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The THEORY behind your comments are well noted (and known) with thanks. But...

October 20 2006 at 9:37 AM

ThomasM  (Premier Login thepurist178)
AP Discussion Group

Response to Reasons For The Vertical Clutch

Hi, Jeff,

I've long been fascinated (and obssessed by) the often wide chasm between theory and practice; between how things are supposed to work and how they actually work.

I'll let Suitbert, John, and others with bench experience and watchmaking schooling counter point the theory; I'm just a humble hobbyist who happens to understand a little bit of the theory, in theory, and more than a little personal experience with timepieces, accumulated over nearly 3 decades.

1. The ability to run the chronograph continuously. With "traditional" supplemental fourth wheel/intermediate wheel/center wheel chronograph train designs, the teeth on the center wheel are triangular in shape and very small and fragile. The teeth must be small and of this shape to minimize jumping when the chrono is activitated. However, this leads to substantial wear issues. I can't think of a single chrono of this design where the owner is not specifically advised NOT to run the chrono continuously because of wear. Vertical clutch designs permit constant running of the chrono if the owner desires.

This is the widely (universally?) accepted theory, one which makes perfect sense to me and which I have been aware of for decades.

In practice, I know a large number of watchmakers who have looked at hundreds of chronographs, some decades old and many which have had their chronographs continuously running most of that time. In many cases, there was no serious, operation effecting signs of wear.

Does this contradict or undermine the theory, then?

No, not necessarily; it could also have to do with the materials used, how that material was worked and treated, in the past, in different movements, by different brands, which makes the theoretical considerations mostly moot and a matter of internet "chat"

Conclusion? The theory is fine, but be careful of drawing non-sequitor and malapropos conclusions from it, either in praise or in damnation.

2. Rate keeping. The gear design produces on average around a 30 degree drop in amplitude when the chrono is activated. Thus rate keeping suffers. This does not happen with vertical clutches to anywhere near this degree and again the chrono can be left running with little effect on rate keeping.

I'd love to see statistically significant correlation and regression analysis of amplitude to rate keeping.

Of course every watchmaker and advanced hobbyist knows that amplitude is important, and within a certain range, big amplitude is better than small amplitude.

Simple truisms.

Again, in practice, I know of many examples where a timepiece with poor amplitude continues to exhibit incredible timekeeping "stability" (over minutes? hours? days? weeks? months? yes) even if the Witschi is sending off klaxon calls of "red alert! red alert!"

Ironically, this very topic came up recently in a conversation I had with Dr. Fabric Deschanel (Managing Director of Renaud et Papi; I would hope we can all accept HIS and THEIR credentials without too much fuss?) who proudly proclaimed that even with very low amplitude, their new AP modified Robin escapment was very stable and reliable.

Of course, to really think about that comment critically, it indicates the acceptance of the generally accepted theoretical assumption that high amplitude, within range, is good; but makes the practical point that those same practical results are possible with low amplitudes.

Conclusion? take theory with a grain of salt vis a vis how things actually work, and be careful of allowing theory to force conclusions about reality.

"That's not supposed to work; the theory says so!"

3. Start stopping. With gear designs it is a crap shoot how the teeth will land when the chrono is started. Sometimes fate smiles and the peak of one tooth happily lands in the trough of its mate. More often that is not true and the chrono hand will jump as a result. This is simply unavoidable. With vertical clutches, starting is essentially always smooth.

This is one of those "truths" that is so obvious, in theory, that it is hard to discuss, in practice.

Of COURSE if you throw an apple in the air, it will come back down.

But strangely, and I still don't understand why, as the reason is not obvious in the theory, I HAVE seen (and now will try to document) specimen of vertical clutches, including Blancpain chronos using the famous F. Piguet 1185, that DO jump on activation.

Go figure, eh?

Conclusion: see previous

4. Avoidance of needle flutter. Gear designs suffer from fickelness. Chrono second hand movement has a tendency to produce flutter, which is uneven movement. There are two techniques employed to minimize this. Most commonly a spring is tensioned across the chrono seconds hand shaft to apply resistance to it. This has the disadvantage in that reduces amplitude, effects rate and consumes energy. Alternatively the depthing of gear engagement between the center chrono wheel and intermediate wheel is increased. This puts tension into the train and at worst can stop the watch. I cannot tell you how many absolutely top of the line chronos I have seen that suffer from this flutter problem. This does not happen with vertical clutch designs.

I haven't specifically looked for this problem in vertical clutch executions, as I have the chrono hand jump phenomenon, so I won't comment. Again, the THEORY presents no problem, for me.

Like my experiences with adjustment and fit and finish issues with Blancpain watches, I was happy to keep my personal experiences to myself. Afterall, despite MANY (too many) problems I've personally experienced with sample numbers more than probably 95% of the general population (6 tourbillon variations, 3 repeaters, more than 20 more "basic" models, and these are just the ones I own/have owned for some period of time, and don't include pieces I know about or had brief experience with) I am/was still very much in love with the brand and their designs and products. And, I appreciate Blancpain's diligence in correcting the problems (though I know they too wish, like I, the problems didn't occur in the first place)

But when I read some of the claims and statements being made about and for Blancpain in the recent threads, I find it unconscionable to not counter point it with my personal experiences.

I really hope that presentations, especially conclusions and "truths," at least here on ThePuristS, are a bit more "real" and a bit more "balanced."

It's okay not to be perfect!


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