Dr. Ito's thorough analysis of mechanical watches!! Vol.11 - What is the difference between an overhaul and a partial service?

Good evening everyone!

This column talks about mechanical watches from an engineer's point of view. This is the 11th installment.

"The difference between overhaul and partial service"

I will be talking about this topic.

Mechanical watches are made up of a collection of parts, with at least tens and at most hundreds. Even the slightest problem can cause a malfunction, so regular maintenance is necessary.

What is performed there is an " overhaul (complete repair)" or "partial service (partial repair)" .

This time, we would like to explain questions such as, What is an "overhaul"? What is the difference between an "overhaul" and a "partial service"? Please read to the end!

"What is an overhaul?"

The word "overhaul" comes from the English word "OVERHAUL" and means disassembly, repair, and complete inspection . It refers to "the process of disassembling a mechanical product down to its individual components, cleaning and adjusting it, and then reassembling it to bring it closer to the performance of a new product." By the way, the word is used not only in the watch industry, but also in cars and musical instruments.

It is also often abbreviated to OH, and even people who aren't very knowledgeable about watches have probably seen it.

During a watch overhaul, the movement is disassembled and thoroughly cleaned and adjusted. The main steps are as follows:

1. Remove the movement from the case, and remove the hands and dial.

2. Disassemble each part and replace any damaged parts.

3. Clean all parts with a dedicated ultrasonic cleaner

4. Assemble and adjust while applying oil to the gears, etc.

5. Testing accuracy and water resistance

Most of the overhaul process is done manually by technicians, which shows that it requires skilled techniques and a long work time.

Why is an overhaul necessary?

The purpose of an overhaul is to prevent major breakdowns by replacing worn parts inside the watch.

Just like with humans, it is important for mechanical watches to have regular checkups to detect any problems early.

If the problem is merely at the initial stage, the watch can be restored to a healthy state by adjustment or replacement of minor parts, but if the problem is left untreated and the entire movement is damaged, it will be necessary to replace the main part called the base plate or the entire mechanism itself.

For this reason, it is recommended that most mechanical watches be overhauled every 5 to 10 years .

If you neglect an overhaul for many years, what will happen?

・Wear and damage to parts due to deterioration of lubricating oil

・Loss of waterproofing and rust due to deterioration of rubber gaskets

-Loss of accuracy

・Loss of power reserve

These problems occur.

One particular problem is the deterioration of lubricating oil. The gears of a mechanical watch operate smoothly when they are lubricated with oil, but after many years of use, the oil will run out and the gears will begin to wear out.

If this happens, the gear shafts and bearings may become worn down or the teeth may chip, which could result in expensive part replacement.

Difference from partial service

Did you know that there is a term called "partial service" in contrast to "overhaul"?

Some manufacturers call an overhaul a "complete service," which implies "all" or "thorough."

On the other hand, partial service means that maintenance is performed "partially" or "in part."

For example, if it has only been one year since your watch was overhauled but you are still experiencing symptoms such as the watch running slow or the calendar slowing down slightly when changing time, a partial repair can be performed to restore your watch to good condition.

However, if it has been more than five years since the last overhaul and you are experiencing symptoms such as "the accuracy of the watch is significantly poor" or "the calendar does not change", then an overhaul is necessary. ( *Some workshops do not accept partial services and may only handle overhauls. )

As you may have noticed, an overhaul is more time-consuming than a partial service, so of course it is more expensive. However, in terms of the difficulty of the work, a partial service can actually be more difficult.

For a technician, an "overhaul" is a task that can be "standardized" to a certain extent, but in the case of a partial service, the technician must identify the cause and determine the necessary work based on the condition of the watch and the nature of the malfunction.

In other words, it is difficult to perform partial service unless the technician has been through the overhaul process for many years and has a certain amount of experience.

Also, if any malfunction occurs during the warranty period, each manufacturer will likely have a veteran technician in charge of repairs who can identify the cause of the malfunction and provide feedback to the head office. Considering these factors, a "partial service" may be considered a more luxurious form of maintenance than an "overhaul."

By the way, you might think that if you only do a partial service, you can continue to use it, but a partial service only repairs the parts that are causing the breakdown, and does not lubricate other parts. So regular overhauls are still essential.

summary

What did you think?

Overhaul (complete repair) and partial service (partial repair). Just hearing the words, overhaul may seem like the more difficult option, but partial service has its own unique challenges, and I hope you can now see that the experience of the worker is important.

Even if you request a partial service, depending on the manufacturer's policy and the condition of the watch, you may only be able to have it overhauled. However, knowing the difference between the two is important to enjoying a fulfilling watch life.

We hope that this article has been useful to you and has piqued your interest in luxury watches! If you have any questions, please feel free to contact us directly and we will answer them thoroughly. We look forward to your visit and inquiries.

Look forward to the next one! See you next time!