Seiko 6R15: specifications and comparison

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Today we’re going to talk about the Seiko 6R15, one of the most widely used mechanical movements by the Japanese company today, along with other mechanisms like the 4R35 and 4R36.

Although 6R35 has better finishes and some higher quality components, it’s usually found in higher range mechanical watches.

An automatic movement that has undergone numerous revisions and that also serves as the basis for the manufacture of many other calibers, which can lead to confusion.

Therefore, in this post we will give a complete overview of all the characteristics of the Seiko 6R15, consider the different versions and compare it to other calibers to determine its quality.

✚ Seiko 6R15 datasheet

Manufacturer Seiko
origin Japan
model 6R15
Publishing year 2005
Move Automatically
Jewellery 23/24
Vibration frequency 21,600 vph
Energy reserve 50 hours
Dimensions 27.4mm x 5.25mm (diameter x depth)
precision +25 ~ -15 seconds / day
properties Hours, minutes and seconds on central hands and date
Stop seconds (hacking) And
Remonte manual And

✚ 6R15 in detail

The Seiko 6R15 is another design derived from the famous 7S36, a very reliable movement that is used in many of the brand’s watches but is already a few years old.Caliber 6r15 Seiko Sumo

For this reason, the 6R15 joined the family in 2005, a better crafted caliber with manual winding and a second stop, functions that the 7S36 lacked.

Precisely because of the finishes and components used in the Seiko 6R15, it’s considered a premium movement, and it’s generally used in upper-middle-range watches like the Seiko Prospex.

On a technical level, we have an automatic bidirectional rotor mechanism based on the “Magic Lever” system from Seiko and the Diashock shock protection.

Hence, we have a very efficient movement because it can charge energy in both directions and has a high resistance to shock and magnetism.

Compared to other cheaper calibers, the 6R15 mounts a Spron 510 main spring, a material that Seiko uses to achieve a higher power reserve.

While the 6R15 beats at 21,600 vph, a lower rate than other high-end calibers, it can run for years with little maintenance.

This mechanism is set using the Etachron system, a regulator that makes it easier to manipulate the spring and thus enables greater precision in experienced hands.

Finally, depending on the version, the number of jewels is 23 or 24, as it is a movement that has undergone numerous revisions.

➤ Accuracy

In terms of precision, Seiko reports a not inconsiderable + 25 / -15 seconds per day, a range that far surpasses other movements of the company.

The precision ranges must be understood as a classification in which the manufacturers localize their movements, which are more and more precise in practice.

In fact, there are many users of the 6R15 who manage to achieve values ​​under + -5 seconds. Diaries with a good fit.

➤ Power reserve

One of the strengths of the 6R15 is its power reserve, as it reaches 50 hours of operation when the mechanism is fully utilized.

This puts it above other popular movements by the brand like the 4R36 or the 7S36, both of which are derived.

Since it is an automatic watch, the maximum load can be achieved simply by wearing it, but also by hand winding. The maximum load is achieved by turning the crown approximately 50 times.

➤ Watches that use it

The 6R15 is a movement that many Seiko dress watches and also some divers of the brand use, all in the medium / high range.

For example, we can see it in many divers in the Prospex series and in some Seiko Sumo, as well as in the famous Spirit (SARB) and Alpinist models.

These are some of the most famous clocks with the above mechanism that are readily available right now:

✚ Seiko 6R15A, 6R15B, 6R15C, 6R15D …

The letters indicate different versions of the same movement. The first was the 6R15A and then the B, C and D followed with various changes that added improvements and solved problems.

That is why there are 6R15 movements with 23 and 24 jewels. The first versions had 23 while the most recent are made at 24.

It should also be noted that due to the added changes, not all components are interchangeable between versions.

✚ 6R15 as the basic caliber

The 6R15 serves as the basis for many other movements that add complications like a power reserve indicator and other subdials with the days of the week and date in different positions.

These are the calibers 6R20, 6R21, 6R24 and 6R27. They all strike at 28,800 vph (compared to 21,600 vph on the 6R15), but their power reserve is reduced from 50 to 45 hours.

They also have a greater number of jewels to adapt their operation to the new complications.

✚ Seiko NE15 versus 6R15

seiko ne15

The NE15 is none other than the version of the 6R15 that Seiko makes for other brands, and as you can see in the table, they are practically identical.

