How to improve beat error on an Omega 601

[DanB]

Hi all, 

Just serviced this Omega Cosmic (the one I asked about crystal installation recently) and I'd like to improve the beat error before I close it up. From what I can tell through physical inspection, and from what I have read, it looks like the stud holder should be movable, but it won't budge when given a nudge. I gave it multiple stronger pushes and still no luck (well, I think it moved a minuscule amount because the beat error went down by .1 milliseconds). It's an excenter regulator. I want to avoid much manipulating of the balance assembly - particularly the hairspring - to avoid any disaster. I can live with 1.2 milliseconds of beat error, but before it goes back into the monocoque case, I'd like to give it one more try if possible. 

Thanks!

 

[Klassiker]

Disassemble, clean and lubricate the adjuster assembly, then set the watch in beat. 

[JohnR725]

always nice if you would give us a picture of the problem just to avoid any complications. then if you really want accurate amplitude measurements it would help if you had the correct lift angle which is 49.0. looking at the parts list the stud holder is definitely movable but it still be nice for us to see a picture because normally shouldn't have to lubricate them.

[DanB]

Thanks for the suggestions. I'll have to build up the nerve to disassemble the adjuster assembly, though I think I can take this project on in phases; remove the hairspring first, then see if the arm holding the stud can be coaxed. I know what direction it should go. The balance assembly has been throughly cleaned both with L&R Extra Fine in the electrosonic and a soak in One-Dip. I'll include a photo of the assembly if I take the next step. 

[rodabod]

Great performance there - i’d just leave it as is. But if you really want to then I’d take the advice given already to free it up with the balance removed. 

[DanB]

Here's the balance assembly with balance complete removed. I tried moving the beat regulator with the balance off but had no luck. It made me think this really wasn't intended to be moved since I applied a fair amount of force, but Omega in its 551 technical guide it says it should (different balance assemblies for each movement but same design on the underside). I'm guessing that the U-shaped spring (Omega calls it a "bolt") has to be slid out, freeing up the regulator arm. Then I could apply a tiny bit of lubricant to where the spring slides back in and test the regulator arm movement before replacing the balance. 

Given my previous experience with working with balance assemblies - ruining two on two inexpensive watches - I have some serious hesitation disassembling this one. In those situations it was the hairspring that was the victim. Removing the hairspring on the Omega was relatively easy, so that is safe for now. My worry is the difficulty I may encounter putting that spring/bolt back into place. It's easier to say goodbye to a $25 watch (my previous blunders), not so much an Omega.

Any words of advice will be appreciated.

 

 

[JohnR725]

I have an image for a different Omega but they should all be the same. As you noted you slide out the little U-shaped clip. Then the whole thing comes apart just pay attention to the order in which it goes back together. I have an image that should help you.

then it might be in my imagination but is your stud holder bent?

[DanB]

Hi John,

Yes, that's the image I have as well. Very helpful. I don't think the stud holder is bent - it could just be the angle at which I took the photo. But I will look more closely at it. 

So that U-bolt holds the whole works together? That means everything comes apart, including the rate regulator, etc.?

[JohnR725]

5 minutes ago, DanB said:

So that U-bolt holds the whole works together? That means everything comes apart, including the rate regulator, etc.?

yes everything comes apart when that slides out.

[DanB]

Well, clearly I have not taken one of these apart down to the studs, so to speak. I think I'll practice with a couple balance assemblies I have lying about, then see if I have the nerve to tackle this one. 

Thanks again for all the suggestions.

[DanB]

I practiced on a Hamilton 661 balance assembly (has an excenter regulator like the Omega 601), took it apart, and it was a chore to get that u-bolt spring reinstalled. I got it back together, but I think the bottom of the incabloc setting suffered a bit as a result. That made me take a closer look at the Omega, and John was correct - there is a bend (two bends actually) in the bottom of the incabloc setting (similar to what I did to the Hamilton), photo attached. That could be what kept the beat regulator from moving in the first place. Rather than take that apart and potentially make matters worse when reinstalling the u-bolt, I switched balance assemblies with an Omega 550 movement I have (I checked the Jules Borel database and both movements use the same one). That got the beat error on the Omega 601 from about 1.4ms to about .4ms. Then I successfully adjusted the Omega 550's beat error from 1.4ms to .7ms - plenty good enough - by nudging the regulator arm. It did nudge, but I've got to say, it's hard to move which makes sense given how much resistance that u-bolt spring provides. You don't even perceive it moving, but the change shows up on the timegrapher.

A long winded way to give you all an update and to once again express thanks to all that took the time to weigh in. 

[Klassiker]

Well done!