Barrel lid for comparison:

Wrong:



Right:



Old and replacement hour recorder bridge for comparison:







Best - Neil

 

As many have said, but a first time for me, I am glad we have Archer here as a contributing member to the Forum.

I like going back through his helpful posts and just reading all his watchmaker comments. Whether I understand fully or not it is informative and builds a base of knowledge I did not previously have.

 

Am I right in thinking it's Neil?

 

So just to add a bit to this thread, since I'm working on a 321 today I will show the barrel as it should be:



And the lid and hour recorder drive wheel inverted:



That was what I was picturing when I first read this thread...

And I know your watchmaker thinks that boss was intentionally machined away, but I would not always assume that original parts will resemble exactly the features of recent replacement parts. Just like replacement dials, crowns, pushers, etc. don't always look like the originals, very often replacement parts for the movement will have subtle differences. For example you used to be able to unscrew the heart cams from the chronograph runners and replace them, but modern replacements are permanently fastened together, so that's no longer possible. Sometimes new parts will have different finishes on them, so in some cases even though I have ordered the correct parts, I will hand finish them before I install them on the movement if they are visible through a display back for example.

I didn't want to say anything previously because I couldn't find a photo (I don't often take photos of the underside of this bridge) but if you look at one that is original to the watch, it also looks machined in this area:



So because the newer replacement part doesn't look machined on the underside around that boss, it doesn't mean they never were machined there when they were original parts. The boss on yours is gone, but I don't think I would conclude 100% that it was machined away, as it could be worn away...

Cheers, Al

 

Just to put some additional information in this thread, the bridge for the hour recorder on the watch I'm working on was worn - the hole is worn oval:



Same thing on the barrel and wheel train bridge:



You have to look closely for this, because the barrel arbor doesn't go all the way through the plate, so looking from the underside shows the lip of the original hole and how much wear is on this bridge:



I could just swap the part, but in a few extra minutes I had the old worn hole bored out for a bushing:



And the bushing installed - note how I used a thicker bushing and left it protruding to get the correct barrel end shake:



And the movement is now ticking along fine:



Sometimes replacing a part is fine, but other times repairing is far more cost effective.

Cheers, Al

 

Hi Al,

how do you determine if the spring tension on the recorder drive wheel is right?

And another more general question, when you inserted your bushing, did you use the 4 sided broach method to prevent rotation, or are things done differently now? Asking as my watchmaking references date from the 1960s.

Thanks,

Kris.

 

Hi Kris,

The drive wheel tension rarely has to be adjusted, but if it fails to drive the hour recorder wheel it has to be increased. If there's a problem, it's usually from a worn spring - you can sometimes flip it over if the wear is not too bad, or it can be replaced - this part is still readily available from Omega. I maybe have to replace one or two a year tops, and I service a lot of these movements.

The bushing is a press fit, so it won't rotate any more than a jewel would rotate in a plate or bridge...pressed in place using the Horia tool:



Cheers, Al

 

Hi Al,

thanks for that - so I guess you need to assemble and test then, or is there a way of predicting this before - assembly?

So do you ever have trouble when reaming after fitting, or do you only ream before?

 

No, not really. Of course you service the barrel as normal - clean, check for damage/wear, assemble without the spring and check/adjust end shake of the arbor as needed, then insert the spring, assemble the barrel, and install the drive wheel and friction spring. I then check how easily the drive wheel turns before I put the barrel in the watch - just spin it with my tweezers. I've serviced hundreds of these, so you do get a feel for what is the "right" tension. I've never put one together, and had to take it apart to change the spring or adjust the tension.

If you did though, you can likely remove the hour recorder bridge, and remove the spring and drive wheel without disassembling the rest of the movement. Usually if there is going to be a problem with the hour recorder, it will be creep from it moving when it should not, which is just a simple adjustment typically. Again it's rare that I would have a spring that was a problem, and it's usually from wear, which you can see.

On the bushings, I often ream with either the Seitz set or a cutting or smoothing broach after installation, and not had issues with the bushings turning. If the press fit is correct it really isn't a problem.

Cheers, Al

 

Thanks Al - that was very helpful.

As to the bushings, I'd not had troubles in the past either - but its not something I do often, and my last one failed badly. Actually on additional consideration perhaps the bush was undersized - I did uncharacteristically use a non Seitz bush that time.