Take me to the Steps

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I bought my first 3D printer in 2013 and immediately started creating custom Lego gears for my kids. Next, I challenged myself to design a gear with a Swiss lever escapement — the mechanical linkage in a timepiece that swings back and forth and creates the “ticking” sound. This sparked my passion for 3D-printed clock design, and my first 3DP wall clock was ticking 6 months later.

Then I got an Ultimaker 2 and a new challenge. I was obsessed with Vianney Halter’s Deep Space Tourbillon, a Star Trek-inspired wristwatch whose mechanics rotate visibly at its center. In watchmaking, the tourbillon is a slowly spinning cage for the watch’s escapement and balance wheel, which is meant to average out the effects of gravity on the timepiece’s accuracy. With advancements in modern watchmaking a tourbillon is unnecessary, but designers still include it as a demonstration of their skills. It’s a piece to really show off, and it takes 100% focus to achieve.

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With this in mind, I knew my 3D-printable watch needed to have a tourbillon. Like the Deep Space Tourbillon, the ticking-unit should be in the center of the watch, and the hands should rotate around it, using big internal gears. The result is a reinvention of a classical tourbillon, adapted to 3D printing.

This windable watch consists of 51 printed parts, 15 pins, 14 washers, and 21 screws. When it’s all screwed and snapped together, it’s clock-sized: 4″ (102mm) in diameter. I’ve shared the 3D files on Thingiverse so that anyone can make their own.

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Designing a Tourbillon

My first experiments in printing a tourbillon involved the creation of small-module 3D-printed gears. For gears, a module is a unit that indicates the distance between gear teeth. It’s the ratio of the reference diameter of the gear divided by the number of teeth. It turned out that my Ultimaker could print working gears with module 0.5 — half the size of my Lego gears. I decided to design the gears with module 0.7 to be on the safe side.

Next, I needed to design a printable escapement small enough to fit inside the tourbillon cage. By arranging the balance wheel and the escapement gear in a concentric, coaxial orientation, I minimized the build volume. For driving the escapement, a smaller gear was added to the design.

The transmission in the tourbillon is similar to a planetary gear with a stationary annular gear, and the tourbillon cage as carrier. Designing this in Autodesk Fusion 360 was surprisingly easy, and didn’t require much prototyping. The tourbillon turns at 1 revolution per minute — so the second hand is attached directly to it.

The design of the minutes and hours gears and hands was straightforward. I started with the design of the clock face, and arranged the gears behind the tourbillon. The gear ratio is simple mathematics.

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A bigger challenge was the design of the mainspring. I designed and 3D printed a couple of spiral-shaped objects, and tortured them until they broke. I also learned (from Google) that a relaxed mainspring must have a special shape in order to keep the driving force constant. From my experiments, I learned that PLA wasn’t suitable — it deforms relatively quickly, and the driving force diminishes over time as the spring wears out. The behavior with PETG filament is still not the best, but compared with PLA it’s much better. In the future I’d like to experiment with other materials. The final 3D-printable mainspring has an unwound length of about 2 meters, and takes a long time to print.

I started printing my first tourbillon watch in June 2015, and the final watch was working by December. When I decided to publish the tourbillon design on Thingiverse and YouTube, I never expected such a response. Now I’m receiving offers to work on other 3D-printable designs. I’m hoping to start a new career, while continuing my passion for watch design as a side project.

Build YOUR OWN tourbillon clock

Building this project requires patience and quality control. You’re building a watch mechanism much larger than professional watchmakers have to fuss with, but still, developing your eye for print quality, weight, and material strength is key to the project’s success and the accuracy of your timepiece.

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Project Steps

Print all the Pieces

Everything inside the tourbillon cage — i.e. the hairspring, balance wheel and pin, anchor (lever), escapement wheel, and planet gear — was printed in PLA at high resolution (0.06mm layer, 0.8mm shell). All other parts were printed at normal resolution (0.1mm layer, 0.8mm shell). All parts can be printed without support, except the pawl key (not shown here). I got best results using my Ultimaker 2 with a 0.4mm nozzle.

The infill of the anchor is 80% in order to create a more balanced center of gravity. The rest of the pieces have 30% infill.

For the case I used PETG (slightly bendable, shock absorbing). All gears are printed with PLA (harder and less friction). In these photos, black and yellow parts are PETG, orange and red are PLA.

The mainspring is printed in PETG (PLA would probably break after a while). I switched off the “combing” setting in Cura. While this is a cool feature for ordinary parts, it causes problems with large spiral-shaped parts, as the print head does many useless traveling moves. The nozzle oozes during these moves, and when it resumes printing it can be empty of material; the resulting under-extrusion can be disastrous.

The hairspring needs to be printed in PLA. Other materials can work, but you’ll find that the watch runs too slow, or too fast. Because of this, any material substitution requires a new spring design.

Small holes usually don’t print very accurately, so use a drill to smooth the inner surface — the balance wheel especially needs to rotate with very little friction and very little play. If you don’t find pins or screws with the recommended diameter, you can use slightly larger fasteners — there’s some room to drill the holes out.

For best adhesion, print on a heated glass bed cleaned with a mix of alcohol and water. To remove parts, pour a few drops between the part and the glass. The effect is miraculous — the parts can be removed immediately without applying any force.

Besides the winding key there’s also a pawl key to unlock the ratchet pawls so that you can fully unwind and relax the mainspring when your watch is not in use. This certainly will extend its lifetime.

You can even print a chain for pulling it out of your pocket. OK, it needs a big pocket!

Build the Clock

Then build the 2 main modules — the tourbillon and the mainspring “going barrel” — and assemble the clock gearing.