# 21600 vph - is that good, bad or average?



## mamadubwana (Oct 2, 2008)

Hi,

I have an Aviator watch which has a mechanism (Poljot 2623) frequency of 21600 vph. Is that good, bad or average, what does this frequency tell me about a mechanical watch and is there some article I could read which would educate me about this aspect of mechanical watches?

Thanks,

M


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## JimH (Jan 15, 2007)

The beat frequency of a watch is not a measure of its quality.


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## mamadubwana (Oct 2, 2008)

JimH said:


> The beat frequency of a watch is not a measure of it's quality.


ok. then what is it a measure of? It is indicated in the technical specs like something relevant to the customer. what are these frequencies all about? should I care about them? what would be a low or a high frequency?!
:-s


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## vardjuin (Feb 14, 2008)

low 18000 - high 36000
this ensures a higher accuracy but affects the durability of a watch.
low rate (18000) less accuracy more durability. high rate (36000) more accuracy less durability.


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## JohnF (Feb 11, 2006)

Hi -

The speed of the movement is measured by the number of oscillations the balance wheel makes. The more of these it makes, the larger the number of sub-second ticks of the watch; the more of these, the danger that a single tick (or more exactly, a recurring single tick) that is off in terms of accuracy (due to, perhaps, a missed rough edge on the escapement wheel) will affect the overall accuracy of the watch.

But it's not so simple: the characteristics of the balance wheel - its material attributes, how well it is balanced, etc. - have a lot to do with the accuracy of the watch. The diameter is critical as well: part of the energy from the mainspring is imparted to the hairspring on the balance wheel, and in the high-speed movements, the balance wheel is usually quite small and cannot be adjusted easily outside of the factory (a watchmaker can remove material to re-balance, but that is destructive and it's usually much better to simply replace the assembly with a new one from the factory, if this is available).

There are other issues with the higher-speed movements: lubrication is the major problem. The forces involved on a 36'000 bph watch overwhelm normal watch lubricants due to centripetal force (not to be confused with centrifugal force!), forcing the use of special, low-viscosity lubricants that are not normally in the watchmaker's inventory.

A very high-end low beat watch may have significantly greater accuracy than a moderate quality high beat watch due to a balance wheel and hairspring that are perfectly matched, while the high beat watch uses a balance wheel and hairspring that are merely adequate. The higher the beat, the more important apparently small variances become, since they are multiplied by the higher beat. Getting the beat up to 36'000 was a challenge: while there is a movement that moves at 360'000 beats (as a separate movement in one of the chronographs in order to provide 1/100th second accuracy), it is a movement that drains the separate mainspring completely within 5 minutes, making it a mechanical marvel that is fairly useless.

Watch movements are never quite so simple as they appear... 

JohnF


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## NEG (Aug 11, 2006)

Pinched a quote from timezone that may be of interest:

_On the subject of beat rate it appears that there can be no objective consensus, but I will try to point out the pros and cons of the two philosophies, and the reasons behind manufacturer choice:_

_The advantages of fast-beat (28,800 v/h and 36,000 v/h) are obvious: better isochronism, and better performance in both vertical and horizontal positions even with minimal adjustment or no adjustment at all -- one of the reasons fast-beat has been almost universally adopted by mass-producers. In fully-adjusted fast-beat watches positional adjustments are naturally less laborious. _

_The disadvantages are the insidious problems of greater friction, stress, and wear -- not just on the escapement where it is obvious, but throughout the wheel train and in the winding systems of automatic movements. For best isochronism it is vital that a watch only run during the flattest part of the mainspring's torque curve. This is why a movement that is expected to be fully re-wound every 24 hours is typically given a 48+ hour power reserve; only the first half of it is meant to be used. _

_A high beat rate uses power more rapidly and thus requires a stronger mainspring to get adequate power-reserve and thus best isochronism. This increased torque output puts greater stress on all of the pivots throughout the gear train as well as increased friction between wheels (wear). Anyone who has hand-wound a fast-beat Zenith chronograph knows that the winding is relatively "stiff" due to the strength of the mainspring. For automatic winding this requires extra high-mass rotors, and the winding train suffers greater wear as it is caught between the resistance of a strong spring and the high winding force of the rotor. _

_Taken all together, this means that fast-beat movements have shorter service intervals, and the greater rate of wear necessitates more frequent parts replacements. Prominent proponents of fast-beat rates include the manufactures: ETA (and Valjoux), Seiko, Rolex, Zenith, Jaeger-LeCoultre, Glashutte Original, Chopard, and Parmigiani Fleurier._

