Some questions about regulation of watch movement

[DaveInLA]

Hi, got my first Rolex a couple weeks ago, and I also have some questions about accuracy and regulation of COSC models (Explorer I in this case).

Mine seems to run 5-6 seconds fast after 2 days, which is well within spec. However, my cheap Seiko auto is only 2 seconds fast during this time (with regular wear). Will RSC regulate my watch the way it is now, or only if it falls out of COSC limits?

About self-regulation, I've noticed that the Seiko will become less accurate as the power reserves starts to dwindle. That is, a regularly worn watch will be very accurate, but if I let the watch sit for 30-40 hrs without wearing it, the accuracy falls dramatically. Is Rolex the same?

About position, the Seiko is also very position sensitive. I know the old Rolex models came with instructions on self-regulation with regard to position of the watch when not worn, but my new Explorer I did not. Does that mean that newer COSC Rolexes aren't very sensitive to this? Thanks!

[Tools]

Dave,

A mechanical watch is designed to operate within a "power band" and that is probably in the upper 2/3 of the mainspring wind.

So, when your watch if actually fully wound, it will be a bit slower than while within the main power bandwidth. When the wind is quite depleted, it will be faster momentarily because , all other things being equal, the parasitic drag of the mainspring itself, and torque on the gear train is less; so the amplitude increases slightly..... If you keep in the power band, the fast and slow equal out and it stays, on average, within COSC...(at least that's the theory)

Now, lifestyle also plays into a watches accuracy since movement will also affect the rate or amplitude of the hairspring as it oscillates.

Yes, if you are not satisfied, and you take careful measurements over about a month to catalogue your wearing habits, Rolex will regulate it for you even if it is within COSC.. But your wearing habits and what you want is important to get it right. If you just send it in and say "regulate this", they are likely to put it on the machine and say that all is just fine.. They need to know that you want it a couple of seconds per day slower than it currently is.

But....do not decide how accurate it is until you have worn it for at least a month... Then chart it's acccuracy for a couple of weeks using an accurate reference and standard.

[Broke]

Originally Posted by Tools

Yes, if you are not satisfied, and you take careful measurements over about a month to catalogue your wearing habits, Rolex will regulate it for you even if it is within COSC.. But your wearing habits and what you want is important to get it right.

Not to hijack the thread, but would this info also apply to a 1966 Oyster Perpetual?
I've purchased the watch for my wife, and every week or so, it is slow by 4-5 minutes, but it is consistent in how it runs, so I thought I would only need to have it adjusted to run a bit faster than it is now. It is an 1161 movement in a 3/4 size watch.

I contacted the place I bought it from, but they said 34 secs a day is about normal for that age... but if it is adjustable, I don't understand why it couldn't be sped up, if nothing else, to compensate for the age and it running slowly

I just wanted to check to see if there was something I am missing before I ask about having it adjusted under warranty.

Thanks!

Brian

[DaveInLA]

A month, eh? I guess I'll track it for that time. It just boggles my mind that a $100 Seiko has the Rolex beat.

I think I've read that an auto watch with low power reserve tends to run faster, and this seems to be true in the Rolex (and consistent with what you said). But as I mentioned, my Seiko seems to really slow down when power reserve is depleted. It went from +8 seconds to -40 seconds after 40 hours of non-use.

[Jedi]

The $100 Seiko probably does not have the Rolex beat, literally. The workhorse Seiko movement, the 7S26 beats at 21,600vph, while the Rolex 3130 beats at 28,800vph. For this reason, the Seiko is more prone to positional differences in rate while not worn. the higher the speed of the balance, the better the stability in theory.

28,800vph movements are subject to positional correction too, but in a much subtler way.

[Tools]

Brian,

There is no reason why your 40 year old Rolex cannot run consistently within a few seconds per day..

First, ensure that it has been serviced properly within the past few years.. if not, that is your first step.

After that, making an accurate record of it's accuracy is important to have it regulatd to your wearing habits. If your watch is consistently off by the same amount each day, there is usually no reason it can't be regulated to run within an acceptable standard.

Early watches (before COSC in the 70's) are considered 5 second watches, but modern watches (post 70's) should be considered 2 1/2 second watches and that is what to expect for accuracy at the outside.

[SPACE-DWELLER]

Dave,

your quite right that modern Rolex movts. do not correspond much to the "Positional Correction" rules that you find a chart over in the FAQ's.

Still, the "Crown Down" position does tend to have an effect on any mechanical movt.

So if your Rolex is gaining time, try placing your watch on the crown during the night. It might slow it down a couple of seconds.

Also, as Larry stated, your watch needs to adjust to your wearing habits. Furthermore, you would want to check how many hours a day you are wearing your Rolex. To get sufficent power reserve and thus consistant timekeeping, you would need to wear your Rolex 8 to 10 hours a day at a minimum.

Having your Rolex regulated is an easy operation and can normally be done by an AD watchmaker while you wait.

Here's a good article by Sheldon on how the Rolex is regulated:

Regulating A Rolex.

[Broke]

Originally Posted by Tools

There is no reason why your 40 year old Rolex cannot run consistently within a few seconds per day..

Thank you for the reply. I have started a log to keep track of exactly how slowly it runs. I'll watch it for about a month or so, and then look into having it regulated.

Does the 1161 movement have microstella screws to regulate the movement as shown in the DIY article that was posted?

Brian