A new Sub-c runs faster on wrist than on all resting positions

[Fredwatch]

Background story:

I bought a new Sub Date from an AD and it was within -4 to +6 sec/day in the first 10 days, but when resting positions only (dial up, crown up/down, six up/down). However, it was +40 to +80 sec/fast when wearing on wrist in the first 3-4 days and went down to +6 to +20 sec for the remaining 6 days.

I returned to the AD who has an in-house Rolex certified watchmaker. He put the watch on a machine and said the amplitude was too high and recommend to have it repaired by him. He said continuing wearing without repair will damage the movement. I picked up the watch after 3 days and the watchmaker said he replaced some metal parts including the mainspring.

Now:

It runs a few seconds slower than before. It is -1 to -5 on all resting positions. However, it is still +5 to +6 when wearing on wrist.

Questions:
Why is it so much faster when wearing than on resting positions? I thought COSC measurement is based on 5 positions that mimic the normal wearing. So isn’t it the accuracy number (when wearing) an average of those numbers from the 5 positions? But in my case, it’s faster by a big margin.

Should I be bothered by it and return the watch to a RSC for a thorough check-up?

A lot of sayings that a new watch usually runs faster but will slow down over months after breaking in. Is it true for Rolex, especially with the Parachrom hairspring?

[ExpII]

My Milgauss (bought brad new) ran fast when new then slowed down to -1s/day on my wrist. It hates the winder and rebels but I've learned to deal.

My advice, see how it's running in a few months then decide what you want to do. And make sure you wind it, I hear that's a pretty big deal.

[handsfull]

It is RARE to see the amplitude off that much from the factory. I am very surprised that the in house maker didn't correct it on the spot!

I would ABSOLUTELY send it back to RSC....no doubt about it, making it clear that your not happy/disappointed.

[Fredwatch]

Thanks for the responses. May I also have anyone with watch repair and technical background to share their views? If no, I will give a month time and to see if situation change before sending to a RSC.

[handsfull]

Originally Posted by Fredwatch

Thanks for the responses. May I also have anyone with watch repair and technical background to share their views?

Your welcome, glad to help. I possess both.

If your amplitude is indeed off (as the watchmaker stated), it is highly recommended you correct it. Ask to see the graph paper (see pic below). A competent watchmaker can address it, but not for free....Send it in to RSC.
Let us know what the results were.

[Fredwatch]

Thank you Handsfull. That’s exactly the watchmaker said that the watch had to be fixed right away. So I let him do it, I did not ask for the print out tough when getting it back.

The watch is now running -2 to -5 sec on all resting positions and +4 to +6 sec while on wrist (all measured over 12-hr period). I wear the watch from 6am to 6pm and put it down overnight. Because of the opposite deviation, I'‘m now getting -2 to +2 accuracy every day on "self-regulating” basis. Is this acceptable or does the wide deviation (max. 11 sec gap) still pose a concern?

[handsfull]

Short answer = yes. +4 to +6 with a FULL wind and being worn is acceptable.

Longer answer = there are many variables. I'm assuming your numbers are accurate, what are you timing it off of/How accurate is your source timer? (no offense) how accurate are you in your timing? When wearing it to work, do you sit at a desk most of the time, as people who sit at desks generally have their watch resting at the '12 down' position (if their wearing it on their left hand). There are more variables to account for, but I'm just stating these as examples.

Fwiw: The SubC paper in my pic is mine. If you have yours timed, it should yield similar results. The Numbers circled on the bottom of the paper are the mean/average of all positions.

[Fredwatch]

I’m timing off from timeanddate.com. I wear on my left wrist and I work on desk. So mostly the watch is on either dial up or 12 down positions when I’m working on keyboard.

I’m fine with +6/day when wearing on wrist. However, I’m puzzled by the fact that the deviation on wrist is much greater than when the watch is in all 5 resting positions.

I assume that the COSC spec of -4 to +6 range is measured from 5 different positions that mimic a watch being worn on wrist as in real life. So the actual “on-wrist” deviation should be an average of all the positions. In my case, the deviations on 5 positions are 2 to 5 sec slow but the watch runs the opposite direction of having 4 to 6 sec fast.

[handsfull]

To sum it up: Yours is 'within spec', but could it be better? = IMO Yes. Would I send it back to RSC? = Yes, their makers regulate the 3135 daily and should be able to optimize the potential of your movement/and you'll feel better knowing its been there.

FWIW: Given the results from my graph, mine runs +-0 on the wrist.