Quote:
Originally Posted by saxo3
Thanks for coming back here. I agree with what Scott (aka Watchmaker) wrote "High amplitude is not analogous to good performance of a watch" I add that its starting value and time dependance is a very good indicator of movement health, see several graphs in this thread.
Interesting "that lower amplitude contributes to longer power reserve". I can't confirm but would like to see measurement data for this.
Your SD43 came back from RSC Dallas in Dec 2019. Lift angle 55 degrees gave:
DU: 284, +3
CL: 253, 0
CD: 267, +3
CR: 253, +1
DD: 293, +4
Your data yield to X = +2.2 and D = 3, which is very good.
I don't understand why you measured in position CR = 12U and not CU = 3U. Is that right?
For a watch serviced by a RSC in 12/2020 it would be interesting if you could measure for DU the amplitude decrease with time, i.e. from full caliber winding (t = 0) to the end of the power reserve (t = 70-72 h) using 53 degrees lift angle.
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I’ll see what I can setup. Essentially, take measurements in the timing machine with the watch running over a 72 hour period (correct?)
I wish I could repost Nick’s article from his email list, but Nick and the TRF owner had a falling-out years ago (the things you pick up from following this forum for the last 300 years). Below is an excerpt that might help explain:
There are two 'powers' in the balance wheel system. The first one is the balance power, which is the amount of power presented in the oscillator, calculated as a product of balance inertia, amplitude squared and frequency cubed. For the Rolex calibre 3135, the balance power is 372 micro Watts. The second power is the oscillator maintaining power - the power required to keep the oscillator running. Again, for the Rolex 3135 that is 1.24 micro Watts. Fine tuning the ratio between the two is an engineering challenge because extending the power reserve by reducing the energy consumption of the balance wheel will come with a trade-off: degraded performance and poor timekeeping.
I am sure the Daniel’s watchmaking book would have more detail. I’ll dig it up and see if I find any better explanation.
On your question regarding CR position, I’ll have to go back to my notes as well. My watchmaker pal says that measuring CR is not an official position because in that position, you would have to hold the watch in front of your face all the time for that timing position to be meaningful and thus is not considered.
-Sheldon