“My 2824 reads 220° of amplitude — is that bad?” Before concluding that a service is due, eliminate three causes of false low amplitude in order, and only then look at the real mechanical causes.
Step 1 — Check the lift angle you entered
A timegrapher does not measure amplitude: it derives it from the lift angle you typed into the machine. A 3° error shifts the reading by about 6%, or some fifteen degrees. An NH35 (53°) measured with a default setting of 52° or 50° will display up to some fifteen degrees less than reality. Our lift-angle table gives the manufacturer's value: 50° for an ETA 2824-2, 53° for a Seiko NH35, 51° for a Miyota 9015.
Step 2 — Control the measuring conditions
Amplitude is only meaningful on a fully wound movement, settled for at least 15 to 30 minutes, dial up, with no rotor draining energy during the reading. On an automatic worn since morning, a midday reading means nothing. Also measure 24 hours after full wind: the amplitude drop between 0 h and 24 h says far more about mainspring health than the raw fully-wound figure.
Step 3 — Read the trace, not just the number
The timegrapher trace tells the story the number hides.
Step 4 — The real mechanical causes
Once false positives are eliminated, the causes to investigate are: aged or missing lubricant, dirt in the train and jewels, a tired mainspring that slips too early, magnetism (typical symptom: sudden gain), and finally axial play out of tolerance. Our lubrication-points table states which oil family goes where.
When should you worry?
A well-serviced modern watch holds 270–310° dial up depending on the calibre. Below 180°, amplitude becomes critical and the watch is close to stopping at around 150°: it needs a service, not a regulator tweak. At the other end of the scale, above about 330°, you enter knocking: the roller jewel hits the back of the fork horn and the rate runs away. An amplitude that is too high is a fault just like one that is too low.
Frequently asked questions
220° on an NH35 — service needed?
Not necessarily: the NH35's lift angle is 53°. First check that the machine is set to 53° and that the watch is fully wound.
Can amplitude be raised by moving the regulator?
No. The regulator affects rate (gain/loss), never amplitude, which depends on available energy and friction.
Want to read a trace like a watchmaker? The Décalibre curriculum breaks timegrapher diagnosis down trace by trace in its laboratory unit.