_The advantages of slower beat rates (18,000 v/h, 19,800 v/h, and 21,600 v/h) are less immediately tangible. Lower power needs allow for soft mainsprings, limiting stress and friction throughout the wheel train, winding train, and the escapement. Service intervals are longer and more flexible, and parts replacements are rare -- extending practical and theoretical longevity of the movement. _

_The disadvantages are far more tangible: As was noted above, a slow beat movement will generally not perform as well as a fast-beat one, and while slow beat movements can perform very well it requires more skill and effort from the watchmaker to achieve, primarily through laborious positional adjustment. Thus slow-beat is embraced primarily by manufactures of high-craft movements, most of whom consider 21,600 v/h to the best compromise -- with measurably better performance than 18,000 v/h and with much less wear than 28,800 v/h. _

_Prominent proponents of slow-beat include master watchmakers like George Daniels and Philippe Dufour, and manufactures like Patek Philippe, Audemars Piguet, Frederic Piguet, IWC, Roger Dubuis, and A. Lange & Sohne, and slow-beat accounts for most of the movements produced by Nouvelle Lemania._


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## NEG (Aug 11, 2006)

Excellent article on fast beat movements:

http://montresuisses.blogspot.com/2006/12/longines-ultra-chron-movement-calibers.html


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## lysanderxiii (Oct 4, 2006)

Some people decided that they should use beat rates up around 64,800 or 72,000 bph , I have been able to get an accurate count.


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## JimH (Jan 15, 2007)

Beat rate is listed in the technical specifications because it is of interest to a watchmaker in setting his timing machine when regulating the watch.

High-beat rate movements have the _potential_ for somewhat better accuracy/stability than lower beat rate movements but remember that there are 18000 BPH chronometer-rated movements.

The highest beat rate for wristwatch movements is 36000 BPH but the only movement currently in production that I can think of running at this rate is the Zenith 3019 "El Primero" chronograph. Higher beat rates are used in timers to break a second down into more parts but these movements are not designed for continuous use.

I don't take beat-rate into consideration at all when considering vintage watches.


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## mamadubwana (Oct 2, 2008)

Dear friends,

Thanks A LOT for this fantastic "deluge" of very interesting explanations! I really appreciate you taking the time to explain these things to a newbie ignoramus like myself. I have to admit that I am totally fascinated by the mechanics of watches. Not only interested, which I am, but really *fascinated*, no other way of putting it. Is there a book for a newbie like myself, maybe a "mechanical watches for idiots" or a "beginner's guide to mechanical watch movements" or even a "a basic history of mechanical watches and their movements"?


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## Eeeb (Jul 12, 2007)

A site for the collectors of High Beat movements... http://36000bph.com/

This topic certainly got our blood circulating!!


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## Eeeb (Jul 12, 2007)

Are there any common timing machines that will operate at these bph?


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## JimH (Jan 15, 2007)

Eeeb said:


> A site for the collectors of High Beat movements... http://36000bph.com/
> 
> This topic certainly got our blood circulating!!


Yes, that's an interesting site. It's surprising to me also that this topic drew so much interest! :-!


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## glenns (Aug 12, 2011)

JimH said:


> I don't take beat-rate into consideration at all when considering vintage watches.


That's like saying you don't take handling into consideration when buying a vintage sports car.


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## dacattoo (Jan 9, 2011)

Start with a book that will answer the question why is an accurate timepiece necessary. The book is an easy read and was even a movie on PBS. It is a remarkable story of a carpenter and the first watch ever made (partially of wood) accurate enough to sail the 7 seas. The watches still exist today and still work (Royal Observatory in London) although they are centuries old. The name of the tome is "Longitude".


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## lysanderxiii (Oct 4, 2006)

glenns said:


> JimH said:
> 
> 
> > I don't take beat-rate into consideration at all when considering vintage watches.
> ...


 No, it is like not taking in to consideration the size of the wheel rims when buying a vintage car....


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## clock40man (Nov 2, 2009)

Eeeb said:


> Are there any common timing machines that will operate at these bph?


My Microset can be used with virtually any bph.


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## clock40man (Nov 2, 2009)

mamadubwana said:


> Dear friends,
> 
> Thanks A LOT for this fantastic "deluge" of very interesting explanations! I really appreciate you taking the time to explain these things to a newbie ignoramus like myself. I have to admit that I am totally fascinated by the mechanics of watches. Not only interested, which I am, but really *fascinated*, no other way of putting it. Is there a book for a newbie like myself, maybe a "mechanical watches for idiots" or a "beginner's guide to mechanical watch movements" or even a "a basic history of mechanical watches and their movements"?


The Complete Price Guide to Watches by Cooksey Shugart (and others) is an excellent resource to have. Lots of good information about wristwatches and pocket watches. I have a "suggested reading" page on my website.


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