Kirkwood Skeleton 63A123 Automatic

I have a newer Bulova with the Sellita SW 200 movement. After nearly 2 months of adjustment, I am pleased to announce I’m getting an accuracy level of less than 1 sec/24 hrs. It is quite consistent with hardly any nighttime swing. I have been told this level of consistent accuracy is not possible with the new movement. I have been documenting the offset against the atomic clock every 24 hrs without resetting the watch to get a weekly/monthly result. Has anyone else had such good results with this movement or is this a complete anomaly? Thx, Jonathan Williams, Louisville KY  

 

Reverend Rob's picture
Reverend Rob
Posted November 4, 2017 - 10:44pm

Panel Member

Errors in rate will occur for many reasons, not the least of which is the movement of the watch on the wrist. Shocks, temperature, and positional errors all conribute to rates drifting or being altered. If your watch is achieving this rate while being worn, it is an exceptionally well regulated watch, or the many errors are cancelling each other out. 

The actual rate analysis utilizes a minimum of three and up to six positions. Three for most non-COSC watches and Six for COSC watches like Pateks and Rolexes. Most COSC watches are regulated to Five positions. They must exhibit less than 4.5 seconds Delta in all positions to obtain a COSC certificate, in different power levels, and at different temperatures. Wristwatches tend to stay warm on the wrist, so may vary in rate at night or in cold or hot weather.

The key word here is the Delta. You can dial the watch in to a second or two a day in the flat, but it must not change when rotated and timed in different positions by more than the COSC standard. This is actually harder than it sounds, and watches with significant wear do not rate well. 

A brand new Sellita, properly adjusted might perform well when worn, as I say, it is possible that the positional errors are cancelling each other out (A common goal in servicing older watches, for example) but it might be difficult to adjust to COSC Spec. That said, I have personally worked on many Breitlings that utilized the Sellita Chronometer movts, and all Breitlings after 2004(?) are COSC Chronometers. 

I've had only a few brand new watches perform as well as yours, ones that were not intended to be Chronometers. One was a Sea-Gull. 

Regardless, it is the performance on the wrist that is important, and yours is doing very well indeed. 

JonathanHWilliams
Posted November 7, 2017 - 8:49am

It appears I spoke a bit too soon regarding that last comment. As of late, the 24 hr average is still less than 1 sec/day HOWEVER, there is a loss of about 2 sec during the day and an equal gain at night when not wearing it. It is still quite accurate overall but is now showing a much greater swing than before. The only variable that has changed is I am no longer winding it—just allowing the self winding mechanism to do the work. That being said, it is never fully wound anymore which may account for the swing. What do you think?

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Reverend Rob
Posted November 7, 2017 - 11:50am

Panel Member

As long as you are fairly active the watch should be more or less 90-100% wound after a normal day.

Automatic watches utilize a slipping bridle to compensate for when the mainspring is fully wound, and the mechanism keeps on trying to wind it. If you are hand winding it, when you get to full power, there will be a point where you can hear or feel the mainspring 'slip'. A watch that is maintained at higher power will be more stable in rate. 

Handwinding certain automatics will add wear and tear to the mechanism, especially in the case of a 2824 based movt like the Sellita. I don't recommend getting in the habit of hand winding these watches every day, you reserve that for the odd day where you don't wear it, and want to keep it going. Your watch is performing extremely well.

JonathanHWilliams
Posted November 8, 2017 - 7:56am

Thank you. I am beginning to question whether or not I may have already damaged the auto winding mechanism by doing just that. What a shame—I just didn’t know it was that sensitive. It used to not spin freely when the watch was fully wound. Now it just spins with no resistance no mater the spring tension. Is this an expensive repair? It didn’t damage the actual movement any. I will mail it back to Bulova service for inspection. I just acquired an Accutron 65B001 yesterday used but in good shape. I will not be hand winding this one I can tell you! I bought it for a song from a pawn shop. It’s authentic but I’m not sure the employee knew what he had. Works great. 

JonathanHWilliams
Posted November 9, 2017 - 9:07am

I contacted Bulova Service in New York and advised the issue of the winding mechanism, he advised to monitor for 2 weeks and I’d a condition exists, they will repai it under warranty as it’s only 3 months old. 

Reverend Rob's picture
Reverend Rob
Posted November 10, 2017 - 11:04am

Panel Member

At full power, the rotor will appear stiff and not move easily. This is normal. 

The 2824 is a Bidirectional winding automatic, so it shouldn't spin freely in one direction after being wound or worn, like the 7750 does. 

The wear and tear I mentioned has to do with the crown wheel and winding mechanism, although it is possible to accelerate the wear of the mainspring through excessive hand winding, but the key word here is excessive. From a dead stop, 30 half turns of the crown will take it to full power, possibly beyond. Watch winders have ranges that can be adjusted to ensure the watch is only being wound enough to stay running and not constantly being wound to slippage.