Vintage Chronograph Tolerances

[evese]

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 an 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 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 

[Nucejoe]

Did you replace the mainspring with new one? 

 

[evese]

12 minutes ago, Nucejoe said:

Did you replace the mainspring with new one? 

 

No I did not, although I think this may be the source of the issue. I was hoping to get away with it 

[Nucejoe]

1 hour ago, evese said:

 I was hoping to get away with it 

With manual wind, you stand a good chance, if you get a decent power reserve, which you can measure with a bench test, you might be happy with 35hrs reserve, the nominal is 41hrs.

It can keep accurate time, but expected to fail precision( expected precision is within seconds per day)  which is what you have paid for( since Landeron48 is a chrono grade).  Precision has to do with good amplitude.

The watch is worth a new mainspring.

Good luck.

 

[evese]

36 minutes ago, Nucejoe said:

Good luck.

Thank you for your advice! It's really appreciated  

[rodabod]

Ultimately, you want it to keep good time on the wrist. It may be well adjusted already, in which case achieving a strong amplitude is less critical. So, time it and see how consistent it is. 
 

Very generally speaking, 260 degrees is not bad. But, like I said, does it keep consistently good time?