I’ve mentioned in the past that I planned to decorate the bridges of my school watch with the traditional Geneva Stripes finish and I’ve finally discovered a method that works! The Geneva Stripes finish, also known as Côtes de Genève, is a series of arc-grained bars etched lightly onto a highly polished surface, which in turn create a wave-like effect. This particular decorative finish is generally only used for the embellishment of high-grade movements and want to replicate this high grade look with my movement.
In order to create this finish, traditionally, the component to which you wish to apply the finish to is black polished and fixed to a milling table (or similar) that can be moved across two axes (X & Y for the purposes of this explanation). To begin applying the Geneva stripes, a dowel of boxwood is impregnated with a polishing paste and rotated from its center above the component. It’s then brought down, lightly, into contact with the polished surface.
While remaining fixed on its X-axis, the table on which the component is fixed is then slowly moved along on the Y-axis (from one end of the component to the other). The boxwood dowel is kept in contact with the component with consistent pressure through the entire length of each pass in order to obtain a flat finish.
Following the first pass with the boxwood dowel, the dowel is lifted and the component is then moved along its X-axis according to the desired width for each Geneva stripe. The process of moving the X-axis and Y-axis is then repeated until the entire surface of the component has been striped.
The majority of watch factories use fully automated machines to carry out this process but there are still some that utilise semi-automated machines which still require the input of a human. The two videos below demonstrate these two slightly different methods being used by Chopard and Girard Perregaux respectively.
Swiss factory methods…
There are a few of us that are interested in finishing the bridges of our movements with this finish so like on other projects we try to share the workload as much as we can to speed things up and hopefully achieve a better end result. The tutors are often supportive of our plans and in this instance our tutor was also proactive in helping us achieve the desired finish. Unfortunately the school doesn’t have either of the machines shown in the videos above so once again we would need to use our ingenuity in working with what we do have.
As with my last post on snailing, previous students at the school had attempted and succeeded to a degree in decorating bridges with Geneva Stripes. Once again though, I didn’t believe the results were of a high enough standard to be considered for use in my watch. I did initially carry out a few unsuccessful attempts on some scrap bridges using their methods a long time ago but the finish wasn’t anywhere near the standard I strive for. I discovered that the setup using the schaublin lathe was exactly what was required but the tool used for applying the stripes wasn’t up to scratch…
The setup we used is similar to the one used for snailing, by utilising the milling attachment on the Schaublin we could create a similar system to the one they use in the Swiss factories. The major difference being that it would be the tool that moves on both the X-axis and Y-axis, the bridges would remain static in the lathe at least to begin with. We would also be working vertically as opposed to horizontally which presents its own difficulties in the form of reduced visibility.
Traditionally the tool used for creating the stripes is made from boxwood but we didn’t have any at school and were unsuccessful in trying to source any so we needed an alternative. Previous students had used a pine door knob as the alternative but despite a student last year getting reasonable results I couldn’t get it to work. I then tried with a piece of steel bar but this just rubbed against the bridges and scratched them… At this point, having been unsuccessful and also in the middle of various other activities I decided to shelve my plans for a while hoping that I would discover some new information which might help.
Fortunately myself and a few of the other students frequent a number of the social media sites and from time to time we come across a number of interesting watchmakers. One of those watchmakers hails from Tokyo, Japan and his name is Hajime Asaoka. Hajime really is a special character, a product designer by trade, he taught himself watchmaking by reading the famous ‘Watchmaking’ written by the late George Daniels. Not only has he taught himself, he has created what can only be described as Japan’s first true manufacture high-end tourbillon. Hajime Asaoka Tourbillon #1 is not only a great looking watch but also an outstanding achievement for a self taught watchmaker.
Having taught himself watchmaking, Hajime’s methods are somewhat different to his Swiss counterparts in some areas and quite unusually for a watchmaker he is quite open to sharing his methods. Having flicked through some of his pictures and spotted Geneva Stripes adorning his calibre’s, I decided to ask the question- How did you achieve this finish? He responded almost instantly and provided me not only with his method but also pictures of the tools/setup. This was just what we needed because his method was far from conventional…
My tutor had mentioned previously that a high speed steel end mill might work but would more than likely produce the kind of stepped effect common in Chinese Geneva Stripes. Proper Geneva Stripes should retain a flat profile when viewed from the side, the Chinese movements don’t have this characteristic and for this reason I had avoided the end mill up to this point. However after my conversation with Hajime it turned out he was using a milling machine and end mill, the results looked fantastic!
By now we were deep into preparation for a forthcoming exam and I didn’t have the time to try it out myself but my tutor did. He spent a couple of days achieving the right setup and the results were exactly what we had hoped for, the finish being almost as good as the Swiss factory finish. Unfortunately I neglected to take any pictures of this first attempt so you will have to take my word for it and check out the pictures of our own first attempt.
Having seen the results that our tutor had achieved we decided to give it a try ourselves as soon as we had the chance. I definitely wanted to stick with the standard formation of Stripes but my fellow student, Abraham Altairy, decided he wanted something a little different. He wanted to try circular Geneva Stripes similar to those used on vintage Hamilton pocket watches so we set to work. The only difference to this setup is that we would use the dividing head on the lathe to rotate the bridges and the end mill would remain static except for when moving to start the next circular stripe.
And in action…
Now you have seen the setup and it in action, its time for you to see the results of our first attempt. We were really pleased with how well it turned out and although I’m not as keen on the circular style, the quality of the finish is amazing. We haven’t had a chance to experiment any more since so this is the setup we will carry forward. Time is now running out to get our watches finished before we leave school for good in July so as soon as our bridges our completed, the stripes will go on and off they will go to the platers. Thanks again for reading and I must say a big thank you to Hajime for sharing his expertise.