If you’re getting into mechanical watches or watch repair, one of the first tools you’ll hear about is a timegrapher.
At first glance, the screen can look confusing. You’ll see numbers like +5 s/d, 270° amplitude, 0.3 ms beat error, along with graphs and ticking sounds.
But once you understand what the machine is actually measuring, a timegrapher becomes an incredibly useful diagnostic tool.
In this guide, we’ll break down:
- What a timegrapher actually does
- What VPH means
- How to read rate (seconds per day)
- What amplitude tells you about a watch
- What beat error means
- Why lift angle matters
- How to read the timing graph
I’ll also reference the popular WeiShi No.1900 Timegrapher, which is one of the most common timegraphers used by hobbyist watchmakers.
What a Timegrapher Actually Does
A timegrapher is essentially a very sensitive microphone.
It listens to the tiny ticking sounds produced by the escapement inside a mechanical watch.
Every time the escapement unlocks, it produces a small “tick.” The timegrapher measures the exact time between these ticks.
From those measurements, the machine can calculate:
- How fast or slow the watch is running
- The strength of the movement
- How balanced the escapement timing is
This is why watchmakers often describe a timegrapher as listening to the heartbeat of a watch.
Understanding VPH (Vibrations Per Hour)
The first setting you usually choose on a timegrapher is VPH, or Vibrations Per Hour.
This describes how many times the balance wheel oscillates in one hour.
Common examples include:
- 18,000 VPH – older mechanical watches
- 21,600 VPH – many mid-range movements
- 28,800 VPH – most modern automatic watches
For example, a 28,800 VPH movement beats 8 times per second.
The timegrapher needs this value because it expects ticks at a specific rhythm. If the beat rate is set incorrectly, the readings will be inaccurate.
Rate (Seconds Per Day)
The most recognizable number on a timegrapher is the rate, usually displayed as seconds per day.
Examples might look like:
- +5 s/d
- –10 s/d
This means if the watch continues running at the same pace, it will gain or lose that amount of time over a 24-hour period.
A small deviation is normal for mechanical watches. Many well-regulated watches stay within ±5 to ±10 seconds per day.
Amplitude (Balance Wheel Swing)
Amplitude measures how far the balance wheel swings during each oscillation.
You can think of this like a pendulum in a clock.
A strong, healthy movement will swing wider, while a movement with friction or low power will swing less.
Typical amplitude ranges are:
| Amplitude | Condition |
|---|---|
| 270° – 310° | Excellent |
| 220° – 260° | Acceptable |
| Below 200° | Possible service needed |
Low amplitude can be caused by:
- dried lubrication
- friction in the gear train
- a weak mainspring
- dirt inside the movement
Watchmakers often use amplitude as a quick indicator of a watch’s overall health.
Beat Error
Beat error measures how symmetrical the ticking is.
In a perfectly adjusted watch, the tick and tock should occur at evenly spaced intervals.
Beat error measures the difference between those intervals in milliseconds.
Typical readings:
| Beat Error | Meaning |
|---|---|
| 0.0 ms | Perfect |
| 0.3 – 0.6 ms | Very good |
| 1.0 ms or more | May need adjustment |
Large beat error can indicate the escapement is slightly out of alignment and may need regulation.
Lift Angle
Lift angle is one of the more technical settings on a timegrapher.
It represents the portion of the balance wheel’s swing where the pallet fork is actively pushing it.
The timegrapher uses this value when calculating amplitude.
Different movements use different lift angles. For example:
- Many ETA movements use 52°
- Some movements use 50° or 54°
If the lift angle is set incorrectly, the amplitude reading will also be incorrect.
This is why it’s important to know the lift angle of the movement you’re testing.
Reading the Timegrapher Graph
The graph on the timegrapher screen shows each tick from the watch plotted over time.
Healthy watches usually produce straight, clean lines.
Irregular patterns can indicate potential issues such as:
- low power reserve
- worn components
- dirt in the movement
- inconsistent escapement timing
Experienced watchmakers can often diagnose movement issues simply by looking at this graph.
Using a WeiShi Timegrapher
A popular entry-level machine for hobbyists is the WeiShi No.1900 Timegrapher.
It allows you to:
- set beat rate (VPH)
- adjust lift angle
- measure rate, amplitude, and beat error
- view the timing graph in real time
Because of its affordability and simple interface, it’s commonly used by beginner watchmakers and collectors.
Final Thoughts
A timegrapher may look complicated at first, but it’s simply a tool that listens to the rhythm of a watch.
By analyzing the timing of each tick, it can reveal:
- accuracy
- movement strength
- potential mechanical issues
For anyone learning watch regulation or watch repair, understanding how to read a timegrapher is an incredibly valuable skill.