A NHXX movement is the beating heart of modified Seiko watches, this page covers a number of the other calibres included within Seiko mods. The calibres (movements) included in this guide are the NH34, NH35 and NH36. Seikomodder.com have used NHXX in places to signify any one of these movements.

These varying calibres came to the market from 2016, the most recent release being the NH34 with the 24-hour, or GMT hand, complication. They are built on the base calibre of the 4R35 which came into production in 2011. It is argued by many that this movement rivals the Swiss movements in lower priced Swiss watches, on durability and accuracy, as well as long term operation.

Seikomodder.com provide further information on each individuals movements operations, but suffice to say, the complications vary and there are options; date, day/date, and 24-hour complications are contained within this guide. All of these movements have complications.

The Cal. NHXX Overview and Specifications:

The Cal. NHXX is a Japanese movement produced by Seiko Instruments Inc. aka SII, Time Module Inc. aka TMI). It beats at 21,600 beats per hour. This means the second hands moves six times per second to create the sweeping movement.

The tech data suggests that, worn daily for 8-10 hours, and at a temperature range of between 5°C and 35°C, the Cal. NHXX (movement) has an accuracy of +45 and -35 seconds per day. In practice, this is very far from the mark at these movements can be regulated to be more precise.

The movement has a number of features such as ‘hand-winding’, useful if your wear watches in rotation. It also features hacking of the second hands, effectively stopping the second hand so you can synchronise watches like you are in an 80’s actions movie! Operational instructions will follow.

Tech Spec NHXX Movement

Movement TypeAutomatic, self-winding mechanical
Casing Diameter29.36mm
Vibrations Per Hour21,600 bph
Lift Angle53 degrees
Shock SystemDiashock
Power Reserve41 hours
Rotor DirectionBi-directional winding (Magic Lever)

Cal NHXX Winding System

This movement features automatic winding with the manual winding mechanism.

Time Display on the Cal. NH34 (Movement)

The Cal. NH34 movement uses a four hand display located in the in the centre of the dial It also includes a date complication.

Time Display on the Cal. NH35 and NH36 (Movement)

The Cal. NH35 and NH36 movement uses a three hand display located in the in the centre of the dial. They also include a day complication, NH35 and a day/date complication, NH36.

If you’ve found this guide helpful, be sure to explore our collection of other informative guides at seikomodder.com. We offer a wealth of resources to assist you in your modding journey.