Final Design Report: https://drive.google.com/file/d/12HgZX-9Dut5Lg7B7ktfkFnhn3Aa0GKKF/view?usp=sharing

Background

For the course Machine Design, taken while studying abroad at Lund University in Sweden, I was tasked with pursuing a project of my choice. Due to my recent passion of watchmaking, I took on the challenge to design and create my own watch. The project focused on developing a unibody watch, integrating the dial and case into a single unit. Watchmaking has evolved significantly since the 16th century, with advancements in materials, mechanical movements, and aesthetic design. This project aimed to leverage modern manufacturing technologies to create a unique and efficient watch design. The project was divided into three main phases: research, design, and manufacturing/assembly.

Problem

The main challenge was to accurately predict the winners of each match in the March Madness tournament and estimate the probabilities of teams progressing through each stage. Given the nature of the tournament, which is prone to upsets and "Cinderella stories" where lower-seeded teams unexpectedly advance, creating a reliable predictive model was complex.

Solution

Research:

The initial phase of the project focused on determining the most suitable movement for the watch. There were two primary options: automatic movements and quartz movements. Automatic movements use a mechanical system driven by a rotor that winds the mainspring through daily wear, resulting in a smooth sweeping motion of the hands. Quartz movements, powered by a small battery, provide a more robotic motion but are generally cheaper and last longer. To distinguish the watch and maintain a traditional feel, the decision was made to use an automatic movement.

The research compared two main brands of automatic movements: ETA and Miyota. The Swiss-made ETA movements are used by high-end watchmakers like Breitling and Omega, while Miyota movements are employed by brands like Bulova and Timex. The ETA 2824-2 movement was chosen for its reliability and availability at a reasonable price. Detailed engineering drawings and specifications of the ETA 2824-2 were studied to understand its integration into the unibody watch case, focusing on the unique geometry required for the dial and case assembly.

Design Process:

The design phase began with establishing a fundamental layout that included essential features for the watch:

Dial Feet: Two cylindrical feet on the back of the dial face, positioned to secure the movement.
Movement Clamps: Slots within the case to fit the clamps that secure the movement.
Glass Crystal: A raised seat on the dial face with a press-fit diameter for the crystal.
Movement Stem: A central hole for the stem, ensuring it is thin enough for the hands to be assembled above it.
Date Window: An opening in the dial face to display the date.
Stem and Crown: A hole on the side of the case for the stem and crown to allow time and date adjustments.
Caseback: A method for attaching the caseback, either by screws or adhesive.
Watch Straps: A 20mm space to fit standard watch straps with holes for spring bars.

Measurements from engineering drawings and online resources were used to ensure precision. For features where measurements were not available, tools like micrometers and calipers were used once parts arrived. The design also included aesthetic elements made possible through additive manufacturing:

Hour Markers: 12 bridges connecting the dial face to the case, creating a 3D effect.
Dial Face Pattern: Expanding circles inspired by luxury watches like the Rolex 1908, adding a captivating design.
Fluted Bezel: Similar to Tudor Style, providing a cohesive look with the round bridges and circular dial design.

Manufacturing and Assembly:

Manufacturing:

To ensure manufacturability, collaboration with Satabdee Dash, an expert in additive manufacturing, was crucial. Adjustments were made to the design to guarantee successful printing. The design aimed for a metallic-looking material to enhance the watch's appeal. Initial prototypes were printed using FDM-based Prusa MK4 3D printers, with a 0.25mm nozzle for tight tolerances and high resolution. These prototypes helped verify the fit of the movement and the accuracy of all features.

Final prototypes were created using a Form 3 SLA resin-based printer, providing higher resolution and better assembly verification. The ultimate print was done using a Bambu X1C Printer with a metallic-texture bronze filament, offering a balance between appearance and functionality.

Assembly:

The assembly process started by securing the movement to the printed case with movement clamps. The stem and crown were attached through the case to ensure functionality, and the time was set to midnight. The next step, attaching the hands, was the most challenging. Using a hand pushing tool, the hour, minute, and second hands were carefully placed in the 12 o'clock position and tested for interference with the dial face. Finally, the glass crystal was attached using light plastic adhesive, and the caseback was secured. The watch straps were attached using 20mm spring bars, completing the assembly.

Conclusion:

Throughout the process, several iterations and test prints helped refine the design and assembly techniques, ensuring a functional and aesthetically pleasing final product.

By combining traditional watchmaking elements with modern additive manufacturing, the project achieved a unique, integrated unibody watch design that was both efficient to produce and visually appealing.

Watch Design - Project "Nexus"