Dr. Ito's thorough analysis of mechanical watches!!

Good evening, everyone!

I'm Ito, an appraiser and watch repair technician at Commit Ginza.

I worked for 20 years as a watch repair technician for a famous brand, but by chance, I started my career as an appraiser at Commit Ginza. This time, I decided to create this article in the hope of sharing information that is not commonly known, such as explanations of movements, how to use complicated watches, and daily care tips, utilizing my years of experience as a technician. I will also be sharing insider information that only a technician would know, so please enjoy reading it!

Now, for the memorable first installment:

"【Rolex】"Cal.31 series" vs. "Cal.32 series" - Which is better?"

I'd like to discuss this topic.

The "Cal.31 series" movement, which began with the "Cal.3155" installed in the "Day-Date" in 1988 and ended its long active life with the "Cal.3131" installed in the "Milgauss" "Ref.116400GV".

On the other hand, the "Cal.32 series" movement, which is now nine years old since its debut in 2015 and is installed in various current models, is entering its prime.

This time, I would like to compare these two movements from a technician's perspective! Please enjoy it to the end!

Comparison of "Cal.31 series" and "Cal.32 series"

As many of you know, both the "Cal.31 series" and "Cal.32 series" are excellent movements, with the former boasting the legendary "Cal.3135" and the latter the "Cal.3255". We have covered these in detail in many other articles on our site, so this time, I will omit the basic specifications and features and instead focus on their "weaknesses," which are rarely discussed.

Weaknesses of "Cal.31 series"

While the "Cal.31 series" is often lauded as a masterpiece, one of its few weaknesses is that the crown occasionally becomes difficult to pull out. This occurs when the teeth of the gears inside the watch collide when the crown is pulled out.

Normally, even if it gets caught once, re-pulling the crown usually allows it to operate normally. However, the "Cal.31 series" has a slightly more complex structure in this area, and there are cases where the problem does not improve no matter how many times the crown is re-pulled. When this happens, it needs to be disassembled and adjusted, so it can be considered its only weakness.

Incidentally, it is worth noting that the problem of the crown being unable to be pulled out rarely occurs in the "Cal.3130," "Cal.3131," and "Cal.3132" movements, which are installed in non-date models.

Weaknesses of "Cal.32 series"

The "Cal.32 series" addresses the weakness of the "Cal.31 series" by modifying the crown mechanism, virtually eliminating the problem of the crown becoming difficult to pull out. This is indeed a testament to Rolex's excellence. In addition, improvements include an extended power reserve from approximately 48 hours to 70 hours, and the adoption of ball bearings for the rotor of the automatic winding mechanism. Hearing this, one might think the "Cal.32 series" is a complete victory, but it also has its weaknesses.

That is, it tends to run slow.

Originally, Rolex watches were known for their extremely high precision, and currently, only watches that meet the strict inspection criteria of Rolex's unique Superlative Chronometer certification, with a daily variation of ±2 seconds when cased, are shipped. However, when precision is pursued to this extent, even the slightest change in accuracy can have a significant impact, leading to a delay of several seconds.

To elaborate, it is thought that due to improved design and machining precision, there is not only less play (gap) between components, but also a coating treatment to prevent oil dispersion further reduces play, which may increase friction between components.

This is likely a very slight difference, perhaps a few hundredths of a millimeter, but it still affects performance, which once again highlights the delicate nature of mechanical watches. However, as expected from Rolex, they are constantly making improvements, and from my personal experience, I feel that the frequency of "Cal.32 series" watches running slow has decreased.

Conclusion

The "Cal.31 series" has a weakness in the crown, which is relatively infrequently used in automatic watches, whereas the "Cal.32 series" has a concern regarding "accuracy," which is the most crucial aspect of a watch. I think the "Cal.32 series" is slightly at a disadvantage.

Seeking high precision and eliminating too much play (tolerance) can lead to problems... Mechanical watches and humans are the same. (laughs)

*This is solely my personal opinion.

Summary

This time, as I reviewed and compared the "Cal.31 series" and "Cal.32 series," I realized that both are excellent movements with only minor weaknesses that could be considered "if I had to pick one."

Also, I may have caused some anxiety by pointing out their weaknesses, but I believe it is important to be honest. These issues are not frequent occurrences, and they can be sufficiently improved through maintenance, so please rest assured.

I hope this article provides useful information and sparks even a little interest in luxury watches! I'll see you next time!