Watch accuracy and performance

TechFounder · May 23, 2020

I always thought that the performance of a watch in terms of its accuracy should be fairly consistent between certain percentages of power in its reserve. So, say, between 80% and 20%, the accuracy should be within some specified parameters after service or when purchased new. Am I wrong about that? Also, is that the correct range or is it even better, 90% to 10%?

Second question. When you own an automatic and you wear it during the day for 12 hours doing various activities, shouldn't those activities be enough to wind the movement 90%+ to full reserve power?

I just had a watch serviced and it's failing on both counts and I'm wondering if I should send it back for a redo?

Canuck · May 23, 2020

You’ll need to tell us a lot more about the subject watch before we can meaningfully suggest whether it should be expected to be any better with respect to the rate at fully wound, and the rate after say 24 hours.

When a watch is adjusted At the factory for isochronism, and is otherwise in good condition and competently adjusted, the rate after 24 hours should be quite close to the rate when fully wound. Not all watches are designed to exhibit stability of rate when fully wound, and after a 24 hour run. As to how fully wound the watch should be after being worn for a day? Again, we need to know more about the watch. Maker? Model? Age? Movement calibre? Error in rate after a day of wear? How long it actually runs after a day of wear? Anything else specific about it that may help us shed some light on your questions.

Some of my older self winders (bumper automatics) function more predictably when I wind them fully by hand when I put them on to wear them.

amcclell · May 23, 2020

There are way to many variables to get accurate answers to the questions you are asking. If accuracy is a priority, you are better to use your cell phone or buy a cheap quartz watch. I have some watches that very slightly between 20 and 80%, say 4-6 seconds per day and some others will 15-20 seconds a day between these same state of wind conditions. Even the predominant positions that the watches are in will effect their accuracy. As far as maintaining wind goes, some of my auto wind watches have extremely efficient winding mechanisms and some not so much. My Zenith El Primeros are amazing and my two Omega Seamasters (1120 and 562) are also pretty good if I wear them 12 hours a day with normal activity. I have a Felsa 4009 in a late-60's dive watch that was serviced just this year and it runs down over the course of 4-5 days of normal wear. There is nothing is wrong with it I just need to give it a bit of a wind every 3-4 days and I am good. I took it back to my watchmaker who confirmed that everything was moving freely.

I sold a Hamilton micro-rotor piece to a friend, a few years back and it was much the same. The auto wind worked but just not efficiently if you were not moving vigorously. As far as accuracy goes, some of my watches can go a month before I need to reset the time and others, I reset once a week. The ones that I wear regularly get serviced every 4-7 years and they are all different. Getting to know them, including their idiosyncrasies is part of the experience and enjoyment.

kkt · May 23, 2020

TechFounder
I always thought that the performance of a watch in terms of its accuracy should be fairly consistent between certain percentages of power in its reserve. So, say, between 80% and 20%, the accuracy should be within some specified parameters after service or when purchased new. Am I wrong about that? Also, is that the correct range or is it even better, 90% to 10%?

Second question. When you own an automatic and you wear it during the day for 12 hours doing various activities, shouldn't those activities be enough to wind the movement 90%+ to full reserve power?

I just had a watch serviced and it's failing on both counts and I'm wondering if I should send it back for a redo?

Tell a lot more about it. What's the watch? What's the specification accuracy? What are you observing, and how are you observing it? How are you determining what the power reserve is?

TechFounder · May 23, 2020

So, it's a BlancPain Aqualung smalldate. It has the 1151 movement which is rated at 100 hours reserve. Just had it factory serviced last year which they promised to return the movement to like new condition. They said that it should be +5 to -2 per day. It started out being about +7 sec when full wound, and about +5 sec from about 80% to 40% but after a year the performance has deteriorated tremendously. It's now +-2 sec when 100% - 60% if face up or on wrist but if left on the dresser with crown up, it loses 5 sec per day. Between 40% and 10% is when it really starts to deteriorate. At 40% - 20% it loses about 7 sec a day and < 20% it loses 30 sec a day.

I don't remember previous mechanical watches with such poor performance numbers. Perhaps I wasn't paying as much attention in the past but this leads me to think that there may be something wrong with the spring which is the source of power? It seems like it's not releasing consistent power through its power range? It's double barreled so it should be like this? Do they normally replace springs during complete overhauls?

TechFounder · May 23, 2020

I also just sent my 1962 Seamaster to Bienne for a complete overhaul and will get it back soon. I hope it has much better performance numbers than this. Anyway, I will compare the performance once I get it back. Although, they said that with calibre 552. Their tolerances are between -1/+16 seconds a day.

