Hi guys, I have a question regards the various factors that might affect the daily accuracy of a mechanical watch.

My Speedy Pro (cal. 1863) has been running at a pretty constant +2sec/day since last December, when it was bought brand new from an AD. In the last 4 days or so, however, it's been running at about 3.5-4sec/Day.

What has changed? Well, I've gone from the slightly chilly, reasonably humid climate of the UK, to the quite warm, dry climate of Nevada. Not only is it warmer outside, but I guess the watch is subjected to more significant temperature changes, moving from warm outdoors to air con indoors. Also, the day I arrived, I banged the watch on a door frame, and from this point is when I started measuring. Could that be a factor? I know there's an element of shock protection in the balance, but would an abrupt bang affect the accuracy in such a way?

Obviously, +4sec/day is pretty good, especially as the 1863 isn't a COSC movement, but once you've had +2 per day, you know what your're missing! Just interested to learn a bit more about how they work, and see if I can possibly mitigate against the variation.

Thanks all, Max

 

In general, there are a lot of factors that can affect how a watch runs....from the state of wind to positional variation to temperature variation....then shocks, magnetism, etc.

In this case, it's likely just positional variation. The Speedmaster Pro is not a COSC watch, so it has very generous running tolerances for accuracy. Since it's not COSC, it is only measured in 3 positions instead of 5 that a COSC would be checked in. Over those 3 positions at full wind, the watch can vary up to 15 seconds. At full wind -24 hours, it can vary up to 20 seconds over those 3 positions. All the watch has to do is spend a little bit more time in a position that runs a bit faster, and you get the sort of gain you are seeing.

Since the average daily rate tolerance for this watch is from -1 to +11 seconds per day, you still have a very accurate watch.

Cheers, Al

 

Forgive the newbie question, is it safe to assume this would also apply to the 1861 movement in my 3570.50? Just trying to learn.

 

Same specs yes.

 

Thank you.

 

Thanks Archer, learning more! I have tried to rule out the positional variance by keeping the watch stored the same way overnight, for roughly the same time.

I know my watch runs a little faster during the day, then slows down if I rest it dial up overnight, bringing the accuracy back into line slightly. I have been doing the same since I moved over here but have not seen the same 'slowing down' overnight, which is why I wondered about other factors.

As you say, +4 even for a COSC is pretty good, so I know I'm onto a winner, just wondering of there's anything I could reasonably do to keep it sweet.

Cheers

 

Positional variance is not just something that happens overnight. Unless you move your arm in the exact same way every day, and keep it in the same positions for the same amounts of time, positional variation will come into play. You say you are now in Nevada instead of the UK. Are you now on vacation, or doing different things all day from what you did while in the UK? If so, it could be as simple as that.

 

I'm working, so doing pretty much the same as back in the UK, for the same sort of time periods. It's only really the atmospherics that have changed, which is why I was wondering. Would a single, abrupt shock affect long-term accuracy?

 

love eating popcorn while learning..........

 

vital popcorn could work, too

 

Possibly - the balance on this watch is not free sprung, so there are regulating pins. I often find that watch can have really tight regulators that are hard to move (making them a pain in arse to adjust in small amounts - you overcome the force to get it moving, and then it goes too far...) or they can be loose, making them easy to adjust, but also easily moved with a shock. Then there is the mama bear with the porridge that is just the right temperature, and the friction on the regulator assembly is neither too tight or too loose...

If yours happens to be one that is fairly loose, a sharp bump could have moved it slightly. Less likely IMO is that the balance spring was put slightly out of center by the knock, causing a rate change.

If it bothers you that much, get it regulated, but honestly it's running well...

 

You know you can edit your own posts for spelling, right? Click on OPTIONS... at the bottom right of your post and the first selection from the drop down box should be EDIT.

 

Thank you Archer. I think I'll keep an eye on it for the moment and see if it settles down at all. As I'm away from home, I don't really want to be without my watch for any real period of time and I wouldn't know where to send it out here! Out of interest, how much doe sit typically cost for a regulation, and how long should it take? If it gets worse for any reason I may consider it but I think I'll leave it for now.

 

Al who?

 

I figured that much!

 

In general, there are a lot of factors that can affect how a watch runs....from the state of wind to positional variation to temperature variation....then shocks, magnetism, etc.

In this case, it's likely just positional variation. The Speedmaster Pro is not a COSC watch, so it has very generous running tolerances for accuracy. Since it's not COSC, it is only measured in 3 positions instead of 5 that a COSC would be checked in. Over those 3 positions at full wind, the watch can vary up to 15 seconds. At full wind -24 hours, it can vary up to 20 seconds over those 3 positions. All the watch has to do is spend a little bit more time in a position that runs a bit faster, and you get the sort of gain you are seeing.

Since the average daily rate tolerance for this watch is from -1 to +11 seconds per day, you still have a very accurate watch.

Cheers, Al

Hi Al ,
May I ask ?
Can above apply for 1866 ?

 

Yes.

 

My experience with an 1861 Speedmaster, whacking it against something can indeed change the rate, but it usually returns to normal after a couple of days. My theory is that the end cap jewel doesn't come back to exact center right away, but it eventually will.

Mine also runs +2 as returned from servicing by Omega. The service warranty card says it was set to an average daily rate of about +3.5.

Of course now I haven't worn my Speedmaster since I bought the Watchco Seamaster 300.

Tom