A question of method. The timegrapher screen shows up in almost every set of QC photos, but in the comment threads I see very different interpretations.
I count at least three positions:
- some look only at the rate (s/day);
- some say the rate in QC is almost irrelevant;
- some look only at the amplitude.
Before adding the timegrapher to my checklist, I’d like to understand which reading is justified. Current level of certainty: low.
Related threads: How long does a rep watch actually last, and what tends to fail first?, Swimming with a rep diver: does “pressure tested” actually mean it’s safe in the water?, VS3235/DD3235 clone or Asian 2824: what you gain and what you lose.
Good question, and the short answer is that amplitude is the most informative number, but not on its own.
Here’s why. Amplitude is the swing angle of the balance wheel: it shows how well energy gets from the mainspring to the balance. The community guides give roughly 230–300°, dial up, as an acceptable range. One of the guides notes that amplitude that’s too high is not a virtue: it can make the impulse pin “knock” against the pallet fork.
Jumping in in English, hope that’s ok! I always thought rate was THE number. If it says +2 s/day, isn’t that great?
In QC, not very meaningful. One guide explains the reason well: rep movements have a balance regulated with a regulator index, and the regulation can shift with knocks and vibration, which is exactly what happens during shipping. So +2 s/day in the photo doesn’t guarantee +2 on the wrist.
But another guide gives ±10 s/day, dial up as reasonable. It isn’t “ignorable”, it’s a threshold. The two sources don’t match.
Fair point, and in fact they don’t really contradict each other: ±10 is a reference for dial up, while the stricter guide says that within ±30 it isn’t worth worrying about at the QC stage. For comparison, the same guide points out that even a standard-grade ETA 2824-2 is “within tolerance” at ±30 s/day.
Sorry, what’s “lift angle”? It’s on every screenshot and nobody explains it.
From the guides: it’s a setting you enter on the timegrapher for the movement being tested, and it feeds into how amplitude is calculated. Many machines default to 52°. Set it wrong and the amplitude number is wrong too!
So a “low” amplitude could just be a wrong setting. To be checked case by case.
Here’s how I’d put it in a checklist, in order of importance:
1. Amplitude (°): the main figure
- Range given by the guides: roughly 230–300° dial up.
- Check the lift angle setting: one guide reports that +1° of lift angle raises the calculated amplitude by about 5–7°. If the value looks unusual, ask what setting the measurement was taken with.
- Context: amplitude is higher flat and drops in vertical positions; it also drops as the mainspring runs down. One guide suggests measuring at full wind, after about an hour.
2. Beat error (ms): the second
- Below about 0.7 ms it doesn’t affect the rate, according to one guide; another considers up to 0.7–1.0 ms acceptable.
- Clearly higher values deserve a question. One guide links them to possible hairspring problems.
3. Rate (s/day): the least reliable in QC
- Reference: about ±10 s/day dial up is reasonable; within ±30 is no cause for alarm in QC.
- It can change in shipping, because the regulation shifts with knocks.
4. What the photo does NOT tell you
- A single position doesn’t describe how it behaves on the wrist.
- It says nothing about lubrication over time.
And a warning I always repeat: regulating the movement yourself, without tools or experience, risks damaging the hairspring. Better to go to a watchmaker.
Clear and well reasoned. I’m adding it to the checklist with these weights: amplitude high priority, beat error medium, rate low. Marking it as the solution.
Saving this. “Check the lift angle before panicking” is my new motto!