Omega 861 regulation

plttvmt · Jan 12, 2021

Hi all,
I would like to tweak the timing on my Omega 861 movement (Speedy Mk II) to slow it down a bit (gaining ~15 seconds per day), I would like to ask experts here if it is sufficient to move the screw indicated with a blue arrow in the attached photo, and in which direction, clockwise or counterclockwise, or any other useful info/indication to proceed safely and correctly.

Please note that at the moment it is impossible to take to watch to a professional, I am asking this also for personal knowledge, I am perfectly aware of the care and of the caution necessary for proceeding with such actions and of the consequences on my watch of even small errors (I did it on several other watches without harming them), and I also state that I am >18 y.o. 😀

Thank you in advance for any help

jmnav · Jan 12, 2021

The thing to remember is the closer the two "bars", the slower the watch (because the hairspring gets longer). As you see, the screw is an excentrical one that will move the two bars together when screwing counter-clockwise.

plttvmt · Jan 13, 2021

Thank you very much! As from your experience, do you also have any suggestion about the amount of rotation to apply to the screw? E.g., a quarter of counter-clockwise rotation (90°) = about 10 seconds/day slower...? Otherwise I will go with trials and errors, which is of course perfectly fine.

Chewbakkka · Jan 13, 2021

It is very sensitive. I would do it per 5° instead of 90° in one time 😀

plttvmt · Jan 13, 2021

Chewbakkka
It is very sensitive. I would do it per 5° instead of 90° in one time 😀

I think I'll follow your suggestion... 😀 Any other advice?

swish77 · Jan 17, 2021

Any update on this thread? I'm curious if the OP was successful. Thanks.

plttvmt · Jan 18, 2021

Yes! I was waiting a few days to be more sure about the results:

as suggested, I turned the screw counter-clockwise a very few degrees (I would say ~5°, the difference between before and after was almost indistinguishable).

Wearing the watch as I was doing before (~16 hours per day) and let it rest at night on a inclined plane I now reduced the rate from the previous unsatisfactory +15 seconds/day to a stunning +2 seconds/day, which is absolutely perfect for me!

Thank you so much, swish77 and Chewbakkka for your advices.

I have now another question: I decided to regulate the watch myself because I was unsatisfied with the regulation operated by a professional few months ago: his timegrapher was reading +4s/day (photo attached), which would have been absolutely ok with me if true, but then, on the wirst, the reality was those +15s/d.

Do you think that his timegrapher could be not well calibrated? He also regulated a Tissot/Lemania 1873 (same movement as Omega 861), the timegrapher reads +1s/d, but the "real" watch rate is -6s/d.

Any explanation?

Chewbakkka · Jan 18, 2021

Your amplitude is pathetic. If you have this amplitude after a service, you really need a new mainspring and the watchmaker did not a good job. If I see this amplitude before a service, I recommend the client for a new mainspring. With a low amplitude, it's difficult for a watch to keep the correct time. It will vary a lot depending on how wound up your mainspring is.

Amplitudes should be around 250-300° depending on how old the watch is. Some older watches still manage to get around 300° but sometimes, you need to be happy with 250-260° if it's a vintage watch. For a 861 which is a decent movement, I would only be happy in the range 270-300°

amfalconer · Jan 18, 2021

That amplitude seems a bit low, has it been serviced recently?

amfalconer · Jan 18, 2021

Ahh, beaten to it!

onlyomega94 · Jan 18, 2021

plttvmt
Yes! I was waiting a few days to be more sure about the results:

as suggested, I turned the screw counter-clockwise a very few degrees (I would say ~5°, the difference between before and after was almost indistinguishable).

Wearing the watch as I was doing before (~16 hours per day) and let it rest at night on a inclined plane I now reduced the rate from the previous unsatisfactory +15 seconds/day to a stunning +2 seconds/day, which is absolutely perfect for me!

Thank you so much, swish77 and Chewbakkka for your advices.

I have now another question: I decided to regulate the watch myself because I was unsatisfied with the regulation operated by a professional few months ago: his timegrapher was reading +4s/day (photo attached), which would have been absolutely ok with me if true, but then, on the wirst, the reality was those +15s/d.

Do you think that his timegrapher could be not well calibrated? He also regulated a Tissot/Lemania 1873 (same movement as Omega 861), the timegrapher reads +1s/d, but the "real" watch rate is -6s/d.

Any explanation?

Apart from the amplitude it could also be that the watchmaker checked the watch in one position only. When wearing the watch on the wrist it of course moves in several positions which could have an impact on performance.

plttvmt · Jan 18, 2021

Chewbakkka
Your amplitude is pathetic. If you have this amplitude after a service, you really need a new mainspring and the watchmaker did not a good job. If I see this amplitude before a service, I recommend the client for a new mainspring. With a low amplitude, it's difficult for a watch to keep the correct time. It will vary a lot depending on how wound up your mainspring is.

