Watch Winder

This is the Watch-Winder using the Nema 17 and 60x60x15 mm 12V fan. control by esp32 and A4988 or TMC2209.

The link on YouTube for wire is: How to control Nema17 stepper motor with Esp32 (this is compatible with A4988 and TMC2209 for less noise)

The code for esp32 (2rpm for more than 2 weeks running consecutive): watch-winder/src/main.cpp at master · QuangVuong501/watch-winder

The code for esp32 (5rpm for overnight (about 8 hours)): watch-winder-5rpm/src/main.cpp at master · QuangVuong501/watch-winder-5rpm

You can buy the nema17 here: Amazon.com: STEPPERONLINE 1 Pack Nema 17 Stepper Motor Bipolar 1.5A 42Ncm 42x42x38mm 1.8deg 4 Wires with 1m Cable and Connector : Industrial & Scientific

12v 6015 Fan: Amazon.com: ANVISION 60mm x 15mm DC 12V Brushless Cooling Fan, Dual Ball Bearing : Electronics

Notes: if you need help just contact via email: [email protected]

NO-SCREW REQUIRED

The code is only compatible with the TMC2208, TMC2209

Design and Optimization of a Gravity-Driven Kinetic Energy Storage System for Automatic Timepieces using Micro-Stepping Electromagnetic Actuators.

1. Classical Mechanics: Force Resolution and Gravity (30-Degree Inclined Plane)

At the heart of an automatic watch is the rotor (oscillating weight), which relies on gravity to rotate and wind the mainspring. By mounting the watch at a 30-degree angle (relative to the vertical plane), you have engineered a perfect balance of forces.

• Gravitational Force (P): P = m * g
• (Where "m" is the mass of the rotor and "g" is the gravitational acceleration of 9.81 m/s^2)
• Tangential Force (Pt): This is the force component that actually drives the rotor to spin.
• Pt = P * sin(alpha)
• At alpha = 30 degrees, Pt = 0.5 * P. This component is strong enough to easily overcome the static friction of the watch's winding gear train, allowing for smooth, efficient energy transfer.
• Normal Force (Pn): This is the force pressing directly against the rotor's axle.
• Pn = P * cos(alpha)
• Keeping the angle at 30 degrees instead of 90 degrees (vertical) significantly reduces Pn, minimizing axial wear and tear on the delicate rotor pivot over years of continuous use.

2. Electromagnetism: Stepper Motor Dynamics & Vector Control

Instead of using a cheap DC motor, your project utilizes a hybrid stepper motor (Nema 17) controlled by a state-of-the-art TMC2209 driver. This is a masterclass in applied electromagnetism:

• Electromagnetic Induction: The ESP32 sends precise step pulses to the driver, which sequentially energizes the stator's copper coils. This generates a rotating magnetic field that interacts with the permanent magnet rotor, creating a precise holding torque.
• StealthChop2 Technology (Vector Control): Traditional drivers like the A4988 use harsh square-wave current chopping, causing magneto strictive noise (that high-pitched squeal). The TMC2209 uses advanced algorithms to feed the coils with smooth sine-wave currents, translating into virtually silent, vibration-free rotation at ultra-low speeds (2 RPM).

3. Thermodynamics: Joule's Law & Forced Convection

Even at low speeds, electrical energy is partially converted into heat within the motor’s internal coils due to winding resistance.

• Joule's Law of Heating: Q = I^2 * R * t
• (Where "I" is the current, "R" is the coil resistance, and "t" is the operating time)
• Forced Convection: By incorporating a cooling fan, you introduce a mechanical fluid flow (air) over the heated surfaces. This dramatically increases the heat transfer coefficient, ensuring the system maintains a safe operating temperature.
• Material Science Connection: Keeping the system cool prevents the 3D-printed structure (PLA) from reaching its glass transition temperature (Tg ≈ 60°C), preserving the structural integrity and dimensional tolerance of your design.