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Any idea what this "O" means on the rotor ?

RoadRunner73
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I'm offered a nice looking SS 168.005 dating 1969 with a 564 Cal. inside : and I recently realized that the rotors bears an "0" or "O" just underneath "Watch" : then I went on searching, and I found quite a few, but it seems only Cal. 564 have it : any idea what this can mean ? additional proof for a 564 ?

Certainly several OF Members will have the answer : many thanks in anticipation !

upload_2023-4-12_23-19-8.png
 
Peemacgee
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It signifies a replacement part.

Can we see other pics of the watch?
How do you know it dates to ‘69?
 
Peemacgee
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The watch also has what looks to be an incorrect replacement crown.
 
Dan S
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I have also read that the "O" indicates a replacement rotor, and I tend to believe it. But it's also interesting that almost all 564 movements do seem to have a replacement rotor.
 
RoadRunner73
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Dan S Dan S
I have also read that the "O" indicates a replacement rotor, and I tend to believe it. But it's also interesting that almost all 564 movements do seem to have a replacement rotor.

Well this is exactly the point ! I first suspected it to be a replacement rotor, but it took me 10 minutes to check on C24, and find more than 10 Connies with Cal 564 which all exhibit this "O" on the rotor, hence my question; and so far, I cannot recall having seeing any other movement than 564 housing this mark on their rotor... but again, I'm a newbie on Connies, so I thought I'd rather ask the experts.
 
RoadRunner73
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Peemacgee Peemacgee
The watch also has what looks to be an incorrect replacement crown.

Also my opinion, but I will probably not buy this one : the hours markers are painted, no Onyx inserts, and to me the Genta design requires a Dog Leg / Pie Pan to bear Onyx inserts, so I'm gonna keep hunting.
Having said that, a decagonal crown is not ideal for a date dial unless it has the quick set 564 : far too tricky to adjust the date with a crown which is a pain to grasp : so my current inclination is to restrict the lovely decagonal crown to no-date models.
 
Peemacgee
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Dan S Dan S
I have also read that the "O" indicates a replacement rotor, and I tend to believe it. But it's also interesting that almost all 564 movements do seem to have a replacement rotor.

I'm pretty sure that it was @Archer who suggested that the 'O' denoted a replacement rotor.

I've just checked and of the handful of 564s, that I have pictures of, they all have the 'O' on the rotor but the 551 and 561 don't.
However, they all have historical service marks so no smoking gun there.
If it is conclusively a sign of a replacement rotor, then it could be that replacing the rotor was a standard service action for a cal564
It also may be a factor that the O only appeared on the replacement rotors post mid-60s, so it would make sense that more 564s would show Os

A quick google reveals just one non-O rotor, which whilst it looks like it belongs to the watch may itself be a replacement.
But another quick google of 561s and 551s also reveals o-marked rotors

IMG_7350.jpg images-6.jpeg Screenshot 2023-04-13 at 09.58.19.png
 
dsio
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RoadRunner73 RoadRunner73
Also my opinion, but I will probably not buy this one : the hours markers are painted, no Onyx inserts, and to me the Genta design requires a Dog Leg / Pie Pan to bear Onyx inserts, so I'm gonna keep hunting.
Having said that, a decagonal crown is not ideal for a date dial unless it has the quick set 564 : far too tricky to adjust the date with a crown which is a pain to grasp : so my current inclination is to restrict the lovely decagonal crown to no-date models.
+1 I hate that crown. Much prefer the Seamaster Deville style of loosely knurled crown even though it’s wrong for actual wearing.
 
Peemacgee
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RoadRunner73 RoadRunner73
Also my opinion, but I will probably not buy this one : the hours markers are painted, no Onyx inserts, and to me the Genta design requires a Dog Leg / Pie Pan to bear Onyx inserts, so I'm gonna keep hunting.
Having said that, a decagonal crown is not ideal for a date dial unless it has the quick set 564 : far too tricky to adjust the date with a crown which is a pain to grasp : so my current inclination is to restrict the lovely decagonal crown to no-date models.

Agreed that onyx inserts are much nicer than painted inserts.

As I've mentioned before, the crown is fine for changing the date, it's winding that is a PITA but even that really isn't so bad with an automatic.
 
Davidt
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I’ve seen several ‘O’ rotors on non 564’s. They also seem more basic and utilitarian that the normal rotors, which given the direction Omega went with the cal 10xx series, adds weight to them being replacements.
 
RoadRunner73
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Clear ! I'm not bothered by the manipulation of a 10sided crown on an automatic, except for the date change, unless it has a quick set.

With regards to the painted inserts, the dial looks "flat" as compared to Onyx inserts which add volume and are so much more classy !
 
Rudi99
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Summoning @kaplan to join the discussion. If somebody knows their 564, it is him.

I will add I have always seen that O on 564s, specially on C-Shape Connies.
 
Peemacgee
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Davidt Davidt
I’ve seen several ‘O’ rotors on non 564’s. They also seem more basic and utilitarian that the normal rotors, which given the direction Omega went with the cal 10xx series, adds weight to them being replacements.

To be fair, the style of the rotors on late 60s Constellations were pretty basic -like the one on the OPs pic

BA9480EE-3210-4A14-8DDD-D52555CF62CC.jpeg
 
RoadRunner73
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Comparing them visually, some have a rounded edged circumference around the pinion, and some show 2 somewhat sharp corners, whether with or without "O" : so it seems there are at least 4 different shapes, not knowing whether this has an effect on the dynamics of the rotor. Has anybody ever compared weight and thickness of these various rotors ?
 
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