Maintenance of IWC's popular pilot's watch. A 30-year-old watch and a technician come face to face

Yutaro Iizuka, a watchmaker at Chrono Theory Tokyo, explains the importance of watch repair and maintenance through actual work. This time, he focuses on IWC's popular pilot's watch, the Mark XII. As this series has been on the market for over 30 years, there are significant individual differences in the deterioration of consumable parts. This article is written from the perspective of what Iizuka thinks about when he carries out repairs.

Overhaul of the IWC Mark XII

　This time, I'm performing maintenance on an IWC Mark XII. In my previous articles, I've written about the difficulties I face when repairing watches. However, this time I'd like to take a slightly different perspective and delve a little deeper into what actually happened in the movement when a user experiences a problem, and what the technicians are thinking. To see what I did to the watch, please watch the video.

Maintenance begins with inspecting the watch

　Before we get to the maintenance, let's review what this watch is all about.

The reason it's called a masterpiece

　First of all, the movement used in the Mark XII is based on the Jaeger-LeCoultre Caliber 889. Since its founding in 1833, Jaeger-LeCoultre is said to have produced over 1200 highly accurate movements.

　These watches have been supplied to many luxury watch manufacturers. Jaeger-LeCoultre's watchmakers, who have created highly accurate and reliable machines, are known as "the watchmakers' watchmakers," and the watches they produce are called "the watchmakers' watches."

　This time, based on the Jaeger-LeCoultre Cal. 889, we have created a movement C that is typical of IWC.
This article will cover the maintenance of a watch that has been transformed into the al.884/2. A customer came to us with a problem: "I recently purchased a watch that is 8 minutes slow and I can hear a clicking sound when I wind it." Let's take a look at the process of repairing a watch that is about 30 years old.

The information obtained at the time of receipt determines 8% of the observation points during repairs

　When I picked up the watch, the first thing I noticed was a black substance on the crown. "What is this...?" When an engineer sees this, many thoughts cross their mind. Even when they are talking to a customer, their train of thought tends to be focused on that. They hold back, push it aside for a moment, and continue with the checking process.

　Just as the customer had said, the feel of the reel sliding smoothly through my hands when winding it up was like a click. "Hmm. I see, it looks quite difficult. I'll contact a few parts stores, and if I can't find the parts, I'll ask some friends, or maybe I should consider making one myself. Do I have that tool around?" Again, I put my thoughts on hold.

　Watches with tritium dials and hands are often replaced by alternative parts by manufacturers, as their characteristics can cause anxiety to users. For this reason, users who want to avoid replacement due to the appeal and rarity of tritium often ask their regular watch repair shop for help.

　When I receive a repair, I talk to the customer as much as time allows. Surprisingly, the customer often remembers things like how they purchased the product or if they experience any issues when using other features. I value this type of communication because I believe it is the first step in determining the quality of the repair.

　Because it has a solid case back, the only thing the customer could tell from this condition was that the crown was black. If the customer wasn't familiar with mechanical watches, the repair might have come later, requiring a lot of work and replacement parts.

A summary of the problems that occurred with the Mark XII

　Now, I would like to give a rough outline of how I deal with defects. There are many things that should be looked at in more detail, but I have omitted most of them.

　First, consider the possibility of poor waterproofing. Is the watch in a condition where it is suitable for a waterproof test? How do you open the back cover? Is it even OK to open it? You might wonder if it's necessary to think about such things, but these are some of the most basic and important factors.

　Even if we focus only on the waterproofing test, if a small crack in the crystal is overlooked, it is not impossible that the crystal could break under the pressure applied during the waterproofing test. Considering the risk of irreparable damage, such as the fragments damaging the dial or hands, it is easy to understand why they are so cautious.

　Observe carefully, think carefully, observe again, and devise a work order. Sometimes, not consulting with the customer before proceeding can lead to irreparable accidents. Since the work is full of risks, caution may be an important quality for a watchmaker. Some watches have the entire interior filled with special oil. The moment you open the back cover without thinking, something irreparable can happen.

　When a watchmaker encounters that moment of fear, he stops the movement for three seconds to confirm whether it is real or not. This is a true story. Some people, not me, need five seconds to confirm what is happening. Not me. No one wants to experience this feeling, but it is also true that in many cases it leads to growth as a watchmaker.

　I won't go into any more detail about accidents, as they can bring up traumatic memories. What I want to say here is that watchmakers, especially those in the general public, must always approach their watches with a sense of tension, knowing that the possibility of such trouble is close at hand. If there are skills required of watchmakers, perhaps the most important skill, even before dexterity, is "observation."

