Omega Seamaster 300 assembly

[Tudor]

So, as some of you know, I’m seeking a case for this watch. I have an aftermarket one, but it is not 100% compatible. Particularly the bezel. Also the case was completely polished, which is not correct, so let’s address that too. 

First thing is we need to set the crystal. The case came with one that’s falling out. It even has a tension ring, which is also falling out of the crystal. I have a genuine crystal, that’s a tight fit, but I’d rather save it for a real case than waste it on this one.

Clean the area where the crystal sits and apply a bead of G-S cement. First I had to grab it with the crystal lift. But more first I had to fix the crystal lift... It’s a nice Swiss one but used. And old. The original o-ring that expands the fingers replaced by a rubber band, which had hardened and cracked. I took it apart, cleaned and lined it, tightened the screw and added some o-rings to open the fingers. NOW we can put in the glue and set the crystal. 
 

While that’s drying, I decided to address the case finish  the sides of the case should be nice linear brushed, not polished  I put 600 grit on the side of one of my aluminum dies and keeping the case flat on the mat, I drag it across the paper. Maybe 400 would have worked but I’m happy with how it looks  

 

[Tudor]

The movement has been sitting a few years now. It sprang to life instantly but with a weak wind it was showing poorly... I’m debating tearing it down or not ... it would certainly look nicer if I cleaned it up. 

[Tudor]

I did drop the movement in and verify it fits (yes) and that the stem lines up with the case bore (yes). I put the stem on the crown. It’s an Omega manual wind crown; I have the later screw down crown but not the tube. I grabbed this crown off eBay because it’s 6.5mm OD and fits a 2.5mm tube, which is in the case. O-ring is still soft in the crown so it’ll do fine after lube. 
 

If I don’t overhaul the movement I’ll probably be wearing this tomorrow. 

Edited October 4, 2020 by Tudor

[rodabod]

I wear a Seamaster 300 mainly which I assembled from NOS parts. You got the case nicely grained. Looks the same coarseness as mine. 
 

Your timegrapher trace looks a bit ropey! I’d give it a clean if I were you. Or wait until you get the proper case. 

[Tudor]

Yeah, I bought most of the parts when they were available, but I didn’t get the case. Foolish. 
 

I found that the Rolex 16610 crystal retainer gasket is the right size for this case. I have no idea if the genuine case gasket is the same, but the genuine case back fits this case perfectly. 

If the bezel was remotely similar, I think this could be serviceable. 

[Tudor]

Finally back on this and I’m going to overhaul it. Pinions looks dry so I oiled the  visible ones and there apparently was still old oil in there because it’s been running worse and worse since. 
 

It looks a bit grungy on the polished surfaces anyway so I’m going to do it. Hopefully it doesn’t take a month. 

[Rocket]

Going to be a great watch! 

Looking forward to see how pro`s do it.

[Tudor]

Wrong thread if you’re looking for pro work...

[Tudor]

Ok. Back at it. I got a half hour so I figured I could get it torn down and rough cleaned.

I got it most of the way down (balance wheel and keyless to go) and the parts I removed are rough cleaned. Already looks a million times better. There was a huge hairball on one of the going train pinions. I tried to get a picture but I don’t know if it came out. Also some green skudge around the stem area. 

And I forgot about their cool stealth reversing wheel system. So, you need two ratchets to wind in both directions, but this 565 has only one on the winding bridge, which makes it quite small (compared to a 1535 or 3135 with two) so how does it work?

Well, they hide a ratchet wheel on top of the wheel on the barrel. I had forgotten about that and was like “what the heck is this tiny screw on this wheel for?” Once I had it apart I remembered the clever system. 

Next bit of fun is the seconds hand pinion. It’s on the winding bridge with a friction spring. And it’s about the diameter of a hair. I can barely see it under the loupe! I managed to not lose it somehow. I did have a few scares however. 

That’s about it for today. I have some pictures I’ll use for reassembly (minus the hairball) and here are a few of them...

