AHCI

Elma or Witschi?
Apr 03 2008,13:40 PM

Hello,
I love watches. Though I understand this may seem an obvious statement here, that's my point. I love watches so much that I prefer to make them tick properly rather than owning them. So I become a hobbyist watchmaker and now I'm looking for a timing machine. After some months spent in my search I've found very few candidates:

• Witschi Watch-Expert (II or III)
• Elma Watch-Matic (II or III), this one seems a "clone" of the Witschi, maybe just rebranded?

And I've currently taken out of the list:

• Vibrograf B-500 (http://www.vibrograf.com/Pages/Mathorloge/horloge_010.htm) because it's too big to fit the small room I've reserved for watchmaking activities. Even a second-handed B-200 would be too big.
• MicroSet Watch Timers (http://www.bmumford.com) because I simply don't like them. I love to love my tools, my heart just doesn't tick for this one.
• TYMC MTG-3000 for the same reason above (despite the fact that this tool is offered at a very appealing price). There seems to be many similar (if not identical) MTG-3000. There's a model in the A&F Switzerland catalog (http://www.afswitzerland.com), there are many internet sellers offering chinese "WeiShi" timing machines (all of them looking like the TYMC) and there's the TYMC web site itself (http://www.timegrapher.com/tymc/mtg_3000.html).

There's very little information around about how to use them (e.g. how to set the lift angle for an old movement), so opinions, suggestions and experiences in using time machines in general are very welcome.

Best regards,

// slurrp

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the Elma and the Witschi are the same as far as I can tell
Apr 04 2008,03:00 AM

I compiled a huge list of nominal lift angles for older movements a few years back I'd be happy to send to you, but I'd really recommend spending some time training yourself to visually observe the amplitude where it corresponds with whole (and/or half) intervals of the angle between the spokes and setting the lift angle on the machine so that the reported amplitude matches your observations.  This is the most accurate way to check amplitude with these machines and you don't need to know the lift angle reported by the manufacturer (which is always an average or baseline anyway).

_john

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thanks john,
Apr 04 2008,10:33 AM

Receiving your list of lift angles would be immensely appreciated.
I've just sent you a private message
// slurrp

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Results From Each Brands...
Apr 04 2008,11:45 AM

Hi Slurrp & -John

Thanks for the comprehensive list of timing machine. An interesting topic and have several questions.

1. Regardless of the brands ( made & prices) , do they produce very close results?

2. Which machine is the benchmark for the watch industry ( be it Swiss or German)?

3. Is there a certain standard which all these timing machine calibrate to?

Kong


 

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Results, more or less...
Apr 04 2008,16:21 PM

Hi Kong,

Do they produce very close results? In the short term, likely yes.
But robustness, reliability and stability over time and environmental conditions could make the difference in a few years (ageing) or even in minutes (temperature changes).
The basic measurements every timing machine evaluates are rate (in seconds per day) and beat error (in milliseconds, it should be noted that at 28,800 bpm one tick is 125ms so a pretty high beat error of 1ms equals a mere 0.8%). Most of them will also show those parameters in a graphic form over time (making you possibly find defects in the power train, like an oval gear or a broken ruby), let you hear the sound of the movement on a loudspeaker, show the balance amplitude for a given lift angle. Some of them will also automatically detect the proper beat rate.

A timing machine is essentially a recorder of very weak mechanical noises. So you need a high-sensitivity, low-noise transducer (i.e. microphone) to detect and convert them into electric signals. Then you must take into account that these "noises" are (or at least they should be) periodic. You then need a time base to compare them to. Signal processing algorithms are required to reduce residual noise, correlate many periods each other to eliminate spurious signals (averaging), and finally calculate and show the results on screen or paper.
Other features are more or less important depending on what are you going to use the tool for. A PC interface or printer output, automated measurement capabilities, a bigger display, a smaller footprint on your bench might sound paramount to some, useless to others.

Of all those things, time base and transducer, in this order, are the most important ones. Signal processing is no longer an issue with today's digital processors as long as the transducer is just decent. Time base precision (and its stability over time and temperature) is usually the discriminating factor between timing machines. As of today, a state-of-the-art time base – usually a thermo-compensated quartz – is able to detect up to 0.1 ms beat error and will keep its precision and accuracy for years. If you'd want to make a quartz watch using such a time base, then you'll have a fantastic figure of 1 to 5 seconds per year over a 10C/50C (50F/120F) temperature range.

