Dr. Ito's thorough analysis of mechanical watches!! Vol.30 ~ How to properly wind the mainspring

Good evening, everyone!

This column, where I discuss mechanical watches from an engineer's perspective, is now in its 30th installment. This time, our topic will be:

"How to Properly Wind a Mainspring"

Let's dive into that.

Winding the mainspring is an indispensable task for mechanical watches. Mechanical watches are broadly divided into two types: "manual-wind" and "automatic." This time, I will explain the common points that must be observed when winding the mainspring for both types.

The Power Source of Mechanical Watches

First, I'll briefly introduce how a mechanical watch works.

The power source for all mechanical watches is the "mainspring." The watch operates by utilizing the force of the wound mainspring as it unwinds. In other words, the mainspring is an indispensable component for all mechanical watches.

For example, consider a toy doll that walks for a short time after being wound up. It moves using the energy released as the wound mainspring unwinds. However, since there is no mechanism to control the unwinding force of the mainspring, it quickly unwinds completely and stops.

Mechanical watches are equipped with a "regulating mechanism" that adjusts the unwinding force of the mainspring to a constant interval after it has been wound. This mechanism vibrates like a pendulum at regular intervals, allowing the watch to tell accurate time. The regulated power of the unwinding mainspring is then transmitted to the gear train, which drives the hour, minute, and second hands.

Differences Between Manual-Wind and Automatic Watches

So, what exactly is an automatic watch? It's a wristwatch where the mainspring is automatically wound by the movement of the wearer's arm. The movement of an automatic watch is equipped with a rotor (oscillating weight). When the wearer moves their arm, gravity causes the rotor to spin, which then winds the mainspring.

If worn daily, it is unlikely to stop, and generally, manual winding via the crown is unnecessary. This benefit is significant for those who find manual winding inconvenient.

However, for individuals with sedentary jobs who don't move their arms much, or those who rotate between multiple watches, supplementary manual winding may occasionally be necessary.

Conceptually, it's like a manual-wind watch with an automatic winding mechanism added, so the basic structure doesn't change significantly.

Recommended Winding Method

Previously, on our YouTube channel "COMMIT TV," we introduced the correct way to wind a manual-wind watch, and at that time, we recommended the method of "slowly oscillating while keeping your finger on the crown."

This method has the advantage of naturally leading to a slow and careful winding process, but it is somewhat less efficient in terms of winding speed.

Therefore, this time, we will introduce the "slowly wind in one direction" method as a recommended winding technique for various mechanical watches, whether manual-wind or automatic.

Advantages of Winding in One Direction

・Power is efficiently transmitted to the mainspring.

The mainspring is designed to be wound in only one direction (typically when the crown is turned towards the 12 o'clock position); turning the crown in the opposite direction will cause it to free-spin. With back-and-forth winding, unnecessary movement occurs before the disengaged gears re-mesh, which can reduce winding efficiency.

・Slow winding reduces stress on internal parts.

Winding too quickly can put stress on internal components, especially the winding stem and click, risking breakage. However, if you make an effort to operate it slowly and carefully, you can avoid stressing the internal parts.

In automatic watches, specifically, the gears of the automatic winding mechanism also rotate when you hand-wind. Therefore, repeatedly winding too quickly or excessively can lead to needing an overhaul sooner. Please be particularly careful to wind slowly and gently.

The idea is to gently remove your finger from the crown, confirming that the click is receiving the repulsive force of the wound mainspring as it tries to unwind.

Summary

What did you think?

Even for something as simple as hand-winding, imagining the movement of the internal components and winding accordingly can reduce the burden on your watch, so I hope you find this helpful. I believe this content will be easier to understand through video than text, so I plan to introduce it on "COMMIT TV" in the near future.

I hope this article provides valuable information for everyone and sparks even a little more interest in luxury watches! Also, if you have any questions, please feel free to ask directly, and we will be happy to answer them thoroughly. We look forward to your visit or inquiry.

Stay tuned for the next installment! See you then!