Cal. 9S64 is a hand-winding time-only movement from Grand Seiko. It is extremely unusual in the family, lacking a date and being hand-wound. When it was introduced in late 2011 it was the only hand-winding movement in the line until the derived Cal. 9S63 was introduced in 2019.
Cal. 9S64 is used in the Grand Seiko SBGW line of watches in the Elegance collection.
Most examples of Cal. 9S64 are accurate to -3/+5 seconds per day when static. The special model SBGW251 was tuned for -1/+5 seconds.
Seiko 9S6x Family Overview
9S is the family of high-end mechanical watch movements used in the Grand Seiko and Credor watch lines. The current “3 days” 9S6x family debuted in 2006 with Cal. 9S67, and has replaced the Seiko 9S5x series over the following decade. The movement boasts 72 hours of power reserve thanks to a stronger Spron 510 or 610 mainspring and escape wheel and pallet form finished with MEMS technology.
Seiko boasts that these movements can deliver -3/+5 seconds per day accuracy in controlled static tests. On the wrist, the company claims -1/+10 second accuracy per day, and Seiko adjusts them in 6 positions. Adjustment is performed using a screw with index moving a mobile regulator for the flat hairspring.
The 9S family movements are constructed by hand at Seiko’s Shizukuishi Watch Studio in Morioka, Iwate Prefecture, Japan.
All watches in the 9S6x series feature hand winding, hacking seconds, and operation at 28,800 A/h. Most feature automatic winding with a central rotor mounted on five ball bearings. These use a conventional reverser wheel rather than the Seiko Magic Lever system found on the previous Cal. 9S5x series.
Seiko 9S6x Family
| Production | Models | Winding | Jewels | Date | Notes | |
|---|---|---|---|---|---|---|
| Cal. 9S61 | 2015-present | SBGR | Automatic | 33 | No | |
| Cal. 9S63 | 2019-present | SBGK | Manual | 33 | No | Power reserve at 3:00 Small seconds at 9:00 |
| Cal. 9S64 | 2011-present | SBGW | Manual | 24 | No | |
| Cal. 9S65 | 2010-present | SBGR | Automatic | 35 | Yes | |
| Cal. 9S66 | 2010-present | SBGM | Automatic | 35 | Yes | Central GMT hand |
| Cal. 9S67 | 2006-2010 | SBGL | Automatic | 41 | Yes | Power reserve at 3:00 |
| Cal. 9S68 | 2017-present | SBGR | Automatic | 35 | Yes | Larger size |
See Also: Seiko 9S6x Family