The NH35A movement is a reliable and affordable automatic movement widely used in various watch brands. While it’s known for its accuracy, there may come a time when you need to fine-tune its performance. Learning how to adjust NH35A movement can be a valuable skill for watch enthusiasts and professionals alike. In this step-by-step tutorial, we will guide you through the process of adjusting the NH35A movement to achieve optimal accuracy and performance.
Understanding the NH35A Movement
Before delving into the adjustment process, it’s crucial to have a basic understanding of the NH35A movement. Manufactured by the Japanese company TMI (Time Module Inc.), this movement is often used in affordable and mid-range mechanical watches. It’s a self-winding automatic movement, renowned for its robustness and reliability. The NH35A operates at 21,600 vibrations per hour (VPH) and has a power reserve of approximately 41 hours. While it’s generally accurate, there are times when you may need to fine-tune its timekeeping capabilities.
Gather Your Tools
To begin the adjustment process, you will need a few essential tools:
1. Case Back Opener: This tool is required to open the watch case back and access the movement.
2. Hand Remover: A hand remover is essential for gently removing the watch hands without damaging the dial or movement.
3. Hand Setting Tools: You’ll need tools for setting the watch hands accurately.
4. Tweezers: Tweezers are used for delicate handling of watch components.
5. Timegrapher: A timegrapher is a crucial tool for measuring the watch’s performance.
6. Screwdrivers: You’ll need screwdrivers for removing the movement from the case, if necessary.
Ensure you have these tools ready before you begin the adjustment process.
Setting Up the Watch
Before you can adjust the NH35A movement, you need to set up your workspace properly. Find a clean and well-lit area to work in. A clean workspace is essential to prevent dust and debris from interfering with the movement. Ensure you have a soft and clean surface to protect the watch’s crystal and case from scratches.
Step 1: Opening the Case Back
To access the NH35A movement, you’ll need to open the case back. Use the case back opener to carefully remove the case back without applying excessive force. Take your time to avoid scratching the case or damaging the gasket, which ensures the watch’s water resistance.
Step 2: Identifying the Regulator
Once you have access to the movement, locate the regulator. The regulator is a small lever that can be used to adjust the balance wheel’s speed and, consequently, the watch’s timekeeping accuracy. It is typically marked with “REG” on the movement.
Step 3: How to Adjust NH35A Movement – Slowing Down or Speeding Up
To adjust the NH35A movement’s accuracy, you can either slow it down or speed it up. Use a precision screwdriver to make the necessary adjustments to the regulator. Turning the regulator screw clockwise will slow down the movement, while turning it counterclockwise will speed it up. Make very small adjustments, as even a slight turn can have a noticeable impact on accuracy. Repeatedly check the watch’s performance with a timegrapher to gauge the effect of your adjustments.
Step 4: Check for Rate Errors
Once you’ve made your initial adjustments, use the timegrapher to check the rate errors of the NH35A movement. Rate errors refer to the variance in timekeeping over a specific period. It’s essential to check the watch’s performance in multiple positions, such as dial up, crown down, and crown left or right, to ensure that it maintains consistent accuracy.
Step 5: Fine-Tune Your Adjustments
After checking the rate errors, you may need to fine-tune your adjustments. This process can be iterative, as small changes can affect the movement’s performance differently in various positions. Continue making incremental adjustments and rechecking the watch’s accuracy until you achieve the desired timekeeping performance.
Step 6: Reassembling the Watch
Once you are satisfied with the watch’s accuracy, carefully reassemble the watch. Ensure that the gasket and case back are properly sealed to maintain water resistance. Use the hand setting tools to place the watch hands back in their correct positions. Take your time during this process to avoid damaging the hands or dial.
Step 7: Monitoring Performance
After reassembling the watch, it’s crucial to monitor its performance over the next few days. This will help you confirm that your adjustments have resulted in improved accuracy. Use a timegrapher to assess its rate errors and make further adjustments if necessary.
Conclusion
Learning how to adjust NH35A movement can be a rewarding endeavor for watch enthusiasts and professionals. With the right tools and a careful, patient approach, you can enhance the accuracy of your NH35A-equipped timepiece. By understanding the basics of the NH35A movement and following the step-by-step tutorial provided, you can enjoy the satisfaction of owning a watch that keeps time with precision. Keep in mind that practice makes perfect, and as you gain experience, you’ll become more adept at fine-tuning this reliable automatic movement.
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