Turntable made out of an old HDD

Repository

https://github.com/beetlevc/turntable

Introduction

Modern hard drives is a miracle of technology. Many of you probably have already tried disassembling old hard drives before. It's common knowledge that you can get a pair of powerful neodymium magnets out of an old hard drive, but everything else usually goes straight to trash. Today I'll show you how to make better use of your old trusty hard drive, so it could serve you longer. I'll show you how to transform a broken HDD into a turntable used in 3D scanning applications. Let's get started!

Preparing HDD

The hard drive is an ideal candidate for our task. It has an incredibly precise spindle with literally zero play, which is essential for smooth non-wobbly operation. The spindle is firmly secured in an aluminum casing, which is also a good thing. Unfortunately, HDD motor is not designed for low-speed or step-by-step operation, so we'll have to install another motor. A cheap 28BYJ-48 stepper motor will do. Every hard disk model is a bit different, so I cannot give you exact instructions here. Simply look at your HDD and find some place where you could drill holes to install stepper motor.
We will also need to transfer torque to HDD spindle somehow. The easiest way to do that is to use a 3D-printed pulley and some rubber bands. See project repository for a printable 3D model of the pulley.

The end result should look like this:

Enclosure

For this project, I made an enclosure out of 1/8" MDF and 16mm thick laminated particle board. It came out robust and heavy. On the back side, I left holes for standard 5.5mm power jack and for the controller cable. I used my CNC router to make the enclosure, but it can be cut with hand tools just as well.
See project repository for a complete CAD model of the enclosure:

Electronics

Unlike simple DC motors, stepper motors need control circuit to function. I used Arduino Pro Mini along with ULN2003 IC to drive my stepper motor, but any other 5V Arduino board (like Uno, Nano, or Mega) will do. You can use a bare ULN2003 IC or buy a premade stepper motor driver with this IC, they are widely available and dirt cheap.
I also installed buttons to control spindle rotation. The behavior of those buttons can be defined in Arduino sketch. For example, one button can be used to turn spindle a fixed angle clockwise, and the other one can be used to turn the spindle counterclockwise.

See wiring diagram:

Programming

First, install Arduino IDE if you don't have it. Then install AccelStepper and Bounce2 Arduino libraries you'll need to compile the sketch. AccelStepper library is used to control the stepper motor. Bounce2 library helps to debounce button inputs. With these two libraries installed you can now compile and upload the sketch.
The sketch itself is pretty basic, I think it is self-explanatory.

// Include the AccelStepper library found here :
// https://github.com/waspinator/AccelStepper
#include 
// Include the Bounce2 library found here :
// https://github.com/thomasfredericks/Bounce2
#include 

#define HALFSTEP 8

// Motor pin definitions
#define motorPin1  2     // IN1 on the ULN2003
#define motorPin2  3     // IN2 on the ULN2003
#define motorPin3  4     // IN3 on the ULN2003
#define motorPin4  5     // IN4 on the ULN2003
#define BUTTON_PIN_1 A0  // Step CW
#define BUTTON_PIN_2 A1  // Step CCW

// Initialize with pin sequence IN1-IN3-IN2-IN4 for using the AccelStepper with 28BYJ-48
AccelStepper stepper1(HALFSTEP, motorPin1, motorPin3, motorPin2, motorPin4);

double stepsPerDegree = 4078.0 * 2.0 / 360.0;

Bounce debouncer1 = Bounce(); 
Bounce debouncer2 = Bounce(); 

double deltaAngle = 5.0;
double currentAngle = 0.0;

void setup() {
  stepper1.setMaxSpeed(1000.0);
  stepper1.setAcceleration(100.0);
  stepper1.setSpeed(200);
  
  // Setup the first button with an internal pull-up :
  pinMode(BUTTON_PIN_1,INPUT_PULLUP);
  // After setting up the button, setup the Bounce instance :
  debouncer1.attach(BUTTON_PIN_1);
  debouncer1.interval(50); // interval in ms
  
   // Setup the second button with an internal pull-up :
  pinMode(BUTTON_PIN_2,INPUT_PULLUP);
  // After setting up the button, setup the Bounce instance :
  debouncer2.attach(BUTTON_PIN_2);
  debouncer2.interval(50); // interval in ms
}

void loop() {
  // Update the Bounce instances :
  debouncer1.update();
  debouncer2.update();

  if ( debouncer1.fell() ) {
    currentAngle -= deltaAngle;
  } 
  if ( debouncer2.fell() ) {
    currentAngle += deltaAngle;
  } 
  stepper1.moveTo(currentAngle * stepsPerDegree);

  stepper1.run();
}

To do...

There are a few things I'd like to add to this project in future

• Shutter release integration
• Additional motors to control camera position and angle
• Lasers :)

How to contribute?

Do you have a question or suggestion for this project?
Feel free to contact me on Discord or Github! Or simply leave a comment.

Resources

AccelStepper Arduino library: https://github.com/waspinator/AccelStepper
Bounce2 Arduino library: https://github.com/thomasfredericks/Bounce2
28BYJ-48 stepper motor specification and description: http://www.instructables.com/id/BYJ48-Stepper-Motor/
Arduino Pro Mini specification and description: https://store.arduino.cc/usa/arduino-pro-mini
Arduino IDE: https://www.arduino.cc/en/main/software
Arduino library installation guide: https://www.arduino.cc/en/guide/libraries