Amplitudes should be around 250-300° depending on how old the watch is. Some older watches still manage to get around 300° but sometimes, you need to be happy with 250-260° if it's a vintage watch. For a 861 which is a decent movement, I would only be happy in the range 270-300°

Argh, I was not aware that 186° was soo low, I know that amplitudes can vary of ~50° so I was assuming that 186° it could be a decent value. Thank you for let me know. Does this mean that I should observe ample variations in the rate (for example in different positions)?

The watch was not serviced but just regulated after restoring water resistance only.

Should I conclude that 215° in the Lemania 1873 is also too low?

Mainsprings are not very expensive, I assume labour costs are...

Thank you again.

Canuck · Jan 18, 2021

The rate shown by a timing machine takes a brief “snapshot” of the rate at that particular moment, extrapolates that forward to predict what the rate would be if the watch stayed at that specific rate for 24-hours. Timing machines are very useful in diagnosing problems in the function of a watch, but when it comes to bringing a watch rate to seconds per day, there is no substitute for regulating the watch based on its rate on the wrist over 24-hours. The rate after 24-hours is a mean average of the slight variations in rate changes during the day. This is less of a factor on highly precise chronometer watches.

plttvmt · Jan 18, 2021

Canuck
The rate shown by a timing machine takes a brief “snapshot” of the rate at that particular moment, extrapolates that forward to predict what the rate would be if the watch stayed at that specific rate for 24-hours. Timing machines are very useful in diagnosing problems in the function of a watch, but when it comes to bringing a watch rate to seconds per day, there is no substitute for regulating the watch based on its rate on the wrist over 24-hours. The rate after 24-hours is a mean average of the slight variations in rate changes during the day. This is less of a factor on highly precise chronometer watches.

I totally agree, but should I assume that there can be such a large difference between the timegrapher (rate: +4s/d) read and the 24-h observation (rate: +15s/d)? Can this difference be due to the low amplitude of my mainspring? Or in general to the fact that it is a vintage watch? Is this difference usually lower in new (high quality) watches?

Thanks again.

Canuck · Jan 18, 2021

Canuck
The rate after 24-hours is a mean average of the slight variations in rate changes during the day.

Please re-read this part of my post.

ChrisN · Jan 18, 2021

Have a look here to understand the timing of watches:
https://omegaforums.net/threads/timing-tolerances-a-guide-to-understand-how-they-work.87293/

The 186 degrees seems too low but, if it were after the watch was fully wound and then rested for 24 hours AND it was a vertical position AND the chronograph was running, it would not be far off for a watch that hasn't been serviced for a while. There is quite a lot to work out here and the best way to start would be to check with the watchmaker what the conditions (and lift angle) are for the test shown. It would be unusual to show such a value when it looks very poor but, people show different things.

Cheers, Chris

plttvmt · Jan 19, 2021

Canuck
Please re-read this part of my post.

Ok got it, so for example if I change the position maybe I'll read +20s/d and in another -1s/d.

I have two questions:

- has anyone ever experimented if there is one single position in which the timegrapher read can be considered closer to the condition of wearing the watch on the wrist?

- can (some types of) timegraphers automatically calculate the average rate after several measures in different positions?

plttvmt · Jan 19, 2021

ChrisN
Have a look here to understand the timing of watches:
https://omegaforums.net/threads/timing-tolerances-a-guide-to-understand-how-they-work.87293/

The 186 degrees seems too low but, if it were after the watch was fully wound and then rested for 24 hours AND it was a vertical position AND the chronograph was running, it would not be far off for a watch that hasn't been serviced for a while. There is quite a lot to work out here and the best way to start would be to check with the watchmaker what the conditions (and lift angle) are for the test shown. It would be unusual to show such a value when it looks very poor but, people show different things.

Cheers, Chris

Thanks a lot, Chris, this is very instructive!

Paolo

amfalconer · Jan 19, 2021

plttvmt
- has anyone ever experimented if there is one single position in which the timegrapher read can be considered closer to the condition of wearing the watch on the wrist?

Have you seen the recent thread 'adjusted for wear'?

I shouldn't begin to worry about regulating that movement further until you can be sure it's healthy

plttvmt · Jan 26, 2021

A short update exactly about the 'adjusted for wear' topic:

I wore the watch for more of one week and checking every morning the deviations, registering a very constant +2s/d.

I left it unworn and standing from Friday evening (~h.22.00) to Sunday afternoon (~h.15.00; total ~41 hours), dial up and fully winding it at morning, room temperature 10-14°C.

In checking the deviation yesterday Monday morning, I found a quite unexpected +45 seconds from the last check (Friday morning), which should account for a shocking +26s/d.

I wore it normally the whole Monday and this Tuesday morning I checked again: back to the above 2s/d.

I really didn't expect such huge difference in wearing or not wearing it, should it be due (partly) to the low amplitude... (and room temperature?)?

Omega 861 regulation

plttvmt

jmnav

plttvmt

Chewbakkka

plttvmt

swish77

plttvmt

Chewbakkka

amfalconer

amfalconer

onlyomega94

plttvmt

Canuck

plttvmt

Canuck

ChrisN

plttvmt

plttvmt

amfalconer

plttvmt

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