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Discussion Starter · #1 ·
Hello,

I am wondering if all mechanical chronographs are subject to possible chrono hour creep? Is this a flaw in there design? Do alternate designs prevent it ie like vertical coupling vs horizontal?

Are there certain watches that do not experience it? Even the mighty zenith seems subject to it.

Note: chrono hour creep = when the chronographs hour tracker no longer matches the minute tracker. see attached photo. it occurs when the chrono is started and stopped many times over the course of hours without resetting the chronograph. In the photo below, the minutes hand is at 0 min. this means the hour should be either on the hour, or half way between the hours. here, the hour should be at exactly 8. but instead it is at 7.75 hours. that is the problem.

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Thank you,
Markus
 

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I've read it somewhere awhile that it is a fixable issue. I will come back to this thread if I can find it.

None of my Zenith watches has this issue. I do recall seeing one of my vintage chronographs with Valjoux 72 has this hour hand creep issue.
 

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I have that issue with my Breitling (7750 base), even to the extent that the hour hand moves farther than the minutes should allow when clocking long trips (6 hour flights, etc). It's annoying and once I have it serviced next, I will make sure it doesn't do that anymore...
 

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Discussion Starter · #4 ·
Thanks for the responses. My zenith is brand new so that’s why I am doubting it’s a quality flaw, but rather a design flaw/weakness.


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Discussion Starter · #6 ·
Your watch is brand new and under warranty, I would exchange it for another watch ASAP.
That is a good idea and I will likely do that.

However, I am wondering how the watches are designed and what causes this?

I have experienced it with so many watches I am starting to feel like it is more of a design issue, then a quality issue.

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Discussion Starter · #8 ·
Also note, it only occurs if I start and stop the chrono often over long periods without resetting. Otherwise if I just start the chrono and let it run it tracks perfectly


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Note: chrono hour creep = when the chronographs hour tracker no longer matches the minute tracker. see attached photo. it occurs when the chrono is started and stopped many times over the course of hours without resetting the chronograph.
What you are experiencing is different from what the typical hour recorder creep is. That term is commonly used to describe an hour recorder that moves even when the chronograph is not running. But the problem you are having and that one are related to a degree, and it is something that is influenced by the design of the movement. In watches where this happens, the hour recorder is driven directly off the mainspring barrel, and is not directly connected to the train that is driving the chronograph seconds and minute recording hands.

So here is an Omega Cal. 321 and this is the train side of the movement:



The red arrow was put there for another reason, but if you look just below and to the right of that arrow there is a large gold coloured gear, and this drives a smaller gear that is on the coupling yoke. This coupling yoke is what moves in and out to engage with the wheel that has the seconds recording hand on it (the one in the very center of the movement), and that wheel has a finger on it that trips the minute counter (the one at 9 o'clock in this photo). So these three wheels are in a line across the movement, with the seconds and minutes are driven off this one large brass gear on the left side of that line, and that wheel is pressed onto an extended post on the fourth wheel that is inside the movement and you can't see - the fourth wheel is the wheel that the constant seconds hand runs on.

So how is the hour counter driven? Not from any of this mechanism - it's on the dial side of the watch, and here I've removed a bridge to show the parts involved:



A - friction spring
B - pinion
C - hour recording wheel
D - hour hammer

The hour recording wheel is what the hour recording hand mounts to, and this is the hand that is often creeping or not keeping exact pace with the minute recorder. It is driven by a pinion that is connected to the mainspring barrel by a friction spring. So when the watch is running, the barrel is turning and the pinion is being driven, and it's trying to turn the hour recording wheel. There is a brake (not shown) that stops the wheel from turning when the chronograph is reset, and since that pinion is only coupled to the mainspring barrel by that friction spring, it can slip on the barrel arbor when the chronograph is not running. What most people call hour recorder creep is when either the brake is not providing enough friction to stop the hour recording wheel from turning, or the friction spring is providing too much friction and too much drive to the hour recording wheel - usually due to lubrication getting sticky.

So the main take away here is that the hour recorder is driven off a separate part of the movement, so it is "prone" to not being 100% in sync for various reasons. I can't comment on what is causing the issue with the Zenith, but the configuration there is similar, but not the same as the Omega 321 I've shown. I don't service a lot of El Primeros, but I managed to dig up a photo of a Cal. 3019 from a while back, and this is the dial side with the red arrow pointing to the hour recording wheel, and you can see the friction spring arrangement on top of it:



I'm guessing now, but with the specific watch you are asking about I would say that perhaps the drive of the hour recorder is not strong enough, so when you are starting/stopping the chronograph the hour recorder is not starting back up right away, leading to a lag over time.

Other chronographs use the same system, like the ubiquitous ETA 7750:



Again this is the dial side, showing the parts of the hour recorder mechanism. However here the pinion on the barrel is rigidly attached to the barrel:



Here is where the pinion is when the barrel is installed:



Left arrow shows where the hour recording wheel goes, and the right arrow is the end of the barrel arbor where the pinion is:



So there is still a friction clutch in the system, but it's built into the hour recording wheel - the triangular part runs on a stepped surface of the wheel - this is where it slips when the chronograph is not running:



Note that this friction clutch and the one on the Cal. 321 above also allow the hour recorder to be reset without disconnecting the hour recording wheel from the pinion that drives it.

All of these problems are fixable, and honestly most times when I get a chronograph in with a problem related to the hour recorder, just doing a regular service solves it, and no additional parts are adjustments are needed. Sometimes I might have to adjust the brake, or replace a friction spring, but most of the time just proper cleaning and lubrication are all that's required.

Regarding watches that don't use this system of driving the hour recorder from the barrel, they are certainly out there. Off the top of my head the first that comes to mind are the F. Piguet based chronographs (including those under the Omega 3303/3313 series) and of course the Omega 9300 series watches. There are probably others out there as well but I've already spent some time on this post so I'll leave that research to you to do.

Cheers, Al
 

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My 2 chronos - 7750 and L688.2 - do the same thing (except the hour hand creeps ahead - there is an old thread about that, in the watchmaking subforum).

The 7750 - that creeps more - was recently serviced (not fully - was sent to the AD to fix a chrono-hand-not-resetting-correctly + they fixed the creep, too. But not full service, as the charge was minimal) + the situation improved A LOT (ie I would not notice a creep before several hours of running); however, after a few months... back to where it was :-(

...recommend buying a Lange chrono + sparing yourself the aggravation :) (does anybody know if the vaunted Daytona does it, too?).


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Discussion Starter · #15 ·
Wow. Al, that response was so informative!! I am very appreciative!!!

I full understand now. I am hoping this post helps others understand watch movements better.


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Discussion Starter · #16 ·
I wonder if the Rolex Daytona 4130 does this.
Or the Breitling B01, or even the Seiko 8r48. So much research to do now so little time!

Watches are made to tell the time... all they do is take up my time :p


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