Seiko’s NH series movements are renowned for their reliability, affordability, and versatility, making them a favorite among watch enthusiasts and modders. In this article, we’ll delve into the differences between the NH34A and NH35A movements and explore other notable NH movements commonly used in watch modifications.
NH34A vs. NH35A: Key Differences
NH35A: The Workhorse Movement
The NH35A is a widely used automatic movement featuring:
- Functions: Hours, minutes, seconds, and date display.
- Jewels: 24.
- Power Reserve: Approximately 41 hours.
- Frequency: 21,600 vibrations per hour (vph).
- Features: Hacking (stop seconds) and manual winding capabilities.
Its simplicity and robustness make it ideal for straightforward watch designs and first-time modders.()
NH34A: Adding GMT Functionality
The NH34A builds upon the NH35A by incorporating a GMT (Greenwich Mean Time) complication:
- Additional Function: Independent 24-hour GMT hand for tracking a second time zone.
- Design Considerations:
- Hand Stack Height: Slightly taller to accommodate the extra GMT hand, which may require a domed crystal for sufficient clearance.
- Dial Modification: The central post is wider (2.88mm compared to NH35A’s 2.05mm), necessitating enlargement of the dial’s center hole for compatibility.
The NH34A is perfect for those looking to add dual-time functionality to their watches, especially for travel or international communication purposes.()
Other Notable NH Movements for Modding
NH36A: Day-Date Functionality
An evolution of the NH35A, the NH36A includes both day and date complications:
- Functions: Hours, minutes, seconds, day, and date display.
- Use Case: Ideal for watches where a full calendar display is desired, such as tool or field watches.
NH38A: Clean Aesthetic
The NH38A omits the date complication for a cleaner dial appearance:
- Functions: Hours, minutes, and seconds.
- Use Case: Preferred for minimalist designs or watches with open-heart dials where symmetry is key.
NH70A: Skeletonized Design
The NH70A features a skeletonized design, showcasing the movement’s inner workings:()
- Functions: Hours, minutes, and seconds.
- Design: Skeletonized bridges and plates for visual appeal.
- Use Case: Perfect for statement pieces where the movement is a focal point.()
Choosing the Right Movement for Your Mod
When selecting a movement for your watch modification, consider the following:()
- Desired Complications: Do you need a date, day-date, or GMT function?
- Aesthetic Goals: Are you aiming for a clean dial, an open-heart design, or a skeletonized look?
- Technical Considerations: Ensure compatibility between the movement, dial, hands, and case, especially regarding hand stack height and dial hole diameter.
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