Hello all, I'm currently restoring a Landeron 48 movement as an ongoing amateur personal project. After fitting the gear train the watch seemed to be running quite happily, I don't own a timegrapher, but cross-referencing a handful of timegrapher mobile apps the rate seemed to be okay. To measure the amplitude I took a slow motion video and gathered that the amplitude was around 260°-255° dial down (a very crude and inaccurate method, but without a timegrapher it was the best I could do). I had planned to go into town and ask a watch AD if they wouldn't mind putting the movement on one of their timegraphers, just so I could test in other positions, however, after coming back to the movement after 15 hours, leaving it running overnight, the amplitude has dropped to around 180°. So my question: is this acceptable for a movement of around 80 years old? May the watch just need to settle in as it was completely inoperable when I started work? Other points to note- it has the original blued steel mainspring, I don't know if this may be the cause of the issue, and I haven't fitted the chrono works yet, so what I'm measuring is just the gear train. Thanks in advance! Ed
That is a steep drop in that amount of time, and likely because the old mainspring is set (has lost it's original shape). I really never put blued mainsprings back in, as they don't give good performance, and are prone to breaking, which can cause significant damage. I would replace that spring with a modern white alloy spring. Cheers, Al