How to Mod Your Seiko Watch to Create the Seiko Nautilus

A watch is a valuable accessory because they are functional yet aesthetically pleasing. For this reason, all watch lovers get only the best watches for their collection, which are almost always from a luxury brand. While there are many luxury brands in the watchmaking industry, few can compare to the giant that is Seiko, which is a Japanese watch brand that has been around for more than 140 years.

Seiko’s longevity is a testament to its commitment to quality and innovative designs. What’s even better about Seiko is that the company encourages modding, which is a practice that allows wearers to customise and personalise their watches. Different builds suit this, but one of the best in recent years is the Seiko Nautilus, which combines classical watch design with a modern spin. To help you build this watch, we will guide you in this article.

What Do You Need?

Building a Seiko Nautilus requires certain mod parts. These include:

  • Flat Sapphire (comes with a free case)
  • NH35 hands
  • NH36 or NH35 Movement (depending on your dial)
  • Nautilus Compatible Bracelet
  • Nautilus Conversion Case
  • SKX007 Chapter Ring
  • Seiko Dial
  • SKX007 Crown
  • SKX007 Caseback

These parts are available in most Seiko parts stores and online retailers. Because of this, you may need to inquire about the availability of these parts. Some parts may also be sold separately, while others may be sold as part of a kit.

Choosing a Nautilus Case

First and foremost, you must decide on a Nautilus case. Many different colours and finishes are available, so you can choose the one that best fits your style. We suggest a two-tone black and silver Nautilus case, but you can also use a gold dial or a gold and silver two-tone Nautilus conversion case.

Choosing a Movement

When choosing a movement to use with a dial, you must consider whether or not the dial has a date window. If the dial has a date window, either an NH35 or NH36 movement can be used. However, if the dial does not have a date window, an NH38 movement is the best choice. If an NH35 or NH36 is used with a dateless dial, you may hear a clicking sound at midnight, referred to as a “phantom date change”.

To make a skeleton Nautilus watch, you will need an NH70 movement designed to be visible and a grey movement spacer to fit it in place.

Installing the Dial and Hands

Setting up the dial is a straightforward task. Two must be cut off if the dial has four feet. On the other hand, when the dial has no feet, special dial dots must be used instead. You must be careful when doing this because the slightest error can break it.

Likewise, installing watch hands is also easy and can be done according to personal preference. Buy NH35 hands, suitable for 28.5mm dials, to achieve a successful result. Choosing hands that complement the hour markers is vital to ensure all the parts fit together seamlessly.

Chapter Ring, Sapphire, and Crowns and Casebacks

The good news about installing these parts is that you can use standard SKX007 components, meaning you can get them in most watch parts stores. The chapter rings are an essential part of the watch, as they provide the frame and the reference points for the hands, markers, and other components.

Sapphire crystals are the most common type of watch crystal, and they come in various shapes and sizes. If you are making a customised watch, you can use a crystal with a different shape or size than the standard SKX007.

Crowns and case acks are the final pieces of the puzzle. They provide the finishing touches and keep the watch watertight. Make sure to purchase crowns and casebacks for the specific watch you are making, as they come in different sizes and shapes.

Choosing a Bracelet

The Seiko Nautilus Case is designed with a 20mm lug width and a distinct shape. This means that the standard SKX007 bracelets can not be used with it. Fortunately, some replacement bracelets will fit this watch case, including steel oysters and FKX-fitted straps.


The Seiko Nautilus is a quality customised watch designed for long-term and durable use. While building it won’t be easy, the effort will be worth it because you can get a unique timepiece. All that matters is getting your parts from reputable sources to ensure the best quality.

If you are looking for Seiko SKX mods, SeikoMods has what you need! We offer various selections to let you customise your watch for improved performance for affordable prices. Mail us today at to place an order!

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