[Watchtime]

Great watch....a lot of hairs in it, how is that possible... Maybe from a previous service?

[Tudor]

It was harvested from a square case watch which did not have any waterproof sealing. And, based on the condition of the screws, it may have NEVER been serviced.

When I acquired it, quite a few years ago now, I did the dial and date wheel swap and stored it while I waited for a case. I did not realize it would be a decade and I'd still not have a case...

Anyway, it is clearly in need of service, and I'm doing it now.

I also need a date spacer ring for under the dial, if anyone has a 565 date spacer ring...

[Tudor]

And the rest of the disassembly pictures:

[Watchtime]

nice job...a fair amount of dirt left behind in the jar...:)

[rodabod]

Do check the centre wheel side-shake while you have it stripped down. Give the canon pinion a wiggle. It is a common fault on examples of this movement which have led a hard life. 

[Tudor]

The center wheel seems tight but I will check again with it clean. And the canon pinion is quite tight. It did not want to come of...

The keyless works were especially nasty. And the main plate notch, where the stem enters, had some particularly stubborn green growth I had to scrape with plastic tweezers. I’m debating a more aggressive wash for this...

But do keep the tips coming! I wasn’t able to locate my hard copy of the service sheet on this so I have to check the hard drive today. Worst case I have to google it, which can take a while sometimes. Maybe Cousins has it...

[Tudor]

I found my parts list, but I don't have the oiling chart.

Should I just go with "instinct" and the ETA and Rolex charts as a guide? Just wondering if there are any "special" considerations in this. I don't want to tear it down again in a week...

[rodabod]

The reversers are the only part which require special attention. I think the last one I serviced, I dipped them in etalube or whatever ETA call it - lubricant suspended in a solvent. Or you can possibly thin some 9010 in essence from memory to make a similar cocktail. 

[Tudor]

I haven’t pulled the winding bridge apart yet. Currently it’s working fine. It got a dip in the Ronsinol (assembled) but that’s it so far. 

I may bring the main plate into work for an ultrasonic bath. (I really need a working one at home!)  It’s pretty nasty and my rubbing to clean it is becoming apparent. I may try some more aggressive cleaners as well. 

Bonus: I noticed some green ugliness on the underside of the balance wheel. It’s already been dipped but I think I need to get that wheel fully sterilized prior to assembly. I can already tell regulation is not going to be fun the way it is now. 

I can make some “special sauce” for the reversers easily enough. 

Edited October 16, 2020 by Tudor

[rodabod]

If there is green verdigris on the main plate then I'd maybe try an ammoniated cleaner if you can get one.

[Tudor]

Yes, either that, or dilute acid. I have a couple things in mind to test. 

[canthus]

I use the small dental brushes (for flossing teeth) for cleaning holes, tubes etc in main plates, bridges etc.  Only limit is diam of twisted wire used to make them. They come in several sizes and bristle stiffness.  Easy to dip in your cleaning fluid.

The centre second spring should be supported when fitting the centre second hand. There is a simple test for the correct spring force but just can't remember it at this moment.

[rodabod]

I think when the auto bridge is fitted, this actually effectively supports the sweep friction spring. But without it fitted, yes, absolutely, you need a firm support behind it. The spring should drop the amplitude by somewhere in the region of 5-10 degrees.

[Tudor]

I have a center support in my movement holder so this is no problem. 
 

Thank you all for the info and ideas!

[canthus]

Browsing again, I noted the way the balance assy is on the balance tack.  I would think that this could result in the h/s getting badly twisted if it accidentally fell off.  Why not just keep the assy on a flat surface if you want to keep it this way. I know many people let the balance dangle on the tack, but I think this also lends to the risk of the h/s getting damaged accidentally (particularly with small calibre (ladies) balances with very fine h/s).  I would only use a tack suspension for working on the balance. 

[Tudor]

It’s on the tack with the wheel in the jewel under a dust cover for longer term. It was dangling before and after dipping only. 
 

I find it is safer to lift from the tack than in the parts tray.