skyeriding
900
Not to say it is "less complicated", but trying to get an insight as to its category compared to other similar movements
Sep 15, 2017,15:41 PM
I believe each complications have their own issues and adjustments required to work properly, and there should be a somewhat tangible justification of why a watch within a brand's catalogue may be put in a certain pricing category to justify its value. I assume a similar argument can be held for e.g. a 5370 vs 5959.
I am not undermining what a watch it is (undoubtedly, quite a marvel and rarity to even see one in the real - besides, no other brand I know off the top of my head makes a pure Celestial complication like this one!), but I'd like to understand it deeper versus rival complications. So far, from what I gather:
As Mark in Paris puts it, there is likely a very high precision required for the sapphire discs alignment/manufacturing/tolerances for it to function smoothly. There is a differential gearing mechanism for the moonphase, which adds a number of parts but however is not an uncommon mechanic in itself (used often for e.g. power reserve indicators). I also think quite some handwork is required for the case sides decorations. Add the research of skycharts/maps, correct gear ratios, etc. and I believe that has to warrant for the added value (and undoubtedly, the exclusivity of such a complication contributes to the timepiece value)
Here is a video that gives a glimpse of the underlying mechanism (as I couldn't find a picture of the movement drawings):
https://www.youtube.com/watch?v=uc8NsDqZ4OA&t=85s
For comparison sake, a perpetual that has less parts is not entirely surprising (the number of subdials aren't necessarily indicative either as you said - hands can simply be added on top of the gears hidden under the dial if they are in the right place, and a subdial to indicate the respective information). Nevertheless, there is still quite a fair bit of adjustment to function. Compared to just having a set of gears, a typical classic perpetual calendar like the 5140 consists of a "Grand Lever" and a "Program Disc", with some "Jumper" springs. I'm no watchmaker, but I believe some careful tuning is required for these variety of the levers and springs to get the mechanisms to function just right. A mechanism that has purely gears would negate this though - and would be more to ensure smooth rotation/meshing of the gears, and that the date/subdials are all coordinated.
Fo reference, here's a classical perpetual calendar mechanism by AP which a 5140 would function quite similar to:
https://www.youtube.com/watch?v=FeKShseDwM8
Perhaps a more comparable mechanism would be the Ulysse Nardin GMT Perpetual which purely consists of gearing mechanisms (which, has the benefit to allow forwards and backwards adjustment of the calendar at the cost of being non-instantaneous). A similar mechanic, yet different implementation might be the Lange Terraluna (which unfairly, is in yet a higher price category but has the additional instantaneous perpetual calendar mechanic. However, it also has an orbital moonphase display very similar to the 6102 - just without the sky chart).
Regards,
skyeriding