Those who have been paying attention will recall my post last week, featuring the service and sorting of the 1972 Omega Constellation I recently acquired.
I'm v. pleased with the watch, it's been my 'go to' wearer for the past 8 days interspersed with wrist time for one I was testing. I didn`t spend much time regulating it, there's little point until a watch has run for a few days and settled, initially I thought it was losing a couple of seconds/day. However, I was surprised to see that it's kept excellent time over the week, and after 8 days it's lost a total of 5 seconds. It's losing a couple of seconds during daily wear but gaining slightly overnight in the dial-up position, to give a good overall average. I usually aim for a small gain based on 16hrs on the wrist and 8 hrs dial up overnight, I haven`t checked this one rigorously on that basis but clearly it's not worth regulating it further or messing around. I`ll settle for this............but what does the positional variation actually look like? I did a quick check when I assembled the movement and knew it was close. I'd previously inspected the hairspring v. carefully, adjusted the curb pins and checked the hairspring was centred between the curb pins, so there was nothing obvious to go at if it was way out. Anyhow, after one week's running here are the figures:
Dial up: +5secs/day, amplitude 274°
Dial down: +4, 275°
crown up: -9, 242°
Crown down: +3, 244°
Crown at 3: +1, 240°
Crown at 9: -9, 239°
Crown up and crown at 9 (crown left) figures are a bit low, I`d prefer to see a maximum span of 10 secs, but given the age of the watch these numbers are fine and I`ve no intention of trying to make further adjustments. The amplitude's OK too, a 30° drop between flat and hanging positions is fine and the results are fairly consistent. Fitting a slightly stronger mainspring would push the figures up but it's not necessary to do so.
One nice feature about these movements is the swan neck adjuster, it's possible to alter the rate by around 1 or 2 secs/day and there's no risk of losing the original setting. This makes it entirely feasible to fine-tune a watch, it's very easy to do. A magnifier and a very thin screwdriver are all that's needed, make a note of the screw-slot position and move the screw one eight of a turn to change the rate by a couple of secs/day.........but I think I`ll leave this one alone!