Regulating An Omega 2500C That Is Far Off

[rb0087]

My main question is about regulating the 2500C, but I'll share some background on this particular movement first.

     A while ago, I bought a basket case Omega 2500C coaxial escapement movement off of eBay. It was very badly corroded, with most of the keyless works, automatic device, and other parts ruined. The train wheels looked bad, but the pivots were OK, with the exception of the fourth wheel, which was somewhat bent on the long lower pivot for the seconds hand. This picture shows one of the train wheels that hadn't been cleaned at all, along with the fourth wheel (with its bent lower pivot), which had started to be cleaned. 

    After a lot of work cleaning up the irreplaceable parts, which didn't look good (the balance was completely black, for instance), and replacing most of the other parts with those from a donor 2892 (also sourced from eBay), I finally have a working movement! When I first got this movement and realized how horribly corroded it was, I never thought this day would come. It doesn't look nearly as pretty as it did from the factory; all of the gold plating is gone, and the rhodium plating is spotty in places, but it works!

   This brings me to my question. I analyzed the timing with some watch timing software that can accurately analyze coaxial escapements, and the results show that it is running with good amplitude (300-315 degrees), and beat error of 0.36ms, but the rate is very far off, at about +1600 seconds per day. I've demagnetized and cleaned the hairspring. My guess is that the balance has lost significant mass as a result of the corrosion, resulting in a fast rate. 

   I've never regulated a movement with a free-sprung balance before, and I don't have the Omega special tool for doing so easily. Unlike a Rolex, though, the balance adjustment screws are just square, so it seems like they could be turned without a special tool. I'm concerned that I might break the balance pivots trying to do so, though.  So my questions are:

   1) Is it possible to adjust a movement which is this far off? 
   2) Can it be done without a special tool?

Thanks for any advice!

[DJW]

At this point I conceder you well ahead of the game! I'm sure Mark will one of the folks to reply to you and give very sound advice...

 

If it were me, I would try to see if the timing screws could be at least turned with very little pressure with a set of fine tweezers or something of the like. My biggest concern would be that the screws may still be corroded in place.

 

Also, I was recently working on a movement that was 1000+ sec/day. Since it was a movement that was adjusted to temp and positions, I didn't want to mess around too much with the compensated balance. I was able to let out the timing screws as far as I dare go with them, but was only able to slow it down by 500-600 sec/day. My biggest fear would be that there is not enough adjustment in the timing screws to slow it down enough.

 

Don 

[SeikoWatch]

Anyway, it's a nice job on it DJW :)

[Mark]

Well you have done an amazing job just getting this far as it's quite a sensitive movement - so hats off to ya  :thumbsu:

 

Whilst it is best practice to use the proper tool, they are simply screws and so you can turn them using any safe method you feel is fit. If you have used a micro stella tool in the past you will know that you should keep the screw heads exactly equal distances from the balance wheel. 

 

And I am sure you know that screwing out will slow the balance - inwards will speed up the balance.

 

Take baby steps - turning one screw by a quarter, then the next screw equally - test then do it again until you get a better reading.

 

And I recommend you do it with the balance out of the movement to reduce the risk of damage to the balance staff.

 

 

 

I analyzed the timing with some watch timing software

 

I am interested which software you are using?

[rb0087]

Thanks for the input! I'll give it a shot sometime soon and let you guys know how it went. I'm not sure that I can compensate enough with the screws, though. From the datasheet, one revolution of both screws changes the rate by 84 seconds/day. I may have to figure out something else.

 

The software that I've been using is the Watch Escapement Analyzer from Delph Electronics: http://www.delphelectronics.co.uk/products.html . They actually have a free demo version that you can try with some pre-recorded demonstration wav files. Since I'm just a hobbyist, I've just been using the free demo version with wav files that I record using an accelerometer attached to the movement holder (my day job is as a mechanical engineer doing vibration research, so I have this sort of equipment on hand). 

[Mark]

That may explain the reading being so wildly out. The demo version of this software cannot be calibrated (according to Graham Baxter) and so you may be getting a false reading - now I may be wrong but it's just a thought.

 

I was having a hellish time trying to calibrate the software, and I mentioned it to Graham when I picked up my laptop and microphone from him and he said the demo is limited in this respect.