amanico
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A view on the JLC Cal 899: The Balance Wheel and the Escapement. A lesson of accuracy
While reading the title of this article, you may think that it may be a bit too technical, or abstract.
In fact, the balance wheel and the escapement are among the most important parts of our beloved watches.
Indeed, they are THE sine qua non condition of the... Accuracy of a movement.
Precision... That is a relative notion, for our mechanical tic tacs, since any Quartz movement will beat the best of them.
But Precision is to watchmakers what Eternity is for Humans, a kind of Grail Quest.
When we think accuracy, we have Chronometry in mind.
Here again, since Chronometry is necessarily submitted to the intervention of an external autorithy, we have to wonder if Chronometry is the panacea.
Let's compare the COSC to the 1 000 Hours Control, for example.
Is the COSC better than the 1 000 Hours Control? Certainly not.
- The COSC is testing the movements for 15 days before they are housed in the watch.
- The COSC tests the movements under 5 different positions and three temperatures.
- The Certificate of Chronometry is given to movements which work in a - 4 / + 6 seconds per day range.
The 1 000 Hours Control is, of course, longer ( 41 / 42 days ) and more demanding.
THE big difference is that the movement is adjusted once ENCASED, and, to be more precise, 24 hours after the movement is encased.
Why? Because when you tighten the screws during the " installation " of the movement in the case, there are some physical forces which may influence the good work of the movement.
That being said, let's go back to the Balance Wheel, the Escapement, and the incidence of the automatic movement.
1/ The Balance Wheel:
To better understand the technical interest of the Cal 899, let's first have a look at the manual winding movement, housed in the Geophysic.
You have a racket, a swan neck, and perpendicularly to the racket, a big screw crossing the swan neck.
This is this big screw which makes the racket move, while the utility of the swan neck is to maintain the racket in position in case of shock.
The problem is that it is extremely difficult, with this system, to achieve a fine, precise tuning of the movement, since you get variations of + / - 10 seconds.
On the Cal 899 Balance Wheel, you have 4 screws. An adjustment will require to turn the screws in a certain angle, knowing that the minimum is to do it on an opposite pair, ideally on the four.
This way, you will gain ( by moving the screw inside ) or loose ( outside ) one second, one second and a half.
Of course, that will require that your balance wheel is perfectly balanced. If it is not the case, drilling ( slightly ) the balance wheel will be the ultimate resort.
The Balance Wheel of the Cal 899 ( without the automatic parts, which have been removed for the photo ) :
If you want a fine setting, then you will have to work on the screws, again. The watchmaker told me that they can easily get an accuracy of 5 seconds per... week. Another factor has to be mentionned here, which is too often ignored: The wearer of the Watch.
Since the rythm of our lives is different from one person to another, the Watch can gain or loose time. Jaeger-Lecoultre advises that, after a while, one month or two, if the Watch still runs too fast or too slow, it has to be adjusted, once again.
2/ The escapement:
The escapement is composed of an escape wheel and a pallet fork, which are, of course, in relation.
This is another important part of the movement, since it influences the good work of the movement through the Amplitude.
A good amplitude will provide a regular work of the movement. It will then affect the accuracy of the watch.
If you have a problem of amplitude, then you will have on other choice to set the escapement, the relation between the pallet work and the escape wheel.
Here is the pallet fork, the escape wheel, the balance wheel with its hairspring mounted on its dedicated bridge, removed from the movement, from right to left:
3/ The Automatism:
On a manual winding watch, when the movement is fully wound, the amplitude is perfect, but the closer we are to the end of the power reserve, the worst it is for the stability of the watch.
With an automatic movement, this problem doesn't exist, since it is always " fed " by the rotor.
Hence, we can say that the charge is constant, allowing a regular work of the movement, then, a better accuracy.
The Cal 899 with its automatic parts:
What has to be said, too, is that like in any collective sports, you can get some excellent parts, but if you don't know how to make them play together, you will not get good results.
That is all the talent of the watchmaker to assemble these parts, and to set them properly.
That is all the Raison D'Etre of a true manufacture, to intimately link The Man to The Product. The Man, at the Service of The Product, The Product at the service of The Man.
Please forgive my approximative horological descriptions, but at least it will help to better understand the accuracy of our dear watches.
Best,
Nicolas
This message has been edited by amanico on 2015-01-07 00:03:28 This message has been edited by amanico on 2015-01-10 10:11:16
More posts:
A view on the JLC Cal 899: The Balance Wheel and the Escapement. A lesson of accuracy
While reading the title of this article, you may think that it may be a bit too technical, or abstract. In fact, the balance wheel and the escapement are among the most important parts of our beloved watches. Indeed, they are THE sine qua non condition of...
What a beautiful caliber...
Hello amanico You had me with the dis-assembly photos. So many things effect the accuracy of beloved timekeepers. Kind regards Anthony
Thx a lot for this comprehensive & educating write-up.. Actually read it 2x .. :)
.. to better look behind ! For me indeed quite instructive - have bookmarked this one ! One Q, pls : what are the extremes for the temperatures tested ( let's say for the 1000 hrs) ? Fluids & oils may change their viscosity, but maybe that occurs already ...
Hey Nicolas, Thanks For A Very Informative...
... Post. The insight you provide makes us all appreciate these examples of living art that much more. Best, My Friend! - Scott
Cal 899 (manual) is amazing!
