Mastering Hard Drive Disassembly – Extracting Key Parts for a DIY Rotary Tool

In Part 1, we explored how the motor inside a hard drive holds the potential to become a powerful rotary tool. Now, it’s time to take action. In this part, we’ll walk through how to disassemble a hard drive step by step and extract the essential components for building your DIY grinder. This isn’t just dismantling—it’s precise harvesting of valuable parts.

A photo showing a disassembled hard drive laid out on a wooden surface, with labeled parts including the platter, spindle motor, actuator arm, PCB, and neodymium magnet, prepared for DIY rotary tool conversion.


Most discarded hard drives, whether IDE (PATA) or SATA, contain platters, arms, controller boards, strong neodymium magnets, and of course, a BLDC spindle motor. To convert it into a rotary tool, you’ll mainly need the motor, rotating shaft, and the structure for attaching the tool head.

 

 

1. Tools You’ll Need

  • Torx screwdriver set – Common sizes: T6, T8, T10
  • Thin flathead screwdriver or prying tool – To lift the casing
  • Tweezers or utility knife – For cable removal
  • Wire cutter or pliers – To cut or remove fasteners

Most HDDs use star-shaped Torx screws. If you try forcing it with the wrong tool, you may strip the screw. A flathead screwdriver might work in some cases, but use it only as a last resort. Precision matters if you want to reuse the parts without damage.

2. Step-by-Step Disassembly

Even after removing all visible screws, the top plate may still seem sealed. Insert a thin flathead screwdriver in the seam and gently twist. Once opened, you’ll see the following internal structure:

  • Platter – A polished metal or glass disc
  • Actuator Arm + Read/Write Head – For reading data from the platter
  • Neodymium Magnet – Powers the movement of the arm
  • Spindle Motor – The 3-phase BLDC motor that spins the platter

What we want for our rotary tool is the spindle motor and the platter (or mounting area). You can remove the rest or repurpose it later.

 

 

3. Pro Tips for Extracting Key Parts

① Removing the Platter: It’s usually secured by a central screw or rivet. Once removed, you can extract the platter and later use it to mount sandpaper or cutting discs.

② Identifying the Motor Terminals: Remove the controller PCB on the underside to access the motor terminals. Typically, you’ll see 3 terminals for A-B-C phases and a possible 4th for center tap (not needed for ESCs). Use a multimeter to measure resistance and determine the correct wiring.

③ Extracting the Magnet: Be very cautious—the neodymium magnet is extremely strong and can pinch your fingers. After removal, it can be reused for other DIY applications, tools, or fridge magnets.

 

 

4. What You Actually Need for the Grinder

  • Spindle Motor – The core of the rotary tool
  • Platter or Shaft – Used to mount sanding or cutting heads
  • Motor Terminals – For ESC connection (3-phase output)
  • Lower casing – Can be reused as a mounting base

The actuator arm and head can be removed. Unless you want to create an art project, they won’t be needed for this build. You can discard the PCB unless you plan to repurpose it for electronic components.

 

 

Conclusion: Disassembly Is Where the Real Build Begins

Taking apart a hard drive is the first step in building your rotary tool—and it’s also one of the most exciting. There’s something deeply satisfying about seeing the internal precision of these devices, and even more so when you realize you can turn it into a powerful, useful machine.

In the next part, we’ll connect the extracted BLDC motor to an ESC, apply power, and get it spinning for the first time. Grace’s DIY grinder is about to come to life.

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