Like the Seiko NH35, the NE15 doesn’t have the branding printed anywhere, but the logo of Seiko Instruments Inc (SII), a division of the company responsible for manufacturing it.

model 6R15 NE15
Move Automatically Automatically
Jewellery 23/24 24
Vibration frequency 21,600 vph 21,600 vph
Energy reserve 50 hours 50 hours
Dimensions 27.40 x 5.25 mm 27.40 x 5.32 mm
precision -15 ~ +25 s / day -15 ~ +25 s / day
Stop seconds And And
Remonte manual And And

✚ Seiko 6R15 versus 6R35

The main difference between these two movements is in the power reserve, which is much higher on the 6R35. Otherwise, as you can see from the table, they are very similar.

The caliber 6R35 is considered an update of the 6R15 and has only been on the market for a year. The first watches with this movement were presented at Baselworld 2019.

model 6R15 6R35
Move Automatically Automatically
Jewellery 23/24 24
Vibration frequency 21,600 vph 21,600 vph
Energy reserve 50 hours 70 hours
Dimensions 27.40 x 5.25 mm 27.40 x 5.25 mm
precision -15 ~ +25 s / day -15 ~ +25 s / day
Stop seconds And And
Remonte manual And And

✚ Seiko 6R15 versus 7S26

Seiko 7S36 caliber

There are many, many differences between these two mechanisms, both in precision and in power reserve and functions.

Compared to the 6R15, the Seiko 7S26 is less precise, has 9 hours less power reserve and does not have the coveted functions for second stop and manual lifting.

It should also be noted that the 7S26 is a cheaper and older mechanism. Though out of date, it is still one of the brand’s most trusted and reputable movements.

model 6R15 7S26
Move Automatically Automatically
Jewellery 23/24 21st
Vibration frequency 21,600 vph 21,600 vph
Energy reserve 50 hours 41 hours
Dimensions 27.40 x 5.25 mm 27.40 x 4.8 mm
precision -15 ~ +25 s / day -35 ~ +45 sec / day
Stop seconds And No
Remonte manual And No

✚ Seiko 6R15 versus 4R35 / 6

Seiko 4R35 caliber watch

While the Seiko 4R35 is a bit more modern, the 6R15 is part of a higher range but is mounted on more expensive watches and, as you can see, has better specifications too.

The 6R15 is better processed and has higher quality components such as the Spron 510 spring compared to the Spron 110 with the 4R35.

Thanks to this, it can offer significantly higher precision and a power reserve that provides an additional 10 hours of operation.

The Seiko 4R36 is a 4R35 to which the days of the week have been added together with the date and have the same specifications. Hence what has been said for one also applies to the other.

model 6R15 4R35
Move Automatically Automatically
Jewellery 23/24 23
Vibration frequency 21,600 vph 21,600 vph
Energy reserve 50 hours 40 hours
Dimensions 27.40 x 5.25 mm 27.40 x 5.32 mm
precision -15 ~ +25 s / day -35 ~ +45 s / day
Stop seconds And And
Remonte manual And And

✚ Seiko 6R15 versus ETA 2824-2

ETA 2824 on watch

To say that the 6R15 is Seiko’s alternative to the well-known Swiss caliber ETA 2824 may be a bit presumptuous, but it is certainly a great move and can withstand it in some ways.

For example, it has a greater reserve of energy and, if properly adjusted, can be very accurate. Another thing is that it is able to maintain these values ​​over time.

In addition, due to its lower vibration frequency, the 6R15 requires much less maintenance than the ETA 2824, although the second hand does not move with the same smoothness.

model 6R15 ETA 2824
Move Automatically Automatically
Jewellery 23/24 25th
Vibration frequency 21,600 vph 28,800 vph
Energy reserve 50 hours 38 hours
Dimensions 27.40 x 5.25 mm 25.6 x 4.6 mm
precision -15 ~ +25 s / day + -12 / + -7 / + -4 sec. Day
Stop seconds And And
Remonte manual And And

✚ Time and date setting

As with most current mechanical movements, the crown allows you to make all the necessary adjustments and wind the watch. That’s how it’s done:

  • Hour: Pull the crown out to the second click (two clicks out), then rotate it in any direction (clockwise or counterclockwise) to move the hands to the desired position.
  • Date: Pull the crown out to the first click (1 click out). Turn counterclockwise to set the date to the correct position.
  • Remonte manual: Turn the crown clockwise without removing it. The full mechanism load is obtained with approximately 50 revolutions.

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Last update of the links and pictures on 2021-02-03. Prices and availability may differ from the prices published on Amazon.

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