My PO was running a little fast lately at about +10s per day. I sent it to the swatch service center and got it back 2 days ago.

I was given pre and post adjustment rates comparison slips... the staff at the counter told me the PO was magnetised and is now keeping 0.7s per day after degaussing. She also circled the rate on the slip for me... based on my own observation over the last 2 days, it seems to have gained 5s.

Could anyone please help me understand how to read the information on the slips?



Thank you

 

Compare the results on the bottom slip to the ones on the top slip. It appears your watch was running at +7.34 seconds per day (average of the three "X" results). After adjustment it appears to be running at +0.8 seconds per day (same math on the bottom slip).

If I'm doing this wrong, somebody please chime in and set me straight. Just be gentle.

 

To be clear, they test the watch in several positions as it will keep time differently depending on how it's oriented. I believe that the value in degrees is the amplitude of the movement, though don't quote me on that...

 

Your now in spec, and everything that was said above. Leave your watch in a different orientation over night and I bet it will keep better time.

 

No, that's not how you read this slip...there's no need to do any math as it's all been done for you. The left side of the slip shows the daily rate, balance amplitude, and beat error for each of the 5 positions tested.

The right side of the sheet shows averages and deltas. Note that any number with a vertical arrow pointing upwards beside it suggests that the number is too high, and if it were pointing down it would suggest the number is too low.

Starting from the top on the right side of the first slip, D is the Delta, which is the difference between the fastest and slowest position - this is in my view the most important timing number and it's good at just 4 seconds. Next number down X is the average of all 5 positions, and it's fast at +9.4 seconds per day. Next is Xv and Xh so average of just the vertical positions, and then of just the horizontal positions. Then Dvh is the Delta of the average of the vertical positions to the average of the horizontal positions, and Dv is the Delta of just the vertical positions. The next column over is all these same numbers for balance amplitude.

Not sure if the watch was serviced or simply adjusted, but I'm assuming the latter given the time between these slips.

The second slip now shows a better average rate (closer to zero) but a significantly larger Delta number, so whatever adjustment was done, it has added positional variation to the watch - not a good thing generally. If you look at the Dv numbers before and after, you can see that most of the extra variation is between the vertical positions, and this likely comes from the watchmaker not moving each timing screw on the balance the same amount when they were doing the adjustment, so they have introduced a poise error in the balance while doing this work.

Having said all that the variation is still just 7.4 seconds, and the watch is allowed to have as much as 12 seconds variation over 5 positions, so it's still within spec.

Note that the rate being 10 seconds a day fast likely had nothing to do with magnetism.

Cheers, Al

 

I do love getting an edumacation from folks with real knowledge! Thanks!! Even an old dog like me can learn new tricks.

 

Thanks to all who have commented. I've learned a lot, particularly from Archer's post.