Watch tech data explained

Product watch tables in the shop are full of tech data, below you will find more on this explained.

Lift angle - setting up a timegrapher

Even if you put your watch flat on the timegrapher, what you'll want to know about your movement is the lift angle. This is the angle the balance passes through while interacting with the pallet fork. The reason you need to input this into the timegrapher is so that you can calculate the amplitude. Also, when you will twist the holding bar of the grapher to vertical or any other position, you will have the correct starting point.

Most modern watches have a lift angle of 52 degrees. Generally lift angles range from 44 to 58 degrees

BPH - use autodetect unless you are sure it is wrong.

On screen - understanding the results

When you have Lift Angle, Amplitude and BPH on screen, you may now want to know what to look for. 

1) Standard Rate - How fast/slow the watch runs in seconds per day. 
This is the most basic statistic and will at least let you know how accurate your watch is in the flat standard position. If your watch is COSC certified, in order to be in good health it needs to be running between -4 and +6 seconds per day. Otherwise it will depend somewhat on the watch, but with a few exceptions you should consider the following to be a good range of your movement's health. If it is wildly out of these ranges, you should bring it to a watchmaker to get it checked out.
  • Excellent   +/- 7 s/d
  • Acceptable  +/- 20 s/d
Keep in mind that the daily rate when on wrist has a wider margin or variance as stated by the manufacturer. Seiko lists the 4R15 movement as -35/+45 per day.

2) Amplitude - the amount of rotation in the swing of the balance wheel in either direction. 
Amplitude is higher when a watch is lying flat and usually falls when the watch is in a vertical position, due to increased friction. Amplitude can also fall as the watch winds down and the mainspring delivers less power. This is why you should have your watch wound up to a medium tightness before testing.

Amplitude is indicative of the movements health, too high or too low, or too many changes in different positions, usually means a problem with the movement should be addressed.

  • great : 270-310
  • acceptable : 250-270
  • Low : 100-250

Keep in mind that Japanese movements seem to have lower amplitude than Swiss. Seiko will rarely go above 285 or so looking at the best GS vintage and medium tier 4R36 and 6R15 movements. With that in mind:

  • Great : 250-285
  • Acceptable : 185-250
  • Low : 155-185

3) Beat Error
How equal each swing of the balance wheel oscillation is.
  • Excellent : 0.0 - 0.5 milliseconds
  • Acceptable : 0.6 - 1 milliseconds