Chronograph Movements for Seiko Mods: A Look at VK Calibres

For years, Seiko modding has mostly focused on dive and dress builds using the trusty NH movements. And while Seiko’s VK mecha-quartz chronograph movements have been around for a while, they’ve never really taken off in the modding scene. But that might not be due to a lack of interest - we have a creeping suspicion that the real culprit is the lack of high-quality, purpose-built cases.

Without proper cases, building a VK-powered chronograph meant making compromises like settling for generic cases, dealing with bad fitment, or skipping the idea altogether. With our next case launch, we hope to change this. Our upcoming chronograph cases are designed specifically for the VK series, with high-standard finishing, tight tolerances, and compatibility tested in-house.

In other words: the wait is over. Modders can finally build chronos that not only look great but feel just as refined as they should. But before we get into the case specs, let’s take a closer look at the VK family of calibres and why they’re perfect for your next custom build.

The Different VK Movements

Source: Shirojira

If you’ve been dreaming of building your own chronograph Seiko mod, the Seiko VK series is your best bet. These mechaquartz movements are affordable, easy to work with, and give you that satisfying mechanical sweep without the high cost or stress of a full mechanical build. How are they different from each other though?

First up is the VK64, probably the most recognizable of the bunch. This movement powers a ton of well-known watches, from the Brew Retrograph to the Yema Rallygraf. It features a bi-compax layout with subdials at 3 and 9 o’clock: a 60-minute chronograph counter on the left and a 24-hour indicator on the right. The date sits cleanly at 6. What makes the VK64 unique is its lack of running seconds which is great if you’re going for a clean, vintage-inspired look or just don’t want too much dial clutter.

Source: 12 and 60

If you do want the full tri-compax experience, the VK63 will be your go-to. This movement adds a small seconds subdial at 6 o’clock, giving you constant movement on the dial, alongside a 60-minute chrono counter at 9 and a 24-hour subdial at 3. It also has a date tucked in at 4:30. It’s been used in popular builds like the Dan Henry 1963 and various Pagani Design chronographs, and its layout is ideal for racing-style mods or builds going for a Daytona vibe. 

Then there’s the VK67. While not as widely used, it still packs a lot of functionality: central chronograph seconds, a 60-minute counter, a 12-hour counter, small running seconds, and a date complication. It’s perfect for anyone wanting a chronograph that can actually track long time intervals. If you’re building a tool-style chrono and need the full feature set, the VK67 has you covered. Just keep in mind it’s slightly less common, so dial options might be more limited compared to the VK63 or VK64.

Source: Militado

Finally, we’ve got the VK61. It offers a symmetrical dial layout with the 60-minute chronograph subdial at 12 o’clock and running seconds at 6, along with a date window at 3. Unlike the VK63, it skips the 24-hour indicator, which can be a plus if you’re aiming for a cleaner, more minimal look. The VK61 isn’t as flashy as its siblings, but it’s rock-solid and especially great for budget-friendly mods or vintage-inspired designs that need balance and simplicity.

Why VK Movements Are Better than Mechanical

When it comes to modding, mechanical chronographs may sound cool but they’re not always the smartest choice. Some relatively accessible chronograph movements like the Seagull ST19 or Landerong mechanical chronograph are pricey, thick, and hard to build Seiko mods with. That’s where the Seiko VK mecha-quartz series comes in.

VK movements are way more accurate than most mechanical ones. While a mechanical chronograph can drift 10–15 seconds per day, VK movements stay within ±15 seconds per month. That kind of accuracy matters when you're actually planning to wear the watch every day and not just keep it on a shelf.

They’re also easier to build with. VKs are thinner (5.10mm), so they fit better in more case styles. You don’t need to deal with tricky stem heights or odd hand sizes as everything works with standard parts. Plus, even though they run on batteries, they still give you that smooth chronograph sweep that looks like a mechanical watch.

The bottom line is: if you want a reliable, great-looking chronograph that won’t give you a headache to build or maintain, VK movements are the way to go. They're perfect for modders who want performance, style, and less hassle in one package.

Upcoming namoki Chronograph Case

Building a custom chronograph used to be one of the biggest hurdles in Seiko modding. You’d either have to hack together parts from old Seiko donor cases, deal with poor dial alignment, or fight with fitment issues. That’s all about to change with our upcoming cases designed specifically for the VK chronograph series.

These new cases are designed from the ground up with VK chronograph movements in mind. Each case accepts dials sized between 30.5mm to 31.5mm, with a dial opening precisely measured at 29.5mm to perfectly showcase your chosen chrono layout. Size-wise, the case hits a sweet spot with a 39mm diameter, 46mm lug-to-lug, and a slim 8.1mm profile for the case itself. Once you add the boxed crystal and caseback, the total thickness comes to just 12.5mm.

Out of the box, you’re getting a pre-assembled case that includes a clear AR-coated boxed crystal, an integrated chapter ring, a brushed caseback, springbars, gaskets, a screw-down sterile crown, matching chrono pushers, and of course, that VK movement spacer. Everything is made to match our usual high standards for machining and finish.

We hope to see these cases provide another wave of creativity for Seiko modders! If you’re as excited as we are, be sure to subscribe to our newsletter and follow us on Instagram to be the first in line when our Chronograph case launches.

Happy modding!