skyeriding
901
I'm fairly certain the hand impulses differ from example to example because of how it works
You're analysis is correct however - it does not measure the 1/100s linearly. In fact, the 1/100 scale can be arbitrarily replaced with a different number (like 1/50, or 1/200 etc).
Let's revisit the basics of how it works again, so we can understand about the hand alignment.
At heart, the Centigraphe is mechanically a 3Hz movement. Hence, it results in the 6 pulses (1Hz=2 pulses) of the foudroyante. Thus in theory, as a regular chronograph you can only measure up to 1/6th of a second.
However, the Centigraphe has a special vertical clutch mechanism that is able to intermittently release the foudroyante hand from the main geartrain, resulting in readings "in between" the 1/6th of a second. In the case of the Centigraphe, this can approximate a 1/100 scale as printed on the foudroyante dial. However, this is not a fully linear measurement as your graph demonstrates - this is because the "pulses" from the 3Hz means the time measurement is not fully linear.
Technically, a 50Hz beating escapement (e.g. like Tag Heuer) would allow for an accurate 1/100s measurement.
In ideal theory however, this sort of mechanism would work best with a true smooth gliding hand like e.g. the Spring Drive, since you can theoretically print as fine a dial scale you want. But, that is not a 100% mechanical solution...
Now, regarding the 5, 22, 38 etc readings, this will differ example to example - it is caused by the relative position of the pinion gear (that has six teeth) and hand installed onto it. I suppose that in the watchmaker's bench during construction, the mechanism is reset to 0 and the hand is fitted to 0s. Where it lands then depends on the orientation of those six pinion gear teeth that form the foudroyante mechanism. These six pinion teeth engage and disengage the main watch geartrain via the vertical clutch that is mentioned earlier.
This video demonstrates the mechanism, about 4 mins & 40 seconds in: https://www.youtube.com/watch?v=I6WW0vPQpG0&t=4m40s
This hand alignment I think is something that is a little beyond the watchmaker's control in a practical sense (it's almost akin to how a screwed down crown may not align the right way up, screwheads don't have a perfect angular orientation, or how the seconds hand sometimes doesn't fully line up to the dial).
(EDIT: Though, for a direct comparison the JLC Duometre Chronographs also has a very similar foudroyante mechanism, yet the hand always aligns to the ticks on the dial...)
(EDIT: Though, for a direct comparison the JLC Duometre Chronographs also has a very similar foudroyante mechanism, yet the hand always aligns to the ticks on the dial...)
Some examples where the foudroyante pulses at different ticks:
7-8 hundreds of a second
10 hundreds of a second
In my personal opinion, this is not a big issue since the mechanism can be stopped intermittently at any point; however, having a linear scale on the dial when the hand moves in an impulse I felt is a little misleading when the hand jumps in impulses... For average usage however, it shouldn't matter in a practical sense, as we humanely do not have that reaction time precision to measure that fine a timescale!
Regards,
skyeriding
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FPJ Centrigraphe movement - Foudroyante hand motion
Riddler's new purchase encouraged me to think about what is going on here. As far as I can tell from playing with this, it appears that the 100th hand is stopping at 1/6 s intervals. For each 1/6s interval the hand is still for 1/3 of the time and in moti...
I ve read the technicals right after our pal posted the
incoming thread,technically very interesting ,great that they set apart the time keeping and chrono your question i m tired to check at the moment.
Thanks My Friend.
I looked at slomo rate video of it so one can clearly see the 6 residence points. Yes it is true the device allows stoppage at any point, but the time measured will not linearly correlate with real time. I wonder why Journe chose these stop points of 5 22...
I'm fairly certain the hand impulses differ from example to example because of how it works
You're analysis is correct however - it does not measure the 1/100s linearly. In fact, the 1/100 scale can be arbitrarily replaced with a different number (like 1/50, or 1/200 etc). Let's revisit the basics of how it works again, so we can understand abou...