Building Your Own Custom Watch From Scratch

This project covers how to build a 3D-printable (or CNC-milled) custom watch from scratch.

A common limitation of many DIY projects is that they often fall short compared to commercial products. For this project, I focused heavily on ensuring the final result wouldn't lag behind retail standards in terms of both design aesthetics (depending on your taste, of course) and functionality, such as water resistance and UX.

Here are the key design features I’d like to highlight:

1. Use of a Bayonet Connector: Instead of traditional press-fits or screws, I used a simple yet highly reliable bayonet connector to connect the watch case and case back. This ensures a robust assembly, allowing various materials and manufacturing methods.
2. Simplicity: My goal was a redundancy-free internal design, achieved by integrating the spacer and the dial into a single piece. Also, the unconventional, rebellious crown placement just brings me joy—it's a purely personal preference! :]
3. A Platform-Based Structure: The simple connection joints and modular components allow for endless variations. You can easily modify the design and build your own custom watches with different movements or distinct outer looks.

1. Watch movement : Miyota 8N24 movement
2. Crystal : diameter 39mm, thickness 1.5mm
3. watch hands & crown
4. gasket : teflon gasket (dia: 39mm, h: 1.25mm, thk: 0.4mm), O-ring(dia: 43mm, thk: 1.25mm - 1mm would be easier to assemble)
5. watch strap (width 22mm)
6. 3D printed & CNC machined(optional) parts

The watch was designed using Autodesk Fusion 360.

For the movement, I used the official engineering drawings typically provided by the manufacturer as a reference, and designed the dimensions of all the other components around it.

Getting the tolerance right for the watch crystal was one of the most critical parts of this project. I used a 0.4mm thick Teflon gasket, and through testing, I found that a 0.375mm tolerance was required to achieve a secure and reliable fit during assembly.

To find the appropriate tolerance between components, I went through several rounds of prototyping. If you plan to modify the dimensions, I highly recommend keeping a multi-stage manufacturing process in mind.

After confirming the fit, I had the body CNC-machined out of aluminum.

Press-fit the movement into the spacer, then install the watch hands in the correct order.

While there are specialized tools specifically for setting watch hands, if you want to take the budget-friendly route (like I did), a pair of tweezers and your fingernails are more than enough. Just make sure to double-check that all the hands are appropriately leveled and parallel before the final assembly.

Insert a gasket into each socket, then press-fit the crystal into place.

Using any flat, rigid object to apply pressure is sufficient.

(I had to do some additional carving because I accidentally used an incorrect design revision for one of the parts before sending it for CNC fabrication.)

The stem that connects the movement to the crown must be cut to the correct length. A pair of side cutters is sufficient for this task. However, be sure to clean up the threads that become deformed during cutting.

The stem can be released by pressing the small button located on the back of the movement.

Install the gasket onto the front side of the enclosure, then assemble it with the green cover. Use the included 3D-printed tool for this step.

Insert the spacer and reinstall the stem.

Attach the case back with its gasket in place. Again, use the 3D-printed tool provided in the design to complete the assembly.

Install the watch strap of your choice.

...and you're done!

Design is available on this link.

Any modification is possible with this file. Feel free to remix, tweak, and adapt the design for personal projects—except for commercial use—provided that you give appropriate credit to the original creator.

If you want to see my (quasi-)real-time ongoing projects, Follow me on Instagram: @automaton_42

Good Luck :]