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Expected Precision of Omega Caliber 420 (1950s) After Recent Service

Art.
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Hi everyone,

I have a vintage Omega with the manual-wind Caliber 420 from the 1950s. It was serviced a few months ago, and I’m wondering what kind of accuracy I should expect at this point. I understand that factors like age and wear can affect it, but assuming it’s in good condition, what daily time deviation is typical for this movement a few months after service?

Thanks in advance for any insights!
 
impaw
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Hi
May I ask how many seconds you are off at this point?
I have a 1952 Seamaster that currently is about 5seconds too fast, 4 months since last service.
Dont know if this is normal, but I am very pleased with it.
 
Art.
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At this point, my watch is off by a few minutes, though I haven’t measured the exact number of seconds per day. I would like to know where to set the bar when it comes back from service. Your Seamaster seems to be doing great if it’s only 5 seconds fast after 4 months since its last service—that’s quite impressive!
 
impaw
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Art. Art.
At this point, my watch is off by a few minutes, though I haven’t measured the exact number of seconds per day. I would like to know where to set the bar when it comes back from service. Your Seamaster seems to be doing great if it’s only 5 seconds fast after 4 months since its last service—that’s quite impressive!
Yes, I am very happy with it😀

I am no expert but I think you can expect your watch to be within second, not minutes off, per day.

will do an updated check now, to see if ,mine is still within the 5 secs I bragged about 😁
 
Dan S
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The timekeeping needs to be expressed as time per day. Measure that, and let us know. Suggesting that it is several minutes off, cumulatively, over an indefinite number of days, is not helpful. Even when new, a non-chronometer movement was probably only specified to be within something like 10-15 seconds per day.

I assume that @impaw is saying that his watch is keeping time to within 5s/day, which is excellent. If it is truly only 5s off cumulatively over several months, that is beyond extraordinary, and just good luck.
Edited:
 
Art.
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Specifically, it gained about 4 minutes over a 4-hour span. Can I expect this rate to be linear? If so, would it result in a 24-minute gain over the course of a day?
 
Dan S
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Did you wind it completely? 4 minutes over 4 hours is not good. If it was fully wound, it might be magnetized or there could be some oil in the hairspring.
 
Art.
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I did wind it completely. You’re right, it’s not looking good at all. But if the watch is serviced again, what kind of accuracy (in seconds per day) should I expect?
 
impaw
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I have not worn it every day the last couple of months, and only done a handful of measurements, but they have been very good🥳
Watch this space tomorrow for and updated measurement😀

@Art. Do you have a photo of your watch, always interesting to see the watch being discussed
 
Dan S
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If it was serviced, it should not need to be serviced again. Just have the watchmaker take a look and see why it's running so crazy fast. Most likely it will be within 30s/day, and with some adjustment, 15s/day.
 
impaw
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impaw impaw
I have not worn it every day the last couple of months, and only done a handful of measurements, but they have been very good🥳
Watch this space tomorrow for and updated measurement😀

@Art. Do you have a photo of your watch, always interesting to see the watch being discussed

For those holding your breath:
Currently about a second off, after almost 12 hours on the bedside table. I’ll report back in 12 more hours👍
Caliper 354 btw, bumper automatic

IMG_2126.webp
 
JwRosenthal
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impaw impaw
For those holding your breath:
Currently about a second off, after almost 12 hours on the bedside table. I’ll report back in 12 more hours👍
Caliper 354 btw, bumper automatic

IMG_2126.webp
I had a watch that had been serviced which kept excellent time on the dresser- not so much when you wore it. I tried it in a few different positions on the dresser and found it ran great on its back, and right side and poorly on its face and left side. Turns out it was a worn balance staff- watchmaker hadn’t checked it for wear. He admitted it was his fault, and replace the balance and the jeweled pivot it sat in which was also worn (I offered to pay for the part as it wasn’t cheap and he covered the labor) and it kept time in any position within 7-10 seconds a day thereafter.
Shit happens.
 
Art.
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impaw impaw
I have not worn it every day the last couple of months, and only done a handful of measurements, but they have been very good🥳
Watch this space tomorrow for and updated measurement😀

@Art. Do you have a photo of your watch, always interesting to see the watch being discussed
It is a recent purchase, and I plan to post some pictures on the forum. I’d also like to inquire about its model and verify whether the papers I received correspond to the watch.
 
Donn Chambers
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Art. Art.
It is a recent purchase, and I plan to post some pictures on the forum. I’d also like to inquire about its model and verify whether the papers I received correspond to the watch.
Since it is a recent purchase, did you have it serviced by your own watchmaker, or was it sold as “serviced?” Because those are two different things, and I wouldn’t trust the seller’s description of a service.
 
Dan S
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Art. Art.
It is a recent purchase, and I plan to post some pictures on the forum. I’d also like to inquire about its model and verify whether the papers I received correspond to the watch.
You will need to compare the serial numbers on the paper and watch, so please post photos of the movement.
 
Art.
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Donn Chambers Donn Chambers
Since it is a recent purchase, did you have it serviced by your own watchmaker, or was it sold as “serviced?” Because those are two different things, and I wouldn’t trust the seller’s description of a service.
The watch was sold as recently serviced, and I noticed the watchmaker's mark on the back of the case dated 2024. The movement looked perfect, no signs of oxidation at all. So, I was pretty shocked when I got home and saw the time drift. I've already reached out to the dealer, and they've invited me to bring it in for a check-up. I'll keep you updated.
 
Art.
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Dan S Dan S
You will need to compare the serial numbers on the paper and watch, so please post photos of the movement.
I might create a new thread for that one though!
 
Art.
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impaw impaw
For those holding your breath:
Currently about a second off, after almost 12 hours on the bedside table. I’ll report back in 12 more hours👍
Caliper 354 btw, bumper automatic

IMG_2126.webp
That's so awesome! What nice timepiece. Congratulations!!!
 
Art.
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JwRosenthal JwRosenthal
I had a watch that had been serviced which kept excellent time on the dresser- not so much when you wore it. I tried it in a few different positions on the dresser and found it ran great on its back, and right side and poorly on its face and left side. Turns out it was a worn balance staff- watchmaker hadn’t checked it for wear. He admitted it was his fault, and replace the balance and the jeweled pivot it sat in which was also worn (I offered to pay for the part as it wasn’t cheap and he covered the labor) and it kept time in any position within 7-10 seconds a day thereafter.
Shit happens.
Mine was way off even just sitting on the dresser. I haven’t even tried wearing it yet since it clearly needs servicing.
 
gbesq
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I’ve owned several Omegas with the caliber 420 movement. Properly serviced and regulated a caliber 420 can easily keep time at +/- 10
SPD and probably better.
 
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