How old is it? And by the way I like technical reports, it's good to know what's inside. Thanks, Constantin
Early 90ies for the Cal 889. 1992.
That it became Cal 899 in 2002. I am not at home, so my answer is from memory. Best, Tudor. Nicolas
Funny: I just stumbled in my studies over this caliber today!
I was browsing on the internet and stumbled over an article about accuracy and this JLC 899 was amongst four praised ones for great accuracy. What I have learned today, again, is that accuracy is depending on everything in a watch to achieve a smooth tran...
Yes, Moritz, the watchmaker I met insisted a lot on that point.
Precision, more than accuracy, dépends on the owner's lifestyle. A Watch is accurate if it looses or gains 20 secs a day, if it is regular. A Watch is precise when it is within the choronemetric tolérances. That is the difference I make. And yes, you are ...
Chronometry competition: looked it up ...
... and cross read it only an will read the full article tomorrow: it was "even" an ETA 2824 from Tissot that ranked super high :-)! Many thanks for the research tip! Moritz
2824 was also used by Longines for their Legend Diver and Tudor for the Black Bay.
A tractor, reliable and accurate. Best, Nicolas
... and a tractor deluxe in its elabore grade
I knew of the qualities from the 2824 and the 2892 and that it is widely used in the watch world. But to read how good the 2824 was in the contest is really cool! Another, of topic movement, I came across today is the Buren calibre 82. With 36.000 beats p...
No, I don't know. But I share your enthusiasm on these movements which are too often ...
" Snobbed " while they have some excellent horological qualities. Now, there is one thing to add, while we are at it. The outcome, in these Chronometry contests ALSO dépends on the talent of the watchmaker who finely adjusts the movements. Of course, a ba...
Thank you Nicolas!
And let me end on a final note: the other two praised movements, next to JLC 889 and ETA 2892, were Rolex 31xx and ETA's Valjoux 7750. All four are for themselves a primus inter pares for the knowledgeable watch fan and my todays studies just confirmed it...
Yes, Moritz...
That is why I am always laughting when I sometimes read " Well, this is too bad it is only an ETA 28xx or 77xx " and so on... I rarely read that people complao about Rolex movements... Funny, isn't it? I didn't read that people didn't like the 899, tough....
Thank you for turning our attention to the technical details
I love it to care about these details and about these core diciplines of watchmaking. For those who would like to dig a little deeper: This post reminds me about an article that Jaw wrote about the Autotractor movement cal 97x in 2004. It can be found her...
Thank you for this most interesting technical article dear Nicolas...
... well written and explained for someone with non technical knowledge like me. I always wonder at the accuracy of these little precision machines inside our beloved watches. Your article explains beautifully and I can´t stop viewing with awe these littl...
It is all the talent of the watchmaker who gave me that lesson.
To make something quite tough simple. No need to say that I did loose notion of time, while I was given these explanations. Tha,ks for your input and kind words, Abel. Un abrazo, amigo. Nicolas
Wonderful article, Nicolas! :)
Thank you for sharing these photos and insights! :) Very interesting and appreciated! Best, my friend Blomman
What a coincidence that we both decided to post a topic about accuracy!
Almost in the same time... ;) Thanks for your kind words, Blomman. Nicolas
Temperatures
Thank you Nicolas for a wonderful post. I have one question for you which hopefully you can help me to understand. How is that a watch can be adjusted in 5 positions, as well as adjusted for temperature s (plural, as it states on the plate of the JLC move...
That means you check how the movement works under different temperatures and positions.
If Under one specifci temperature or position, it doesn't work propelry ( ie you have a loss of amplitude, for example ) you have to re work on it. If the movement works correctly Under different températures and positions, there are chances that, in the ...
Update about the temperatures according to the 1000 Hours Control.
22° Celsius, then 4°, then 40°. Best, Nicolas
Your's and Mine, Cal. 899
Wearing my JLC Master circa 2011, for the Far East. Some dial differences, mainly layout and case dimensions. Otherwise the same. The cal. 899. I find it is running approximately +6 to 7 seconds per day. Nothing drastic and not sending it off to Texas for...
+6 /7 secs per day is good, especially if it is the case every day.
You can always ask to make it run slower. Best, Nicolas
Caliber 899 in a Master Control
I have a cal. 899 in muy Master Control with date. The only difference is that JLC manufactured this version, dial layout and case size, 37 1/2 dia., solely for its Oriental markets. Mine dates from 2011. I find that it keeps great and consistent time at ...
Dear Amanico...
My wife is about to gift me the Cartier Tank MC and I told her so hold off a day or two so that I can consider the JLC's Master Control Date. I have always admire JLC as a movement maker and won't mind adding them to my collection. Can you please share yo...
Is a date important for you? If yes, I would go for the Master Control. A good, reliable, serious watch. With a strong link to the Geomatic.
If the date is not important to you, then the MUT 34, 38 or 39 mm is the one to go for. You will add a big touh of class and elegance. Best, Nicolas
I see, but is it still in production? I dont think I saw that option while glancing through their site.
Also, my apologies if Im taking up too much of your time
No, at the exception of the Master Ultra Thin 40 mm date, champagne dial. I posted it a few weeks ago.
Still you can quite easily hunt a steel MUT 38. Best, Nicolas
JLC cal. 899
Excellent article. Owning a Masterpiece I can attest to what was stated.
