When I look at the watch movements of my vintage Omegas I can see the Omega symbol, however in two cases there is a number 1 inside the Omega symbol and I wondered if anybody can kindly explain the significance of this number?

In the first instance I have found it on a Cal 561 Constellation and in the second on a Cal 562 Seamaster. I would be greatly appreciative if somebody can enlighten me on the purpose of this number.

 

There are posts on this topic
Our expert watchmakers tell us it is something to do with the height of the movement or to the hands ( or something like that)
I'm sure someone will chip in with the accurate answer
Calling @ Archer

 

It's a prototype.

 

I found a page on the Constellation blog with a link to a PDF giving a full explanation http://omega-constellation-collectors.blogspot.co.uk/2010/11/number-1-within-omega-symbol-on.html

Apparently the number 1 denotes an upgrade on an original design.

 

I think we need some clarity on this little number 1
Desmond says it was a sign of a modification to a movement but Archer said he had some different info ( from Omega)

 

I have confirmed with Omega that the number inside the Omega symbol relates to hand or "dialing" heights. It's not related to calendar upgrades or anything of that sort as has been proposed by others.

Cheers, Al

 

Many thanks for this information, it is appreciated. I have no clear idea as to what "Hand or dialling height" means, but the number inside the Omega symbol is now no longer a mystery that I was finding impossible to solve.

 

thanks Al

 

Watch movements are made to accommodate different overall height dials essentially. If you have a flat dial with painted markers, the posts that the hands mount to don't have to be very long so that all the hands can fit on them and clear the dial and each other.

If you have a domed dial, a thicker dial, or a dial with applied markers (or a combination of those) the overall dial height is taller, so the posts that the hands mount to all need to be longer. Of course Omega is not the only brand to do this.

Have a look at this ETA 2892A2 technical guide, and scroll down to the last page.

http://www.phfactor.net/wtf/ETA/14_ETA2892A2.pdf

On that page you will see a cross section of the center of the movement, showing the cannon pinion, hour wheel, and seconds wheel (the three parts that the 3 hands mount to). In the table below you will see various heights (lengths) for all these parts, so for example dimension C is the overall length of the seconds wheel, which can be anywhere from 4.36 mm to 6.36 mm in length, and all of that extra length is on the dial side of the movement. The shorter versions would be used for thinner or flatter dials, and the longer for thicker dials.

It's not uncommon for a movement, say the Cal. 1120, to have 4 different hand heights in order to accommodate different dials. This is why for example doing some popular mods can be tricky, like the "non-AC dial mod" that uses the dial with applied markers from the non-America's Cup SMP on another model. That dial has applied markers and requires much taller posts, so depending on what watch you start with and how short the posts are for that model, it can make doing this mod very difficult since you don't have enough space on the posts for all the hands to fit on.

This is one reason why Omega discourages these types of modifications, because most people don't understand that every Cal. 1120 is not exactly the same design, and if you don't know what you are doing you will end up with a hacked up mess where someone had to bend the hands to get them to clear...not exactly professional work to say the least.

Cheers, Al

 

I sure went down the rabbit hole with that link https://www.phfactor.net/wtf/ which refered to the 2892 PDF. What a treasure trove of technical data sheets. I spent the better part of the morning cross referencing these links. This is why forums like this are so useful.


-j

 

Yes, thank you so much for your willingness to share your info with us.