How do I check Seiko mod part compatibility?

The most important checks are: (1) dial feet pattern matches your movement — NH35 or NH36, (2) hand tube sizes match the movement pinion posts, (3) crystal diameter matches your case exactly, (4) bezel ring fits your case diameter. Assemble Watches automates all of these checks as you select parts in the builder.

Are SKX007 and SRPD parts compatible with each other?

Mostly yes. Most aftermarket dials, hands, bezel inserts, and bracelets sold as SKX007-compatible also fit SRPD (5KX series) platforms. However, some third-party cases differ slightly in bezel diameter or crystal fit. Always check the vendor listing for explicit compatibility confirmation.

What happens if I use incompatible Seiko mod parts?

The consequences range from minor (a dial that wobbles slightly) to serious (a crystal that pops out under water pressure, or hands that can't be pressed onto the movement pinion posts). Checking compatibility before ordering saves time, money, and the frustration of a build that can't be assembled.

Do NH35 and NH36 use the same parts?

Yes, for most modding purposes. The NH35 and NH36 share the same case footprint, dial feet positions, and hand tube sizes. The only difference is the NH36 adds a day wheel alongside the date. Dials must have the correct window cutout for whichever movement you use.

Assemble Watches

Seiko Mod Compatibility Checklist

Before ordering Seiko mod parts, run through this checklist. The Assemble Watches builder automates all of these checks — but understanding what to look for helps you catch issues the tool might not know about yet.

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Compatibility checks before you order

Dial feet pattern matches the movement

High

NH35 and NH36 share the same dial feet positions. Dials labeled 'NH35 compatible' or 'SKX007 compatible' will usually work. Confirm before ordering — incorrect feet positions mean the dial won't seat.

Hand tube sizes match the movement pinion posts

High

The hour, minute, and seconds hands each have different tube inner diameters. NH35/NH36 pinion post diameters are well-documented — most aftermarket hands listed as NH35-compatible will be correct, but verify with the vendor.

Crystal outer diameter matches the case

High

Crystals are measured in tenths of a millimetre. A mismatch of even 0.1mm can prevent proper seating or cause the crystal to fall out. Always confirm the exact diameter specified by the case manufacturer.

Bezel ring fits the case diameter

Medium

Most aftermarket bezels are listed as SKX007 or SRPD-compatible. The outer diameters differ slightly between manufacturers — confirm the bezel is explicitly listed for your case.

Bezel insert fits the bezel ring

Medium

Bezel insert inner diameter must match the bezel ring. This is usually consistent within a platform (SKX007, SRPD) but can vary between aftermarket bezel manufacturers.

Lug width matches the bracelet or strap

Low

Most SKX007 and SRPD-platform cases use 20mm lug width. Confirm before ordering bracelets or straps — especially with third-party cases where lug width may vary.

Case accepts the NH35 movement footprint

Medium

The NH35 has the same footprint as the 7s26 it replaced, so any SKX007-spec case will accept it. Third-party cases from reputable suppliers specify NH35 compatibility — confirm this rather than assuming.

Crown and stem thread pattern matches the case

Low

Less commonly an issue when buying complete cases, but relevant if sourcing a crown separately. The crown must thread onto the stem correctly and seal properly in the case tube.

Let the builder check for you

Assemble Watches checks dial feet compatibility, hand tube sizes, crystal diameter, and movement fit automatically as you select parts. If something won't work, you'll see a warning before you order.

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Common questions

How do I check Seiko mod part compatibility?: The most important checks are: (1) dial feet pattern matches your movement — NH35 or NH36, (2) hand tube sizes match the movement pinion posts, (3) crystal diameter matches your case exactly, (4) bezel ring fits your case diameter. Assemble Watches automates all of these checks as you select parts in the builder.
Are SKX007 and SRPD parts compatible with each other?: Mostly yes. Most aftermarket dials, hands, bezel inserts, and bracelets sold as SKX007-compatible also fit SRPD (5KX series) platforms. However, some third-party cases differ slightly in bezel diameter or crystal fit. Always check the vendor listing for explicit compatibility confirmation.
What happens if I use incompatible Seiko mod parts?: The consequences range from minor (a dial that wobbles slightly) to serious (a crystal that pops out under water pressure, or hands that can't be pressed onto the movement pinion posts). Checking compatibility before ordering saves time, money, and the frustration of a build that can't be assembled.
Do NH35 and NH36 use the same parts?: Yes, for most modding purposes. The NH35 and NH36 share the same case footprint, dial feet positions, and hand tube sizes. The only difference is the NH36 adds a day wheel alongside the date. Dials must have the correct window cutout for whichever movement you use.

BuildOpen the Builder →Automatic compatibility checking as you select parts.PlanParts Planner →Build a complete Seiko mod parts list.ReadNH35 Movement Guide →NH35 specs, compatibility, and what to know before modding.ReferenceNH35 Compatible Dials →Dial size, feet, date aperture, and case clearance checks.FAQWatch Modding FAQ →Common questions about parts, tools, and builds.

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