Glossary · Regulation
Lift angle
The balance angle used to describe escapement lift and calculate amplitude on an acoustic timing machine.
Explanation
In the lever-escapement explanation used by WahaWatches, lift angle spans the balance movement between entry and release of the impulse pin at the fork. It is a characteristic of the escapement geometry, not the full swing of the balance. Amplitude describes that much larger swing. The two angles therefore answer different questions and should not be entered interchangeably in a record.
An acoustic timing machine infers amplitude from the timing of escapement sounds and the entered lift angle. A default setting is an assumption, not a measurement of this calibre. An incorrect value can distort the displayed amplitude without making every other field on the trace meaningless. Use identified calibre documentation, retain the value and its source, and mark amplitude provisional if the lift angle is unconfirmed. Do not transfer a value from a similarly named movement without checking its variant.
Sources & references
- https://wahawatches.com/watch-talk-whats-the-lift-angle-of-a-watch/
- Reymondin et al., The Theory of Horology — construction and terminology further reading
Where sources disagree, the disagreement is stated rather than resolved silently.
What to record
- Record the entered lift angle and its source.
- Keep amplitude, rate and beat error as distinct fields.
- State when the instrument was left at an unverified default.
Do not mark a balance or manipulate stored power to estimate lift angle as an owner experiment.