One of the things I really like about working on watches is discovering the hundreds of ways different companies have used to accomplish exactly the same end result. I mean for the most part these are little machines that tell time, yet there are thousands of different watch calibers which have been produced over the years. During the 60s, I think we saw a lot of innovation simply because there were so many companies and patents in place that you had to come up with a different way to do it sometimes.
Most of the times the solution is very elegant. My favorite example of this is a moon phase indicator. The length of a lunar month is 29.530589 days. This happens to be almost nearly 59/2. The simplest solution therefore is to make a gear with 59 teeth, paint two moons on it and advance it once a day. This configuration allows for an error of 1 day every 33 months, or an error of less than 2 days during your typical service interval. Most people won’t even notice that kind of an error.
An example of a not-so-elegant solution is the ETA 2895. This movement is the slim automatic 2892 modified to have a seconds hand at 6 o’clock instead of a sweep hand. Now, keep in mind that it is simple enough to design a movement that has a sub-second hand as opposed to a sweep second hand. There are hundreds of them on the market, including nearly every pocket watch. Why? because it is almost the natural configuration of a watch movement. A sweep second requires a stacked train or a driving wheel. In the 2895 ETA takes a movement which has been configured for a sweep second hand (with the 4th wheel at the center of the movement) and converts it back to a sub-second hand. To do this they make a long post on the escape wheel, which extends through the mainplate and is supported by an additional bridge on the dial side. To that post they have added a secondary pinion which drives a wheel on the dial side. This wheel is in the wrong place though, so they put an intermediary wheel and then a third wheel on the dial side with a post for the seconds hand. This solution is really not elegant at all. What they should have done is designed a new caliber with the fourth wheel positioned at 6 o’clock, or maybe just resurrected one of the thousands of out of production calibers that already have a sub-seconds hand.
Anyway, I don’t know that there are any real problems with the 2895, but it is definitely the least elegant solution to the problem of a sub-seconds hand. I suppose an Engineer made this decision because it only required manufacturing 6 or 7 extra parts instead of a whole new watch.
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One Comment
I’ve worked on at least a dozen of these. It does work – however I am never a proponent of using magnets, such as the ones found under the sub-seconds wheel – inside of a mechanical watch. It also seemed like a bad idea to draw power from an area as sensitive as the escape wheel – I have noticed these movements do not consistently perform as well as a standard 2892 and I think this design has something to do with it.
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