Beat Error

[Maestro]

Hi,

I am buying (or in the process of getting) a ceramic Submariner from Lay at Replicamake. However one of the things he does for his quality control check is check the movement with a machine. But I'm not sure what the results mean?

I understand the +/- seconds a day is how much time the watch gains or looses. Please correct me if I am wrong. But the "beat errors" I'm not sure what this means. I believe he aims to have all watches under beat error 1. But lets say if the watch had a beat error of 0.3-0.8 does this mean the movement is good or that it is going to be unreliable?

Please help me in understanding these results!

Thanks!

 

[14060 or 16610?]

Getting the beat error as low as possible will make for more accurate timekeeping relative to outside forces such as inertia and gravitational pull. If a movement is grossly out of beat the escape lever can even lock up against the escape wheel and seize the movement altogether. Most watchsmiths, myself included, strive to adjust for .1 or lower. But I have shipped rep watches out with quite high beat error if there are hairspring or other issues that prevent it from being stable with lower beat error. Par for the course when you're dealing with reps.

But beat and rate numbers only tell part of the story in real time. Sort of like the speedometer in your car - it only tells you how fast the vehicle is going but doesn't tell you if the engine is running properly. You really need a Vibrograph analysis or equivalent to tell if the tick lines are straight and parallel.

Check out this example of a watch recently sent in to me:

The real-time rate during the screenshot is +10 seconds/day and the beat error is .5 or below. Not too bad, and some folks might be happy to get similar performance from their rep. But I assure you if you received this rep you would be most disappointed. See the zig-zag tick pattern? The movement was in terrible shape and erratic, going from running very fast to running very slow. The inconsistent hairspring and out-of-round wheels led to galloping and seizing of the escape lever. And the issues could not be resolved.

Just an example of how a Vibrograph-type analysis will speak volumes more than just generic beat and rate numbers.