Witschi's Micromat C (http://www.witschi.com) features many interesting "features". It's basically a microphone on a motorized support with a built-in time base and embedded processing. All collected and processed data are sent to a PC via an USB interface. The WiCo Trace software (also from Witschi) automatically drives the motor, moves the watch dial up, dial down, etc. and collects data from the watch being measured. That's great. However, a 35 years old Vibrograf is usually still a good tool today. Will a Micromat be the same 35 years from now? Maybe. Time will tell.

Which machine is the benchmark for the watch industry? I'm sure _john is most entitled to reply to this question. I can only point you to a 2005 post (Benches, by Curtis for David Lou, Part 1 and Part 2). You'll see Vibrograf, Elma, Witschi (the flagship Chronoscope model) on various great watchmakers workbenches.

// slurrp

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Very interesting, thank you for the detailed reply...more questions..
Apr 05 2008,13:27 PM

does the machine require to be calibrated after a year of use?

I wonder, for the professional service centre, do they have a procedure using several calibrated test samples (watches) to verify their machines periodically?

Kong

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Actually yes,
Apr 06 2008,06:12 AM

Hi Kong,

does the machine require to be calibrated after a year of use?
In short, yes.
International laws apply to the professional workshop. As far as EU and US are concerned, all measurement and test equipment must be periodically calibrated according to specific standards and rules. To this aim, all professional timing machines feature a calibration procedure. Elma, Witschi and TYMC all feature an external time reference input (usually GPS synchronized) with which to calibrate their internal time base.

I wonder, for the professional service centre, do they have a procedure using several calibrated test samples (watches) to verify their machines periodically?
I hope they don't.
The most precise mechanical watch is far prone to aging - not to mention other sources of errors - than the simplest quartz circuit. You need a primary reference, such cesium, rubidium, GPS synchronized or radio controlled time base to calibrate your timing machine.

But if you don't need to issue officially certified results, then consider the following (can't swear on the math, but that's just to give an idea). The time reference in your timing machine is based on a quartz oscillator aging few parts per million per year, typically 5ppm/year (though Witschi oscillators are stated <1 ppm/year). That means that after 10 years your instrument will have accumulated an error of 50 ppm (worst case). As a reference, if your watch gains/loses 1 sec/day, that's a 12ppm error.

What does it mean? That after 10 years, in the worst possible case, your instrument will read +/-5sec/day for a perfect watch with a zero rate error in all positions (and a Witschi will reach this condition in 50+ years). If you take into account that:

• day/night temperature variations might introduce some error even on today's balance/spring assemblies (gain/loss in the range of few seconds per day - 2/3)
• just wearing the watch introduces your "personal error" (gain/loss in the range of few seconds per day - even 10)
• relative measurements (beat error, amplitude, positional error) are negligibly - if at all - affected by aging

then you'll happily live with your uncalibrated timing machine for decades

// slurrp

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Appreciate the reply, slurrp...thanks. [nt]
Apr 06 2008,21:59 PM

No message body

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Witschi is pretty much the industry standard now, Vibrograph formerly (nt)
Apr 04 2008,17:10 PM

nt

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Thanks _John. [nt]
Apr 05 2008,13:28 PM

No message body

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A little test showed...
Apr 06 2008,11:59 AM

Last year at the Basel Fair I tried putting my watch on all the timing machines I could find.  Of course I could not tell if the indications they gave were correct, but with the noise of the hall where there are lots of people and machine tools running demonstrations etc. I found there are big differences in the selective sensitivity of the transducers.  The Witschi was the best, rock solid, never a problem.  All of the others had more or less problems with surrounding noise.  I don't know what that says about their quality in general, but it gave me the impression that Witshi is the top of the back.
Don

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Did you get one?
Jul 11 2008,05:13 AM

Hi Slurrp,

I am curious, did you get one?

I am looking at buying a mchine and my heart says WITSCHI.

I wonder, where can I find best deal for that one?  I am located in Israel.

Thanks,

Saul.

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