Newbee question (about mainsprings)...

Much better, so why not give us a full set of positional checks at full wind, and then again at 24 hours after full wind.

Note that full wind readings are taken between 30 and 90 minutes after full wind, so wait at least 30 minutes before starting the readings.

Cheers, Al

Yes those are the full set of readings - so 6 at full wind and 6 24 hours after full wind. And I would adjust the dial down rate to be slightly positive to start the test.

Cheers, Al

In fact they are useful. The graph below shows the effect an unbalanced balance wheel on rate for several amplitudes when the watch is in a vertical position (the graph doesn't apply for dial-up and dial-down positions). For example, the leftmost data shows the rates when the extra mass is located at the bottom of the wheel. We see at amplitudes below 220 degrees the watch will be fast and for amplitudes above 220 degrees the watch will be slow. If the extra mass is located at the top (middle section of the graph) then the reverse is true, that is, fast at high amplitude and slow at low amplitude. Looking at your data, for PD, it's slow (-40 s/day) at low amplitude and fast at high amplitude (23 s/day). This proves the extra mass is at the top of the balance wheel in this position (extra mass near 9 o'clock, assuming you defined the "pendant" as the crown at 3 o'clock). The rest of the data in the vertical positions also support this.

Sorry - had some surgery this week, so not posting much as I recover...

Anyway, seeing these numbers, they actually fall within Omega's accepted tolerances for this movement.

For the Cal. 266, the tests at Omega are only done over 3 positions, and the average daily rate should fall between -1 and +16 seconds per day at full wind. Your watch has an average daily rate of just under 3 seconds, so that's well within tolerance.

The Delta (positional variation) is allowed to be as much as 40 seconds at full wind, and 50 seconds 24 hours after full wind - remember this is only over 3 positions, and the larger number of positions you measure, the more difficult it is to keep the Delta number low. Your Delta at full wind is 34 seconds, so it meets the standards. Your Delta gets better at 24 hours after full wind, so again well within Omega's tolerances.

So what does this tell us? Mostly that Omega has very loose tolerances for these movements, and why I personally use them just as a starting point only. But overall this is a pretty good result for a watch of this age and with an inexperienced repair person. Often these movement have worn holes in the main plate and barrel bridge, worn out barrels, worn wheels, and all these lead to low amplitudes and timing issues, but none of that is present here, so I can pretty safely assume that the movement is actually in very good condition, and is not really worn out. So if that was all you had to report, I would say job well done.

Now about the strange noises, increase in beat error, and reduction in amplitudes, this is unusual. All I can say is that you need to observe what positions this happens in, and see if anything is rubbing, such as the overcoil of the balance spring contacting a wheel for example.

Until you sort this issue out, then set aside issues of poise and timing, because you need the fundamentals to be absolutely perfect before you move on to that process. Many things that may appear to be poise errors can be errors in the shape of the balance spring, so that in particular has to be absolutely perfect before you move on - you don't want to correct errors in the balance spring by messing with the poise, and that is a trap many inexperienced people run into when they learn dynamic poising as it becomes the "go to" solution for every vertical timing issue. It's like when the only tool you have is a hammer, everything starts to look like a nail...

You might also want to look for something like debris in the teeth of slower turning wheels, or perhaps a bent or damaged tooth. Ideally all these would have been inspected before assembling the movement, so you don't have to take it apart again, but check the barrel teeth for defects and the center wheel teeth in particular, since this sounds like a very intermittent issue that could be related to slow moving parts.

Regarding the "almost no wind" readings, these aren't really used unless you have already detected a poise error and are doing something about it. You don't need these readings to detect poise errors, as they are typically very evident in the full wind timing numbers, but low amplitude numbers (below 180 - I usually use readings in the 160's in vertical positions) to locate the heavy spot during dynamic poising. They may be usefuly for understanding how things change with poise errors and if the balance is accelerating or decelerating as it comes into and out of the lift angle, but they aren't used as a normal set of readings done in timing checks.

Let us know what you find with that noise...

Cheers, Al

Fully agree here.
The funny tracking you described should be looked into before poising and such. As Al suggested, it seems there might be an object that is interfering with the proper motion the movement at times.