WatchTech

I thought about listening when David Walter posted here about his MicroSet device "hearing" a recent earthquake. It (the tester) was actually "listening" to the escapement in his pendulum clock, and it "heard" variations in the escapement's action when the ground shook.

If you never knew how watches are regulated or diagnosed, then Please Listen Up! 

Watchmakers adjust escapements by listening to their timekeeper's tic and tac (in French) or tick and tock (in English). 

You may have seen a device like this on a watchmaker's bench; this photo came from Grand Seiko's Morioka Studio. The four Witschi Watch Expert machines are connected to microphones that are listening to the Grand Seiko movements in front of our inspector. The results are displayed on the screens.

In prior generations, watchmakers used electro-mechanical devices like this vibrograf to listen to a movement and then display the results on a thermal paper tape.



In-between these machines, we have had some PC-based analyzers, such as this eTimer software package which I formerly used.

But what exactly are these devices listening to?????

Don and I asked Witschi if we could share with you some of their training material to explain how the tic tac is translated into graphical form. They were happy to oblige and to help me explain how to use a watch timer, for beginners.

The watchmaker first has to set his listening device to hear the proper frequency which is designed into the watch (18,000, 28,800, 36,000, etc.) Most machines will do this for you, but older ones like my vibrograf must be set by the watchmaker. Then you set the amplification (or listening) volume properly, and begin your analysis.

Our testing machine (screen or paper) takes the measured interval between some of the sounds it is hearing, and compares that to its own precisely calibrated reference timer. 

NOTE: Needless to say, since this is an acoustic test, you cannot perform it accurately if you are playing loud music in your atelier, or tapping your fingers on the table near the tester!

The testing machine compares its own timer to two successive watch beats. If the measured time on the watch is exactly the same as the internal timer, a new dot is placed adjacent to the first one. If the new beat is a bit too early (fast) or too late (slow) the dot is shifted up or down relative to the first one. Thus the row of dots on the display (or paper) forms a line that indicates the rate deviation of your movement. On the Witschi screen a perfect line is horizontal. On the vibragraf and my PC, the line should be vertical. A sloping line shows the watch needs a bit of attention; a jagged line or two lines means something else we will discuss soon.

FIRST NOISE A

THIRD NOISE C

SUMMARY

OK, so what do we do with these noises? You may recognize the waveform shown above in black and green is also shown in the photo of my eTimer screen. Any timing machine analyzes that waveform. 

Remember we want to see a nice, straight dotted line on the screen or the paper. 

If there are two lines, that means the watch is out of beat which generally means that the impulse pin is not centered in the fork when the balance is at rest (or balance wheel is swinging too far in one direction, and too little in the other). If the line slopes slightly,  it's ok. If it slopes too much it's either slow or fast and must be regulated.

So one straight line, no slope is perfect. Sloping a lot, or two lines are problems. What if the line(s) not straight across (or down) the screen or paper tape? We can see that too with our analyzer.

As we work our way through the illustrations you can see how listening carefully can then produce a diagram which helps the watchmaker diagnose the watch. Sometimes it means you need new parts; aternatively you might need to clean and reassemble the escapement or the entire timepiece.




Here are a few more patterns from the Witschi training manual.

That's all I have for today. Of course there are exceptions for co-axial escapements, new silicon designs, ultra-high frequency movements, etc. Witschi provides special settings for those watches.

I thank you for your attention, and thanks to Witschi for permission to refer to their technical manual, which you can find here: LINK TO MANUAL.

Cheers,

Cazalea

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