Tick. Tock.

You know I got a watch last week.Like most things I do I tend to throw myself headlong into something and learn as much as I possibly can about almost everything.Watches, it turns out, is no exception.First, listen to this ticking: Post-processed WatchThat is what my watch sounds like in real time. Of course this is quite a bit amplified and post-processed so you can hear it. It sounds a lot like the into to 60-Minutes. Everyone has heard this type of sound. In my watch's chase it has 28,800 vibrations/hour -- or 8 ticks/second. Listening to the sound can tell you that much.Now, let's slow it down a bit: 10-times slower ticking. This is the same sound as before, just 10x slower. When you listen to it, see if you can hear each tick break down into 3 individual sounds. Here's a couple of cycles visually so you can see what you're trying to hear.In the above example the first pulse has three distinct peaks and the second has four. Let's look deeper into this.First we must consider the escapement. My watch, like almost all modern mechanical watches, runs with a normal lever escapement. Basically what's happening is the balance wheel spins back and forth eight times a second -- a total of four round trips. Each time it does three things.

  1. The impulse pin on the balance wheel hits the pallet fork. In the above picture it's the red dot near the center of the balance wheel. This makes the first click.
  2. In the above case the wheel is turning counter-clockwise. This will move the pallet fork (the thing with the two red jewels on it) unlocking the escape wheel (the bottom wheel). It does more than that though. The escape wheel is driven (indirectly) by the main-spring so it's under tension and wants to turn clockwise. Additionally, the pallet jewel is sloped on the side. As the pallet fork unlocks the escape wheel, it pushes on the fork. This in-turn gives a nudge to the balance wheel through the impulse pin. This is the second click.
  3. As the pallet fork swings over it will lock the escape wheel on the other side. The extent of this swing is set by the pins on either side. The speed of this action is governed by the speed of the balance wheel -- the faster the balance wheel spins in the middle of it's oscillation, the bigger the amplitude of its swing. This is the third click.
  4. In my watch the second-hand advances once every full cycle; the rest of the works move every other vibration. That's the forth click on the right. (It's hard, if not impossible, to hear this pulse)

You can tell a lot about a watch based on just listening to it. You can tell if it's running fast or slow. You can tell any differences between the tick and tock. You can tell if the watch needs lubrication (if the amplitude is lower than expected). You can tell any lack isochronism based on difference in wind. All sorts of stuff.Here's a pro-level machine that measures this -- the instructions go into all the theory deeper than I'm getting into. The Witchi Chronoscope X1 (G2) does all this and more.I'm thinking about making something on the cheap that does the same thing.  :-) 

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