Assemble Watches
Watch Modding FAQ
Common questions about Seiko watch modding, parts, tools, and the Assemble Watches builder. New here? Start with the Beginner's Guide.
Getting Started
- How do I mod a Seiko watch?
- Start simple: swap the strap using a spring bar tool. From there, work up the ladder: bezel insert swap, crystal swap, then dial and hand work. Each step requires slightly more tools and care. The Assemble Watches Beginner's Guide covers the full progression with tool requirements at each stage.
- What is the easiest Seiko mod for a beginner?
- A strap or bracelet swap. It requires only a spring bar tool (around £8), takes under 10 minutes, and there's almost nothing that can go wrong. A bezel insert swap is the next step up, genuinely a 15-minute job once you've done it once.
- Which Seiko should I start modding?
- The SKX007 (discontinued, buy used) or any SRPD / 5KX variant (current production). Both have enormous aftermarket parts libraries. Buy the cheapest example you can find in decent shape for your first mod. Don't start with your nicest watch.
- How much does a Seiko mod cost?
- A basic mod (strap or bezel swap) costs under £30 including the tool. A full dial and hand build with a sapphire crystal runs £80–£150 in parts. A complete build from a donor case including movement, dial, hands, bezel, and bracelet typically ranges from £150–£300 depending on part quality.
- Do I need watchmaking experience to mod a Seiko?
- No. Strap swaps, bezel inserts, and even crystal swaps require no prior experience, just patience and the right tools. Dial and hand swaps require more care (dust control, compatibility checks) but are within reach for a careful first-timer. Movement swaps are the most involved but still doable at home with research.
Parts & Compatibility
- What parts do I need for an NH35 build?
- At minimum: a case, dial, hands, movement (NH35), crystal, bezel, bezel insert, and bracelet or strap. Each part has compatibility requirements: dial feet must match the NH35, hand tube sizes must match the NH35 pinion posts, and the crystal must fit the case. Use the Assemble Watches builder to verify all dimensions before ordering.
- Are SKX007 and SRPD parts interchangeable?
- Mostly yes. Most aftermarket dials, hands, and bezels sold as SKX-compatible also fit the SRPD (5KX series). The case dimensions and movement footprint are very similar. However, some case geometry differs slightly, so always confirm with the vendor that parts are listed as compatible with both platforms.
- What is the NH35 movement?
- The NH35 is a Seiko SII automatic movement and the most popular choice for Seiko mods. It hacks (stops when the crown is pulled), hand-winds, and runs at 21,600 bph. Same footprint as the older 7s26 it replaces, making it a drop-in upgrade for SKX007 and SRPD platforms.
- What is the difference between NH35 and NH36?
- Both are identical in case footprint and features (hacking, hand-winding, 21,600 bph). The NH36 adds a day display alongside the date. Choose based on whether your dial has a date window at 3 o'clock or a day/date window.
- What dial feet compatibility do I need to check?
- Dial feet are the small metal tabs on the underside of a dial that slot into holes in the movement. For NH35 mods, you need dials with NH35-compatible dial feet positions. Most aftermarket dials listed as 'NH35 compatible' or 'SKX007 compatible' will be correctly specced, but always verify dimensions before ordering.
Tools
- What tools do I need to mod a Seiko watch?
- The essential kit: spring bar tool (strap changes), case back wrench (screw-down backs), hand setting and removal kit (dial and hand work), Rodico putty (dust and fingerprint removal), and a watchmaker's loupe. A crystal press is additionally needed for crystal swaps. Don't cheap out: a bad spring bar tool scratches cases.
- What is Rodico and do I need it?
- Rodico is a brand of waxy cleaning putty used to lift dust and fingerprints from dials and hands without scratching. Essential for any dial or hand work. One fingerprint on a dial shows up clearly under a crystal. It costs very little and lasts a long time.
- Do I need a crystal press for a Seiko mod?
- Only if you're doing a crystal swap. You cannot safely seat a new crystal without one; improvising damages the crystal or the case. If you're only doing strap, bezel, or dial work, you don't need a crystal press.
Using Assemble Watches
- What is Assemble Watches?
- Assemble Watches is a free online watch mod visualizer and planner for Seiko platforms. You select a case, dial, hands, bezel, and bracelet, and the tool checks part compatibility automatically and generates a complete parts list with vendor links, all before you spend anything.
- Is Assemble Watches free?
- Yes, completely free. No account required, no paid tiers. It's a community tool built to make the planning side of watch modding faster and less frustrating.
- Where can I plan a custom watch build online?
- Assemble Watches (assemble.watch/build) is built specifically for this. Mix and match Seiko mod parts, get automatic compatibility checking, and generate a parts list. Free, no sign-up needed.