Canuck · May 23, 2020

You are clearly not happy with the way it is performing. I suggest you return it to whoever it was that serviced it, and have them go through it again. As to power reserve, this movement has an auto wind system in which the rotor winds in one direction only. If you use a watch winder and if the winder is turning your watch in the wrong direction, no winding is taking place. That could affect both the rate and the reserve. Why not wind it fully, manually, once each week, and see if that changes its performance.

TechFounder · May 24, 2020

Canuck
You are clearly not happy with the way it is performing. I suggest you return it to whoever it was that serviced it, and have them go through it again. As to power reserve, this movement has an auto wind system in which the rotor winds in one direction only. If you use a watch winder and if the winder is turning your watch in the wrong direction, no winding is taking place. That could affect both the rate and the reserve. Why not wind it fully, manually, once each week, and see if that changes its performance.

The watch was serviced by BlancPain Switzerland so I would expect it to be done correctly the first time? But before I send it back in I thought that I ask some of the forum members so I at least would know the truth about what the correct operating specs are. I'm sure they will give me all sorts of push back about how that's normal but I don't believe so.

I would think that with a 100 hour reserve movement, you would never need to manually wind it if you wear it daily. Even if you set it down over a weekend. Manually winding would sort of defeat the purpose of having a reserve of 100 hours?

I understand that it has a one direction rotor winding system, but what's the expectation for these system? That they only wind to 60-70% every 12 hours of wear or do you expect them to maintain close to 100% reserve when worn daily for 12 hours at a time? No one seems to be able to give me a straight answer. Isn't this one of the specs you use to determine whether or not your movement is performant or in need of service?

amcclell · May 24, 2020

I would run this question by Archer.

TechFounder · May 24, 2020

Hey @Archer, any helpful insight would be appreciated!

Archer · May 24, 2020

TechFounder
So, it's a BlancPain Aqualung smalldate. It has the 1151 movement which is rated at 100 hours reserve. Just had it factory serviced last year which they promised to return the movement to like new condition. They said that it should be +5 to -2 per day. It started out being about +7 sec when full wound, and about +5 sec from about 80% to 40% but after a year the performance has deteriorated tremendously. It's now +-2 sec when 100% - 60% if face up or on wrist but if left on the dresser with crown up, it loses 5 sec per day. Between 40% and 10% is when it really starts to deteriorate. At 40% - 20% it loses about 7 sec a day and < 20% it loses 30 sec a day.

First question is, how are you determining that the watch is 80%, 40%, or whatever % wound?

Second question is, do you have a timing machine?

Canuck · May 24, 2020

My suggestion re: beginning a test period by manually winding it fully was predicated on allowing the watch to “top up” the power reserve each day as you wear it. This, rather than putting it on run down, and hoping it will eventually be able to achieve a fully wound state over time, with irregular wearing patterns. How old is the watch, and what was it’s behaviour pattern before you sent it for service? Had the performance deteriorated which precipitated your having sent it for service?

Compare your watch which has a 100-hour reserve, with a watch with, say, a 52-hour reserve. It will take longer for your watch to “fill the tank” than it would take for a watch with a 52-hour reserve to fill the tank, if you are relying on time on the wrist alone, to fully wind the watch. Especially considering that your watch is only winding HALF the time that the rotor is moving! Only trying to help. But I suspect that if you experiment a bit, you might be able to resolve these issues without sending it back to Blancpain. These issues may well still exist even if you do send it back to Blanpain.

TechFounder · May 24, 2020

Archer
First question is, how are you determining that the watch is 80%, 40%, or whatever % wound?

Second question is, do you have a timing machine?

I did it the manual way which is I would wind the watch completely and then time it each day until it stops. Since I don't have any devices to time it, I had to run this multiple times using different parameters each time such as timing it face up or crown up.

For the reserve test I wind the watch completely, then wear it for about a week, 12 hours a day, and then wait to see how long it took for it to stop.

TechFounder · May 24, 2020

Canuck
My suggestion re: beginning a test period by manually winding it fully was predicated on allowing the watch to “top up” the power reserve each day as you wear it. This, rather than putting it on run down, and hoping it will eventually be able to achieve a fully wound state over time, with irregular wearing patterns. How old is the watch, and what was it’s behaviour pattern before you sent it for service? Had the performance deteriorated which precipitated your having sent it for service?

Compare your watch which has a 100-hour reserve, with a watch with, say, a 52-hour reserve. It will take longer for your watch to “fill the tank” than it would take for a watch with a 52-hour reserve to fill the tank, if you are relying on time on the wrist alone, to fully wind the watch. Especially considering that your watch is only winding HALF the time that the rotor is moving! Only trying to help. But I suspect that if you experiment a bit, you might be able to resolve these issues without sending it back to Blancpain. These issues may well still exist even if you do send it back to Blanpain.

