19 ligne Omega

[StuartBaker104]

I rarely work on pocket watches, but fell in love with the hands on this, and got it quite cheaply.  I have seen a couple of other pictures of 19 ligne omega movements with this different bridge design, but no discussion of why, or which variant. I haven't included pictures of the dial side, but it looks just like other 19s.

I need a new mainspring, but the GR catalogue lists many spring types for the Omega 19; none of which quite lines up with what I found fitted. For a start the barrel ID is 16.5mm which doesn't appear on any of the options.

The old spring just had a standard riveted hook bridle, but the barrel has slots which look like they would take a "DBH" bridle.  I've never bought one of those, but it strikes me that the distance between the hook end and the T piece must be exact for it it fit correctly.

The old spring is 0.19mm thick and 2.6 high. The barrel is 16.5 ID & 3.2 deep, and the barrel arbour 5.3 OD.  Theory says the old spring is the right height and thickness. I haven't tried to measure the length, but theory says this should be around 500mm.

There is a letter M stamped on my barrel bridge.  The catalogue lists a 19M with 2.6 x 0.2 x 560 x 17.5 and DBH bridle.  Height and width are good, but the barrel diameter and length are too big!

I will probably just get the nearest size standard hook spring I can find, but if anyone knows more that would be interesting...
 

[StuartBaker104]

A day older and (just) a little wiser.  Omega sold movements into the US market under the brand "Regina", these shared common parts with their other movements but had different bridge designs, it appears they also sometimes sold these movements under the Omega brand just to confuse the unwary.  This doesn't help me much, but for those who speak French, here is a very similar example and some other wonderful information (if you don't speak French, at least look at the table of hand styles in the second link!)

http://forumamontres.forumactif.com/t17823-regina-c-est-beau-c-est-tres-beau?highlight=Regina

https://sites.google.com/site/hourconquest/oomega

Cousins has springs which are close enough to the right size in either standard or DBH fitting. Should I have a DBH Spring in this barrel? Note there is a corresponding long slot in the barrel cap to match the one shown above in the barrel as well as another slot in the cap which will line up with the hook in the barrel wall.

S