Regarding defective parts

　Let's take a look at the part that needed replacing this time. It's obvious when you compare it to a normal part. The tips of the gear teeth are gouged out. In other words, it's clear that the part is deformed (worn). As the mainspring is repeatedly wound, some of the shape has become deformed. This is thought to have caused the teeth to slip and disengage, which is what makes the noise you hear in your hand.

　When a technician finds a defective part like this, one thing they will surely consider is whether the part is available. But have you ever wondered what kind of movement your favorite watch uses and whether the parts are readily available?

　Roughly speaking, the following understanding is sufficient: parts for generic movements (other than in-house movements), generic gaskets, and circular crystals are easy to obtain. However, parts for in-house movements, specially shaped gaskets, and crystals are harder to obtain, especially for newer models.

　In-house manufactured movement parts with a long history are occasionally offered at overseas auctions, but even these opportunities are becoming less frequent and prices are rising.

　Regardless of whether parts are available or not, when a malfunctioning part is discovered, how to resolve the issue is one factor that increases the difficulty of repairs. When it comes to in-house manufactured movements, this is a test of a watchmaker's potential. Aside from careful consideration of disassembly procedures, most of the time when making a quote is focused on the malfunctioning part.

　The Jaeger-LeCoultre-based movement, Cal. 884/2, is no exception, and parts are difficult to obtain. It's safe to say that parts for Jaeger-LeCoultre watches that promise permanent repairs are generally difficult to obtain. In this case, we were able to find one thanks to the history and popularity of the movement. In case we couldn't find it, we were also preparing to manufacture original parts. After discussing the price of the parts and options for the work with the customer, we decided to purchase the parts.

　If you're a vintage or antique watch enthusiast and have read this far, I would especially like you to find out what movement is installed in your watch. It's a good idea to consult your local watch shop about the difficulty of obtaining parts. The investigation may take some time, but it's a good idea to consult with them and have them inspect your watch. I'm sure it will be helpful when considering maintenance.

There's a clicking sound when I wind it up, what causes it?

　Now let's take a closer look at the abnormality in the watch. What does it mean to hear an abnormal noise? An abnormal noise coming from the crown refers to a non-periodic sound that is heard by the hand when operating the watch. In this case, the abnormal noise is when winding the watch, and an irregular clicking sound is heard by the hand.

　To understand why the tooth deformation seen above occurs, we need to understand the behavior of this gear. This part is called the winding pinion, and is one of the parts involved in winding. It is one of the few gears that rotates in the same direction as the crown that we operate. A distinctive feature of this part is that it is 90 degrees to the gear it meshes with, meaning that the rotation axes of the two gears form a right angle.

　This special force transmission places more strain on the teeth than the meshing of gears arranged on the same plane that we typically imagine. Furthermore, the rotation is caused by the force of the hand. This has a huge impact on the teeth, which are less than 1mm apart. It is easy to understand why deformation occurs after years of use.

　However, it is extremely difficult to create special gears that reduce the load of 90-degree meshing in a watch-sized movement that does not have a thick movement, due to the balance between technology and cost. It seems that there are an increasing number of watches that have been designed with ingenious tooth tips and shapes, but this only serves to reduce the rate at which damage accumulates.

　This damage is difficult to avoid, so what can users do to reduce the risk of deformation and noise?

　That is, "Don't wind up a watch you're not using." The movement of a mechanical watch is fascinating to anyone who likes machines, but please avoid winding it every day if you're not using it. Running a watch every day means that all the gears are working at full power, which causes the metal on the gear shafts to fatigue and the oil to dry up. For this reason, most of the watches on Chronotheory's shelves are stopped.

　If you are starting to use an automatic watch from a stopped state, it is best to wind it minimally using the crown (starting from about 10 to 15 times, increasing the number depending on your activity level and adapting to your lifestyle).

Packing is essential for waterproofing

　The next thing I want to talk about is the gasket. Gaskets are essential for a waterproof watch and play a major role in ensuring the watch can be used for a long period of time. Another characteristic of gaskets is that they are often replaced during maintenance.

The role of packing

　Let's take another look at the black object near the crown. In fact, it is a gasket. It is a gasket that had not been replaced for a long time and has now become completely distorted. When Iizuka saw this at the reception desk, he searched his brain for the appropriate size gasket in stock, while also wondering how he would clean the inside of the crown thoroughly and whether it was even possible to replace it. It is not something you should be thinking about at the reception desk, but the incident made him think about it.

