NH38 Automatic Movement
Complete Your Build
The Seiko NH38 strips the date complication entirely, giving you a clean dial with no window cutout. Manufactured by TMI (Time Module Inc.), a subsidiary of Seiko Instruments, the NH38 belongs to the same movement family as the NH35 and NH36 and shares their 21,600 bph frequency, 24 jewels, 41-hour power reserve, hacking seconds, and hand-winding. Choose the NH38 when your build calls for a minimalist dial design where a date window would disrupt the symmetry.
Specifications
| Specification | Detail |
|---|---|
| Caliber | Seiko NH38A |
| Type | Automatic |
| Frequency | 21,600 bph (6 beats per second) |
| Jewels | 24 |
| Power Reserve | 41 hours |
| Hacking | Yes |
| Hand-Winding | Yes |
| Date | No |
| Stem Position | 3 o’clock |
| Rotor | Bidirectional |
Compatibility
The NH38 shares the same physical dimensions as the NH35 and NH36, so it drops into every Nomods case without modification: Royal Oak 37 mm, Royal Oak 41 mm, Petrichor, and Seikonaut. Because there is no date mechanism, the NH38 works perfectly with dials that have no date cutout — but it also works with date-window dials if you do not mind the blank space behind the aperture.
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 NH38 movement. Crown sits at 3 o’clock.
What’s Included
- Seiko NH38A movement (fully assembled with rotor)
- Stem
- Movement specification sheet
Why This Movement
The NH38 is for clean, no-date builds. When you want a dial with unbroken symmetry — no date window cutting into the indices, no day wheel cluttering the layout — the NH38 is the correct caliber. It shares every mechanical attribute with the NH35 except the date disc, so you are not sacrificing reliability or build quality for a cleaner look. Nomods uses the NH38 in builds where minimalist dial design is the priority, particularly in diver-style and field-style watches where the owner wants time-only display.
Frequently Asked Questions
What is the difference between the NH38 and NH35?
The only difference is the date complication. The NH35 has a date wheel that displays the date through a window at three o’clock. The NH38 has no date mechanism at all, resulting in a cleaner crown operation (one less position to cycle through) and full freedom to use dials without any cutout. Frequency, jewel count, power reserve, hacking, and hand-winding are all identical.
Can I use a dial with a date window on the NH38?
You can physically install a date-window dial, but there will be no date disc behind the aperture — you will see a blank space where the date number would normally appear. If you want a date display, use the NH35 for date-only or the NH36 for day-date.
How accurate is the NH38 movement?
The factory specification is ±20 seconds per day, the same as the NH35 and NH36. Removing the date complication does not change the timekeeping performance. As with all movements in this family, accuracy can be improved through regulation by a watchmaker.
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