Have you ever wondered why an automatic watch is called “automatic”?

The automatic winding rotor is one of the most groundbreaking inventions in watchmaking history. It is a self-winding mechanism that was invented by a Swiss watchmaker, Abraham-Louis Perrelet, in the 1770s. 


Source: Perrelet


He created a self-winding mechanism that featured a rotor that winds the mainspring in both directions which was then mainly used in pocket watches. 

At that time, a watch had to be wound manually for upwards of 15 minutes to operate for eight days. With the advent of the automatic winding rotor mechanism, the watch wearer’s movement itself became the way it was given energy. 

What is A Watch Rotor?

Automatic winding was introduced in mechanical wrist watches in the 20th century. As it could easily create energy for the watch, automatic winding became a standard in most mechanical watches.

The winding rotor is generally a half circle-shaped metal weight that is attached to the movement. Also known as the oscillating weight, this watch component swings through 360° thanks to the movement of the watch while worn on one’s wrist. 


Source: Caliber Corner


Through a series of gears, the rotor is connected and winds the mainspring as it turns, which supplies the watch with mechanical energy. The rotor also comes with a clutch which will disengage it from winding when the mainspring has been fully wound.

The quartz watch is a more efficient and accurate watch, but many watch enthusiasts think that this innovation sacrificed artistry for the sake of accuracy and functionality. For this reason, mechanical watches are still more valued than its more technologically advanced counterparts.

Making The Rotor Special 

While quartz watches are considered more accurate and efficient, the watch rotor and mechanical workings highlight the elegance and classic beauty of mechanical timepieces. 

Take, for example, the rotor found on the Audemars Piguet Royal Oak Equation of Time. It is a Skeletal rotor with intricate engravings that is truly worthy of the watch that it winds. The openwork also spells out the AP logo which is a wonderful detail that one may miss on the first look.


Source: Wrist Review


Another watch with a spotlight-stealing rotor is the Christiaan Van Der Klaauw Real Moon Joure Horizon, with a backside that is every millimeter as interesting as the front. The first thing that will catch your eye is the central gear made to look like the Sun, with the rotor featuring a rippling pattern to symbolize the sunrays. Also on the rotor are the moon and stars. A delight on the eyes!

If you like watch rotors, and want to know more about how to customize yours, you are in the right place! 

Why Should You Swap A Watch Rotor?

Automatic watches made a strong comeback recently as more and more watch lovers choose mechanical watches over quartz. Watch rotors aren’t generally a part of what people see in an automatic watch. They face the wrist, and in most cases, are covered by a caseback. 



For watch modders, the watch rotor can be an opportunity to further customize a watch. In addition to common watch mod parts such as the dial, or bezel, changing the rotor can make a watch mod even more unique. Like an easter egg to be seen on the rare times that you are looking at the back of a watch.

But, is it easy to do?

How To Swap Out Your Watch Rotor?

A Seiko watch is one of the easiest watches out there for watch mods. The rotor on most Seiko movements is simple to swap, and there are loads of caseback options to show off this mod. 

Common Seiko movements like the NH35 and NH36 don’t have fancy rotors, and you can very easily replace these parts with something that you like more. You will need a caseback remover for your watch to avoid scratches and damage.

In addition, you should have:

  • A screwdriver
  • Tweezers to lift the rotor once disengaged
  • A pegwood or finger cots to finely adjust or test the rotor once it has been reinserted into the movement
  • Rodico to clean your movement

Our upcoming toolkit contains all the tools mentioned above. ;)


Just remove the watch caseback, then take the rotor out from the movement, add the new one into the movement, and test if the rotor is engaging the gears correctly. 

Of course, these steps require your full attention, and every one must be done carefully. Here’s a more in-depth guide on how to swap out the watch rotor.

Necessary Part: A Display Caseback

A display caseback is used on a variety of timepieces, especially with automatic mechanical watches. You can see the mechanical movement operate with a glass caseback, and they are a must when you use a custom rotor. They are an original part on the newer Seiko 5 Sports watches, but SKX007 cases, both OEM and aftermarket, usually feature a full stainless steel caseback for better water resistance.


Get it here


Instead of using opaque metal to cover the back of the watch, a display caseback uses a piece of glass that is connected to a metal ring. With the glass in place, you can see both the movement, and your new custom rotor. If you’re not thinking of bringing your watch for a dive, it might be best to fit your watch with a sapphire display caseback instead!

Rotor Options for You

There are loads of custom movement rotors out there. Here at namokiMODS, we offer some great custom rotor choices for your next watch mod.



If you want to use an Eastern design, we have Great Wave rotors in four different finishes. For the classic Swiss look, we also have a Cote de Geneve rotor in both gold and steel.



The Great Wave rotors use the Japanese Seigaiha pattern, which was used to designate the sea on old maps. It looks great in the back of your watch, and don’t forget to pick up a display caseback too. 

Our Snowflake rotors, which feature a full, asymmetrical circle, were inspired by the skeletal rotor found on the Bell & Ross BR05. These watch mod parts would work perfectly in almost any design, and they are really something different that will set your mod apart from the rest! 

Doing A Rotor Swap!

It might seem like a new rotor isn’t a big deal, but if you add one to your next watch mod, you will see why so many modders use custom rotors. Here at namokiMODS, we offer an extensive selection of SKX007 parts, as well as loads of OEM Seiko spare parts for Seiko Mod Watches. 

With so many options for watch spare parts out there, make sure you deal with a supplier you can trust. Please take a look through our catalog, and think about all the options we offer for your watch modding or repair needs! 

September 03, 2022 — Jeremiah A

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