JLC models moonphase accuracy question
I have duly completed my research but the findings are broad engineering concept and not specific information on the particular JLC models with moonphase. This accuracy information is not listed in the technical details section of various models on JLC web site. Could someone with familiarity of this moonphase wheel teething please fill in the blank for me? This curious mind begs you. It is not a quest for the ultimate mechanical supremacy. Rather, it is a case of getting to know one's own possessions better, if I can put it that way
MUT Moon 39=59 teeth?
Master Calendar=59 teeth?
Grande Reverso Calendar=59 teeth?
MUT Perpetual=XX teeth?
Master Eight Days Perpetual 40=XX teeth?
Duomère à Quantième Lunaire=XX teeth?
Thank you very much for any information you can share.
As an aside, I don't know how many teeth there are on the moonphase wheel of the Atmos clock. But surely there must be a whole lot of them given the large size of the clock relative to wristwatches. The JLC web site still lists moonphase accuracy for the simple Atmos model at one day deviation in 3,821 years (http://www.jaeger-lecoultre.com/AT/en/watches/atmos-classique-phases-de-lune/5112202#/t1). How appropriate for the Atmos...
Ruckdee
I asked for the Duometre à QL... It is the short version.
I mean, with a 2 to 3 years accuracy.
If I remember well, the Master 8 Days Perpetual is 122 years accurate.
Best,
Nicolas
No problem. Will patiently wait to hear the definitive word on that. Thank you. [nt]
The perpetuals are the same module...
and are the 122-year variant. The Duometers are, like the Master Calendar and the Duometers, 59 teeth.
-Dean
Many thanks to both of you. Now it is easy to remember.
Ruckdee
Moon Phase module
Quote:
That new movement was not to have any ordinary moon phase indication. Traditionally, most watch companies used what is called a 59/2 wheel ratio, since that shows a new Moon every 29.5 days and is relatively close to the "true" 29.53 day moon phase cycle. However, a 29.5 moon phase gearing produces an error of the moon phase being "off" one day every three years. That traditional 59/2 gearing also was what IWC used in its Ref. 5250 pocket watch and the Ref. 5251 Portofino Moon phase.
But for his new movement - first used in what is known as the Da Vinci perpetual - Kurt Klaus wanted to achieve even greater accuracy. Because all date functions were integrated, it would be difficult to correct the watch calendar, especially only the moon phase indication, every three years. Consequently, a much more complex gearing was developed and the new movement showed a new Moon once every 29.53125 days, or remarkably an error of one day in every 126 years!
Here is a more detailed article:
Before the days when computers were used for movement design, using a calculator Klaus developed a different gearing approach for the moonphase. Instead of one 59 tooth wheel that resulted in 29.5 day cycles, a series of wheels would produce a 29.53125 day cycle. The specific formula was:
This produced a difference between the synodic month and the indicated moonphase of .00066 days or 57.024 seconds. As a result the moonphase indicator would be "off" one day approximately once every 126 years. The precise gear design would be the following:
Sorry for the late response. I was traveling and also sick.
Ruckdee