NH35 Automatic Movement
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Complete Your Build
The Seiko NH35 is the most widely used automatic movement in the Seiko modding community. Manufactured by TMI (Time Module Inc.), a subsidiary of Seiko Instruments, the NH35 delivers reliable automatic timekeeping with a date complication at three o’clock, hacking seconds for precise time-setting, and hand-winding for quick startup after sitting unworn. If you are building your first Seiko mod or replacing a worn movement, the NH35 is the caliber most builders reach for.
Specifications
| Specification | Detail |
|---|---|
| Caliber | Seiko NH35A |
| Type | Automatic |
| Frequency | 21,600 bph (6 beats per second) |
| Jewels | 24 |
| Power Reserve | 41 hours |
| Hacking | Yes |
| Hand-Winding | Yes |
| Date | Yes (at 3 o’clock) |
| Stem Position | 3 o’clock |
| Rotor | Bidirectional |
Compatibility
The NH35 is a standard-size automatic movement that fits every Nomods case platform: the Royal Oak 37 mm, the Royal Oak 41 mm, the Petrichor field watch, and the Seikonaut nautilus-style case. It accepts both solid dials (waffle, , index) and skeleton dials, though solid dials are the most common pairing since the NH35 has solid bridges with no open-worked decoration.
Dial sizes: 28.5 mm dials for the Royal Oak 37 mm and Petrichor cases · 30.8 mm dials for the Royal Oak 41 mm and Seikonaut cases
Hands: All Nomods hands are compatible with the NH35 movement. Crown sits at 3 o’clock.
What’s Included
- Seiko NH35A movement (fully assembled with rotor)
- Stem
- Movement specification sheet
Why This Movement
Nomods uses the NH35 as the default movement in the majority of its builds because it strikes the ideal balance between reliability, availability, and functionality. The date window at three o’clock suits everyday wear, hacking seconds let you set the time to the exact second, and hand-winding means you can start the watch without shaking it after a few days off the wrist. The NH35 has been in production for years, parts and documentation are widely available, and it has earned its reputation as the gold standard movement for Seiko modifications.
Frequently Asked Questions
What is the difference between the NH35 and NH36?
The NH35 has a date-only complication, displaying the date in a window at three o’clock. The NH36 adds a day wheel, showing both the day of the week and the date. Both share the same 21,600 bph frequency, 24 jewels, 41-hour power reserve, hacking, and hand-winding. Choose the NH35 if your dial has a single date window or no date cutout, and the NH36 if your dial has a day-date aperture.
Will the NH35 fit my Nomods case?
Yes. The NH35 fits every Nomods case platform — the Royal Oak 37 mm, Royal Oak 41 mm, Petrichor, and Seikonaut. All Nomods cases are designed around the NH35/NH36 movement family. Pair it with a 28.5 mm dial for the 37 mm and Petrichor cases, or a 30.8 mm dial for the 41 mm and Seikonaut cases.
How accurate is the NH35 movement?
The factory specification is ±20 seconds per day. In practice, most NH35 movements run well within that range, and accuracy can be improved further through regulation by a watchmaker. For a movement in this price class, the NH35 is considered highly reliable and consistent.
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