What i noticed was that at around 50-60% reserve the rotor would become more difficult to rotate in the direction that it needs to wind the watch. Since it has a display back I can easily manipulate the watch in order to see how it behaves from movements. I would expect that it becomes a little bit difficult but not to the point where it looks now. I would either have to slowly rotate the watch with the rotor pointing to the ground or it won't wind. Normally flicking the watch would rotate it but not when it's around 50-60%. I'm wondering if there might something wrong with the spring since that's not normally replaced during service? I'm guessing that would cause the rotor to behave this way?

Canuck · May 24, 2020

I would suggest that the mainspring would have been replaced during service. This makes better sense than to remove the mainspring during service, cleaning, rinsing, lubricating, and re-inserting the spring during re-assembly. Simply apply braking grease to the newly cleaned mainspring barrel, lay a new, freshly lubed mainspring in its capture ring over the barrel, right side up, then press it in. Job done.

How it is that you are able to judge that your watch is about 60% wound as you observe the rotor, remains a mystery to me. If the rotor appears to you to be sluggish as you rotate the watch Slowly, off the wrist, bear in mind that the more vigorous motions of your watch during wear would likely overcome any perceived sluggishness of the rotor.

Archer · May 24, 2020

TechFounder
I did it the manual way which is I would wind the watch completely and then time it each day until it stops. Since I don't have any devices to time it, I had to run this multiple times using different parameters each time such as timing it face up or crown up.

For the reserve test I wind the watch completely, then wear it for about a week, 12 hours a day, and then wait to see how long it took for it to stop.

Let's look at timing first. Fully wind the watch using the crown, set the time and note it to a known good time source (time.gov or something similar) lay it dial up, wait 24 hours, and note the gain or loss. Repeat this test for dial down, crown left, crown right, crown up, and crown down. Fully wind the watch before each 24 hour period.

Let us know the results of that first, then we can move on.

TechFounder · May 24, 2020

Canuck
I would suggest that the mainspring would have been replaced during service. This makes better sense than to remove the mainspring during service, cleaning, rinsing, lubricating, and re-inserting the spring during re-assembly. Simply apply braking grease to the newly cleaned mainspring barrel, lay a new, freshly lubed mainspring in its capture ring over the barrel, right side up, then press it in. Job done.

How it is that you are able to judge that your watch is about 60% wound as you observe the rotor, remains a mystery to me. If the rotor appears to you to be sluggish as you rotate the watch Slowly, off the wrist, bear in mind that the more vigorous motions of your watch during wear would likely overcome any perceived sluggishness of the rotor.

You can judge by fully winding the watch. Record each day the time difference to an atomic clock. Each day would correspond to about 25% of reserve since we're talking about a 100 hour reserve.

TechFounder · May 24, 2020

Archer
Let's look at timing first. Fully wind the watch using the crown, set the time and note it to a known good time source (time.gov or something similar) lay it dial up, wait 24 hours, and note the gain or loss. Repeat this test for dial down, crown left, crown right, crown up, and crown down. Fully wind the watch before each 24 hour period.

Let us know the results of that first, then we can move on.

So, first of all, attached is the result of a fully wound watch I had the BlancPain boutique run a couple of months ago before the lockdown. Is there a reason why you would need to know all of the positions rather just a couple? Let's say if it's already -7 sec/day face up when it's around 40% reserve does it matter what the other position shows since face up is usually one of the faster positions?

Also, isn't the accuracy suppose to stay relatively stable in each position, say, face up, through the entire range of power reserve, say, 80% - 20%? If I'm getting large variances, doesn't that mean I need it to be re-serviced? What I'm really concerned about is the tail end of the reserves. It's losing around 30 seconds towards the last day of reserves. That can't be normal can it?

Canuck · May 24, 2020

Face up usually one of the faster positions? Where’d you pick that up? Maybe so with your particular watch, but not with every watch.

Archer · May 24, 2020

TechFounder
So, first of all, attached is the result of a fully wound watch I had the BlancPain boutique run a couple of months ago before the lockdown. Is there a reason why you would need to know all of the positions rather just a couple? Let's say if it's already -7 sec/day face up when it's around 40% reserve does it matter what the other position shows since face up is usually one of the faster positions?

Also, isn't the accuracy suppose to stay relatively stable in each position, say, face up, through the entire range of power reserve, say, 80% - 20%? If I'm getting large variances, doesn't that mean I need it to be re-serviced? What I'm really concerned about is the tail end of the reserves. It's losing around 30 seconds towards the last day of reserves. That can't be normal can it?

I'm just trying to help, but if you don't want to do the tests that's fine.

Watch accuracy and performance

TechFounder

Canuck

amcclell

kkt

TechFounder

TechFounder

Canuck

TechFounder

amcclell

TechFounder

Archer

Canuck

TechFounder

TechFounder

Canuck

Archer

TechFounder

TechFounder

Canuck

Archer

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