Service: Omega Dress Watch with 625 Movement

 In Watchmaking

This time an Omega dress watch on the bench. It’s powered by the Omega 625 movement.

It was presented to a Mr. Ray H. Cline by the Edison Institute to commemorate his 35 years of service.

The serial number starts with 39… and that dates it to 1975. Mr Cline must have started working for the institute around 1940.

The movement didn’t run at all so it needed to be checked and serviced/repaired.

Disassembly

Remove all power from the mainspring. If you don’t, you might damage the pinions of the wheel train.

Move the click away from the ratchet wheel while slowly letting the crown slip between your thumb and index finger. Use a peg wood or watchmaker’s pick to move the click away from the ratchet wheel and lock it into place.

Remove the balance and the pallet fork with the pallet cock and store them somewhere safe. I believe that a lidded tray is the best option to keep it safe from harm and protect it from dust.

Turn the movement around and remove the cannon pinion.

Omega with 625 movement

Balance and pallet fork removed.

As you can see, the train wheel bridge and the barrel bridge from the Omega 625 are one piece. They call it a ¾ plate bridge.

Remove the crown wheel and the ratchet wheel. Both screws are regular screws. Usually, the crown wheel screw is left-handed but this one isn’t.

Omega with 625 movement

Ratchet wheel and crown wheel removed.

Remove the 3 screws and lift the ¾ plate bridge to get access to the wheel train.

Omega with 625 movement

The ¾ plate bridge removed.

Take out the center wheel, third wheel, fourth wheel, and the escape wheel. When I lifted the center wheel, I noticed that it was stuck to the third wheel with some sort of hardened drop of oil or grease. That looks to be the reason why the movement didn’t run at all.

The special design of the escape wheel must have some technical function but I’m not sure what it is. If you do, please let me know in the comments.

Lift the barrel.

Omega with 625 movement

Top plate completely empty.

Flip the movement around to work on the bottom plate.

Remove the motion works and the keyless works.

Omega with 625 movement

Bottom plate completely empty.

Pre-clean the pivot holes and bearing jewels with a peg wood. There’s also some sort of caked dirt on the bottom plate. Remove as much dirt with a peg wood or cocktail stick as you can.

Clean all the parts in the watch cleaning machine.

Assembly

In most cases, the first thing you need to do is fit the set lever with the set lever screw. This is a fiddly job so it’s best to do it with an empty base plate. In this case, you can skip this part because the 625 has a set release button instead of a screw.

Fit the barrel, the escape wheel, the fourth wheel, the third wheel, and the center wheel.

Omega with 625 movement

The barrel and wheel train reinstalled.

Place the ¾ plate bridge in position.

Omega with 625 movement

The wheel train bridge / barrel bridge fitted.

Install the barrel bridge, the crown wheel, and the ratchet wheel.

Test the wheel train to make sure that all wheels move freely and without much effort.

Turn the movement around and fit the motion works and the keyless works. The set lever spring acts as a check spring, cover plate and it also secures the set lever.

Omega with 625 movement

The bottom plate reassembled

Turn the movement around and reinstall the pallet fork. Wind the watch a couple times to test the escapement. The pallet fork should snap to the other position with the lightest touch.

The movement should start to tick as soon as you place the balance in place.

Now it’s time to remove the Inca jewel holes with the end stones to clean and lubricate them.

I slightly panicked because the Inca spring on the bottom plate pinged away when I opened it. The movement itself is 17.5 mm in diameter so you can imagine how small the Inca springs are.

I searched online for a bit and it looks like the Inca spring on the bottom plate of the Omega 625 is infamous for doing that so be careful! 

Luckily, it was still on the bench mat and I was able to reinstall it by carefully holding it in place with a cocktail stick while closing it with my trusty tweezers.

If it pinged away and disappeared from the face of the earth, you need an Inca spring 270.02

Place the hour wheel and washer in position, fit the dial and the hands and case the movement.

Omega with 625 movement

What do you think of this Omega dress watch? Do you have an Art Deco style Omega watch in your collection? Let me know in the comments below.

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