Horological Meandering

I have been to a number of Swiss workshops including V-C, JLC, BP, PP, Fleurier, etc. Everyone tests their watches to some degree - though JLC explains their Master Control 1000 hr test as one of the best.

I have the best pictures to share with you from my guided tours through Grand Seiko a few years ago.

What is "Grand Seiko Standard"?

The Grand Seiko Standard is a Seiko-exclusive accuracy standard for mechanical watches which has been established to ensure superior performance of Grand Seiko mechanical watches irrespective of the differences in environmental conditions in which a watch is used. 

"Grand Seiko Standard Inspection," which measures gain / loss (daily rate) under various environments, is carried out at the manufacturing plant for ~400 hours, 17 days in total, and only mechanical watch movements  that satisfy the standard are given the title of "Grand Seiko."

The Grand Seiko Standard differs from the other recognised chronometer standards in two important respects. 

1. While most accuracy standard testing is done for five positions at two temperatures, the Grand Seiko Standard tests six positions at three temperatures. This is because the Grand Seiko Standard seeks to replicate real world conditions. The sixth position, namely the 12 o’clock upright position, is the way many people place their watch when not wearing it. 

2. In addition, the extra temperature rating is closer to body temperature. The idea is simple - to test the watch under conditions similar to actual use.

Inspection of the movement for the Grand Seiko Standard Inspection Certificate is made prior to casing. Movement performance is carefully measured in the static positions under scientifically controlled conditions. 

HOWEVER, the accuracy of the watch may vary depending on the actual usage conditions and may differ from the certified accuracy.

Checking the watch yourself at home

The accuracy written on the Grand Seiko Standard Inspection Certificate is the accuracy of the Grand Seiko mechanical watch movement at rest, which is measured before the inside movement of the watch is assembled in the case. Since the accuracy of a mechanical watch varies slightly depending on individual user conditions, the actual accuracy during use may differ from the numerical value specified in the certificate. The accuracy is affected by conditions such as winding state of the mainspring due to movement of the users’ arm, ambient temperature, and posture (direction of the watch).

The target accuracy range of Grand Seiko mechanical watches in use is -1 to +10 seconds per day. To determine accuracy in use, measure loss / gain under normal use conditions for approximately 7 to 10 days and calculate the average loss / gain per day.

Are There Other Quality Checks?

Of course, the rate checking is only one factor. GS inspects the watches for water tightness (resistance), pressure/vacuum, visible flaws, polishing reflectivity, etc.

Cazalea

PHOTOS

Here are some images to show you how the process looks. It's a little different on manual or automatic wind watches, as the rotor must be placed onto the automatic watch after rate adjustment.

FINAL INSPECTION ROOM

ADJUSTMENT OF THE RATE

DEMAGNETIZING AND INSTALLING ROTOR

SPECIFIC DIALS & ONE HAND ARE INSTALLED FOR TESTING

WATCHES UNDER TEST ARE VIDEO-TAPED SO ANY ERRORS CAN BE ISOLATED

HEATING THE CASED WATCH MOVEMENTS ON LABORATORY STOVE TOP PRIOR TO LEAK TESTING

  login to reply