　The gasket is made of a material called nitrile rubber, which is oil-resistant, heat-resistant, and abrasion-resistant. Its resistance to friction, despite being rubber, is particularly appreciated in watches. The gasket is constantly subject to friction inside the crown, which is operated almost daily. This can quickly cause the watch to lose its water resistance. I imagine this was a major problem for manufacturers before nitrile rubber was available.

Deterioration process

　However excellent the gasket is, it is inevitable that it will deteriorate over time. No matter how excellent the waterproof structure of a watch is, if the gasket deteriorates, the waterproof function will no longer work.

　From here on, I would like to share my personal speculation on gasket deterioration.

　The packing begins to deteriorate when it loses its elasticity. This can last for about three years depending on the watch's construction. Packing, which works best when crushed, gradually loses its airtightness.

　When the gasket loses all its elasticity, it will break easily when pulled. Just like an old rubber band. In the final stage, the gasket will melt. Isn't this also the same as a rubber band? It will not have a smooth consistency like ice cream, but will become thick and sticky, and will stick to the metal. In this case, the gasket had reached the maximum deterioration stage.

交換の必要性

　Once the watch has reached the most severe stage of deterioration, it is extremely time-consuming to remove the stains. Of course, they cannot be removed with just an ultrasonic cleaner. They must be removed by scrubbing or, depending on the conditions, by using chemicals. In places like the gasket inside the crown, which are difficult to reach with your hands or even with cleaning tools, the removal process can be quite painful.

　It is impossible to say exactly when the gasket will become like this, as it depends on the environment in which the watch is placed.

　Manufacturers and repair shops will check the condition of the gasket and recommend replacing it. In some cases, crown replacement is required for manufacturer maintenance. Replacing the crown gasket, especially removing it from the crown, can be as difficult as trying to retrieve a 1 yen bill that has fallen into the gap behind a stationary dresser.

　Due to the difficulty and time required for the procedure, the manufacturer's suggested crown replacement is a very rational and efficient method.

Movement's impressive points

Switching rocker and movement finishing

　Finally, I would like to conclude this lengthy article by introducing some of the points that I found amazing and impressive.

　It seems that some Jaeger-LeCoultre movements use rubies in the switching rocker wheels, while others do not. This particular example uses rubies, making it clear that it is more robust. Unlike Jaeger-LeCoultre's finish, it does not have a flashy impression, but its simple finish gives it a powerful look.

　This matches the overall impression of the watch, and I think some people will find this part appealing. You can see Jaeger-LeCoultre's finishing by searching for "LeCoultre 889 movement," so it's interesting to compare the two and see how different the impressions are.

　We have also captured the movement of the switching rocker on video, so please take a look at the link at the beginning.

To the end

　I don't usually work while being watched, much less filmed, so even during the second shoot, I felt a different kind of tension than usual.

　I thought that some people might become concerned about my maintenance skills after seeing how I handled the screwdriver and the trembling in my hands. However, if it could improve the quality of the maintenance even a little, it would fit with the purpose of writing the article, so I decided to publish the video without any embarrassment (it goes without saying that the video itself is excellent, and it's about my skills).

　Although the video is just under 30 minutes long, it took about three days to shoot. We always promised to go out to dinner on the day we finished filming, but we were so tired that we still haven't kept that promise. That's how seriously we took filming and the work.

　I also constantly reflect on my writing. I write, revise, and rewrite many times. This back-and-forth process reminds me of repairing or making a watch, so I have to be more careful and it takes longer.

　It may be difficult to take photos and write articles at the same time for a while (blank stare), but I hope that I can continue to write articles little by little in the future so that users can have a clearer understanding of maintenance.

　Finally, I would like to express my deepest gratitude to the customers who allowed me to photograph the rotating gears and the clocks.

Author profile

Yutaro Iizuka
A watchmaker currently employed at Chronotheory. While studying at Hiko Mizuno College of Jewelry, he participated in the 2018 Walter Lange Watchmaking Excellence Award. The assignment from A. Lange & Söhne was to "create a watch with an acoustic notification function." He created a bimetal thermometer that would sound when the temperature exceeded a certain level. The gongs were made from sanukite, a mineral found in Kagawa Prefecture and used in lithophones. The watch he created won an award. After graduating, he worked at a repair company before taking up his current position. His Twitter account is "@khronos_." He is a zombie master and a member of the GPHG Academy.