This Omega 2416 came in a batch of watches to look at. It didn’t run, it was dirty and the crystal was in a terrible shape.
The movement is an Omega 28SC with an indirect sweep second. The concept wasn’t that successful as it had a few problems.
The second hand would often stutter as it’s not in the direct flow of power from the gear train. Also, it adds an extra layer to the movement, resulting in a thicker movement. It still lasted for 6 years, though. After the movement was relisted as the 370 they probably used it for another few years.
It’s possible to look up the serial number on the charts available on the internet. They tell you that this particular serial number is from 1943, however, several sources state that the 28SC is in production since 1944. It must be one of the very first ones then.
The one thing that I immediately notice is the escape wheel bearing jewel. It’s completely topped off with old and gummy lubrication. You can’t even see the escape wheel pivot.
That will stop your watch or cause serious problems in timekeeping at least.
Remove the power from the mainspring. Lift the balance and the pallets. Then flip the movement to remove the hour wheel and the cannon pinion.
Because the movement doesn’t have shock protection the balance has to be disassembled further.
The balance complete can be cleaned by dipping it into One-Dip or something similar. All other parts (balance cock, jewel hole, capstone, and regulator) can be cleaned in the watch cleaning machine.
Lift the sweep second cock and the sweep second pinion. Then remove the driving wheel over the 3rd wheel.
You have to use a special tool for removing wheels with 5 spokes. I read that you can also use 2 small screwdrivers but I wouldn’t recommend it. The risk of damaging the 3rd wheel pivot or scratching the train wheel bridge is too high.
Remove the train wheel bridge and lift the gear train. Except for the center wheel because that is covered by the barrel bridge.
Lift the barrel bridge and then remove the center wheel and the main barrel.
Flip the movement and remove the set lever spring. Then remove the motion works and the keyless works.
Remember to pre-clean the movement and some parts with a pegwood. Don’t forget the pallet stones and the pallet horn.
Clean all parts in the watch cleaning machine.
Start with the main barrel and the gear train. Refit the train wheel bridge.
Reinstall the barrel bridge, the crown wheel, and the ratchet wheel. Then you can refit the sweep second pinion and the sweep second cock.
Be careful with replacing the driving wheel. You can use a hand fitting tool or one of the flat stakes from the staking set. Don’t press down until you’re sure that the driving wheel lines up with the sweep second pinion.
Try to install the driving wheel as true as possible. The sweep second pinion is not that thick and you don’t want the wheel to touch the train wheel bridge.
Flip the movement to reinstall the motion works and the keyless works.
Flip the movement back to reinstall the pallets and the balance. Don’t forget to oil the balance endstone before you reassemble the balance.
Refit the dial and the hands and recase it. I also polished the crystal while the parts were in the watch cleaning machine.
What do you think of this 40s Omega? Let me know in the comments below.