Have you ever thought of making good use of old mechanical hard disk lying around in your collection of junk as most of the tech enthusiasts do have in some corner of their house? I had one Samsung 7500 RPM HDD lying around with me which I thought to put it at some good use. First off I started with removing all the screws form it and taking it apart. Note that one screw is hidden below that branding and specification sticker labeled on the hard disk. So if you are finding it difficult and something getting stuck and things are not getting apart then look for a screw beneath the sticker.
While taking everything apart think of salvaging all the screws and neodymium magnets as that may come handy in some of your projects and hard drive neodymium magnets are most powerful magnets that you can get free of cost.
Once you rip apart everything solder three wires may be of same color or different does not matter much to a brushless motor that is found inside of the hard drive. Now we need to elevate the height of the motor as we cannot have a working area so low. So we will use the RC standoffs aluminum to raise the motor height to 30mm. After fixing the motor on to the hard drive base with standoff we get plenty of room to fix the large diameter sanding paper disk.
We will now wire up a hard drive/Brushless motor tester board to our sander setup. Then wire that correctly in a delta or star it can accept both types of brushless DC motors and you never know what motor you will discover once you open up the hard drive. But that's not going to be a problem as this driver board supports both types of configurations.
Once everything is wired up fix the entire assembly on any thick minimum 10 to 12 mm MDF board just with hot glue but use it in plenty as it should be glued rock solid. You can also use an epoxy adhesive. Also, use some soft silicone feet to remove vibrations of the assembly so as to stop it from running across the place due to high RPM and bit offset of sanding disk creating vibrations. Mount the hard disk and over it mount the sanding disk and fix the locking ring with five six or seven or sometimes 8 screws. put a switch and a 12 v barrel jack connector. wire it and glue it as a supply to the motor drive controller taking care of the polarity.
Now the fun time starts. Grab any 12v 2Amps supply adapter as this hard disk motor does not require anything above that and you are ready to rock and roll.
There are tonnes of uses as this is a very small setup and handy. You can use this sharpening pencils, sharpening your knives, making knives out of hacksaw blades and even from HSS hacksaw blades. I used 180 grit sanding paper disk. You can use any similar according to your usage. In the video, I have shown some of the uses and had a lot of fun playing around with it.
I hope you loved having to read this instructable thank you for your valuable time reading.