to the respective motor terminals.The PWM terminals can also be attached to the same power adaptor if you don't want speed control.

Cheap ESCs available at / any other R/C hobby website)

About ESCs you can PM me for more info. on how to attach them, etc.

5. What to Do if the Motor spins up OK, but turns off after 3-4 minutes:

There are a row of contacts on the HDD controller's PCB. These get connected to the actuator head. Some newer 'smart' HDD spin up, but once they realize that they have no parts, they again spin down. Fortunately my HDD for this instructable was dumb enough to keep spinning , if yours aren't you could:

Try shorting some of those aforementioned contacts. One of the contacts are bound to restart the HDD. If one does restart the motor, bridge it using solder to keep the motor running. If the controller goes up in smoke, use the mentioned solution below, using the brushless ESC.


Keep the actuator head on and attached to the controller PCB


Snip of the actual head and just keep the connector, if that works


You could get a brushless ESC, those used in R/C boats, aeroplanes etc. and attach it to your motor, and remove the original controller completely.

The + and - of your ESC should go to a 3.7v power supply, or according to the ESC's input specs. and the outputs to the respective motor terminals.The PWM terminals can also be attached to the same power adaptor if you don't want speed control.

Cheap ESCs availible at / any other R/C hobby website)

About ESCs you can PM me for more info. on how to attach them, etc.

An instructable is coming soon on how to use the Disk of Prometheus with a brushless ESC and with speed control. Subscribe to me for updates!!



    • Gardening Contest

      Gardening Contest
    • Woodworking Contest

      Woodworking Contest
    • Classroom Science Contest

      Classroom Science Contest

    25 Discussions


    7 years ago on Introduction

    As cool as this is, I wonder about safety with such a thin piece of wood as a mount. How can this be improved to protect the user from a shattering drive disk if and when the handle breaks? Commercian sanders have covers on at least the back side to help protect from flying shards if an accident occurs.

    Any ideas anyone?

    8 replies

    Reply 7 years ago on Introduction

    There are two types of disk platters - glass based and aluminium based - if I am correct. Using the alluminium one would not shatter. If I am correct??


    Reply 7 years ago on Introduction

    Do you know a good way to tell whether your platter is glass or aluminum?


    Reply 7 years ago on Introduction

    get a magnet and run it across the surface, if it's aluminium it will resist you motion.


    Reply 7 years ago on Introduction

    Nope, aluminium in non-ferrous, so it is not attracted by a magnet, due to the molecular structures that it forms. No magnetism, no resistance


    Reply 2 years ago

    All electrically conductive materials do
    resist a moving magnetic field. The material does not have to be
    ferromagnetic. The physics behind this is that a changing magnetic
    field induces a current in the conductive material which is immediately
    shorted out by the conductive material.

    When dragging a magnet by
    hand to determine whether the material is conductive(metal), a powerful
    magnetic field will product a more noticable effect; however, an aluminum disk platter is very thin and so the effect will be difficult to notice.

    The energy
    provided by the moving magnetic material becomes heat in the conductive

    See induction heating article at wikipedia for more information.


    Reply 7 years ago on Introduction

    Won't a glass one do that, too, if it's coated with something metallic, which it probably is? Or is the thickness of the coating not enough to resist the magnet's motion?


    Reply 7 years ago on Introduction

    the coating would to some degree attract the magnet, but by wiping a magnet across the surface the interaction between the magnet and platter; if aluminium should produce a breaking force and glass should not, although im not sure if the coating will act as some sort of shielding, if you have a chunk of aluminium (most hdd are cased in aluminium) you can feel this magnetic interaction for yourself and hopefully feel the same on the platter.

    well i just tried it myself, one platter was out of the disk (was going to use it for fs mirror) and had no feel of force, the other one that was still attached did, but was quite weak, both had no surface attraction either, so in conclusion, it would be quite a tough call, i think ones glass and the other aluminium, but not 100% sure by any means.


    3 years ago on Introduction

    hey, I love the name of the tool and the concept, would you be okay with people such as me putting this tool, or it's name in other media, such as video games, books, and such, with full credit of the concept, name, and everything else concerning it to you?


    5 years ago on Introduction

    dont 4 get the plastic types as well. ive run into those as well


    7 years ago on Introduction

    Have you actually sanded anything with it?

    Cool idea, but me thinks there is no way that little motor will have the torque to sand anything. 7000RPM is super overkill for sanding, so what this needs is some gearing. That will also increase it's torque a bit.

    RPM is nothing without torque: there is another instructable about a tesla turbine that spins at something ridiculous like 60 000 rpm, but the guy holds the shaft between his index finger and thumb and brings the turbine to a halt.

    3 replies

    Reply 7 years ago on Introduction

    My angle grinders are 10,000 RPM so you were saying? Yes they have sandpaper and even flap discs too.


    Reply 7 years ago on Introduction

    What i'm saying is that your machine can run at 3000RPM, 7000RM 10000RM it makes zero difference in the ability of that machine to cut or grind anything. That depends on the power/torque of the machine. As I said telsa turbines can 60 000 RPM and you can bring that engine to a stop between your index finger and thumb. The reason is it has almost no torque. I'm just saying talk about RPM's is irrelevant. What can this motor do in terms of actual power/torque? If it's previous job was just to spin a aluminum disk at high speeds with not real resistance or work needing to be done, then I doubt it will be any use for this application, unless you invest some serious attention to gearing!


    Reply 7 years ago on Introduction

    Surface speed is a vital component of sanding and grinding. There is a direct relationship between RPM and surface speed as can be seen here:

    SFPM = (PI X DIA X RPM) / 12

    When rating motors the RPM is a determining factor how power is stated too. One formula is:

    HP = (RPM X Torque) / 5252

    So I'm not sure where you came up with "power/torque"?


    Great idea... but has flaws. My first problem is the lack of a guard or shield. All grinders, polishers, cut off tools, ect. have a scatter shield. Small rotary tools dont but I hope everyone has safety glasses when needed. Like ALWAYS. Also mounting system seems iffy at best. I would try 2 rulers, flat sides together with a bead of rubber or silicone on the flat sides and clamped light but enough to sqeeze out excess. Should give some harmonic dampening. Never use the glass disks ever, never ever! Easy way to tell is tapping the disk with a small metal rod and if its glass it will make a high pitch Tinck noise. Any others will make make more of a Thunck noise. Still not sure then dont procced. If you can get this refined and if any of my help helped you than great luck to you,Jarv


    7 years ago on Step 7

    hey, dude,,,

    u just gave me an idea to have my own buffer.

    thank u..
    keep up the good work
    GOD BLESS U,,,


    7 years ago on Step 8

    Forgive me if I missed it, but what was the point of keeping the PCB? Wouldn't it have been easier to use a multimeter to determine how much power is needed for the motor, and feed it that instead?

    2 replies

    Reply 7 years ago on Step 8

    Well to dumb it down, the HDD uses a brushless motor, which needs a special controller to drive it, which is the "PCB"


    Reply 7 years ago on Step 8

    I *just* read up on this, so correct me if I'm wrong, but from what I understand, the brushless motors need the pcb in order to switch between positive and negative, a process typically handled by the brushes, so theoretically, wouldnt it be possible to build a simple citcuit, maybe something similar to a 555 timer which would be able to carry out the same task? I understand for the sake of simplicity using the board that comes from the hdd, but i am just kind of curious about what can be done to shrink down that gigantic big board on the back of the handle, or in order to easily replace it if it were to ever break, of course, this is all of course assuming you are basic-proficient in circuitry.