I knew the first project for Barrelhand Timepieces had to be something special. I didn't want to make another generic micro brand with a slightly different case and dial that has been done a thousand times over and floods the 'watchmaking" market. If I was to create a timepiece it had to bring something new to the table, both in mechanics and design. After months of designing different mechanisms i had finally settled on the overall complications. I began developing a new method of displaying minutes linearly. linear minutes have been done in the past on other haute horlogerie brands such as HYT's H3,however the mechanism to actuate it was to be entirely different.
my inspiration came from a vinyl record and how the needle follows a groove as it slowly makes its way towards the center of the vinyl. using this design i calculated the curvature of a cam path(highlighted orange) which could glide a pin up and down to linearly display minutes. This cam path rotates around the central axis, creating a beautiful dance of motion which will span the whole dial of the timepiece.
The next mechanism I wanted to implement was a Jump Hour. not only does it make time reading easier but there is something exciting about watching the hour switch over from one to the next. One of the set backs to traditional jump hours is that they are comprised of many components and the time can not be set backwards. while studying intermittent motion for an engineering exam I was reminded of the Geneva gear. This was not the first time I had seen this mechanism as it has been used in watchmaking for centuries, mainly for date complications or wandering hours. By implementing this mechanism I minimized the amount of components needed while allowing the time to be set both forward and backward.
The formulas needed for designing Geneva gears are fairly simple, however it becomes much more difficult the smaller it is scaled and as you increase the number of points the gear needs. Most Geneva gears have 4-5 points however in my case I needed 12, 1 for each hour. The issue with this is that as you add more points, your gear gets more and more intricate and the walls become much thinner. On top of this the diameter of the gear had to be no greater than 16mm given previous design constraints. Now I could see that my simplification of the jump hour was in fact going to be more complicated than I had originally imagined.
After developing the housing and main plates for these mechanisms I created a basic case that would hold it all together. The first prototypes are never a thing of beauty as you can see below, but that would get improved later on. At this point, the main focus was to get a mechanical proof of concept. The parts were printed using a UV cured stereolithography printer which has a print resolution of .01mm (about 1/10th the thickness of a human hair). This 3D printer will serve as the basis for all further prototype iterations due to its low cost and extreme precision, even for tiny gears like the one above. Once printed it was time for assembly and sure enough none of the mechanisms functioned properly. The drawback to 3D printers is that there is no way to tolerance the fitments so you must take that into consideration when designing. Nonetheless you learn a lot from initial prototypes, take as many notes as you can and improve on them for the next prototype iteration.