Assemble Watches
What Parts Do I Need for a Seiko Mod?
A complete Seiko mod build requires: a case, movement (typically NH35 or NH36), dial, hands, bezel ring, bezel insert, crystal, caseback, and bracelet or strap. Each part has specific compatibility requirements with the others. Assemble Watches checks all of these as you plan your build.
- What is the minimum parts list for a Seiko mod?
- For a full build from parts, the minimum list is case, movement, dial, hands, crystal, crown, caseback, and either a strap or bracelet. Diver-style builds may also need a bezel ring, bezel insert, and chapter ring, unless those are built into the case. Many case bundles include several of these items, so read the bundle contents closely.
- What movement should I use for a Seiko mod?
- The NH35 is the standard choice for date-only Seiko mod builds because it is widely supported, affordable, and easy to source. The NH36 is the equivalent choice for day-date dials. Choose the movement after choosing the dial style, because the dial aperture decides whether date-only or day-date makes sense.
- What dial should I choose for an NH35 build?
- Choose a dial that explicitly lists NH35, NH36, or SKX compatibility and check whether it has a date window, day-date window, or no window. A typical SKX-style NH build uses a 28.5mm dial, but the exact case still matters. The dial also sets the design direction, so choose hands and bezel parts that match its tone.
- What tools do I need for a Seiko mod?
- For basic strap work, you need a decent spring bar tool. For dial and hand work, you need a caseback wrench, hand removal tools, hand setting tools, Rodico, a loupe, and a clean work surface. For crystal swaps, add a crystal press with suitable dies. Do not buy the cheapest version of every tool: bad tools scratch parts quickly.
- Where can I check all my Seiko mod parts are compatible before buying?
- Use the Assemble Watches builder to preview the parts together and catch major compatibility issues before ordering. It checks relationships such as movement-to-dial, case-to-bezel, case-to-bracelet, and other platform rules where catalog data is available. You should still confirm the final dimensions on the vendor listing before paying.