SW200-1 Dimensions & Technical Data
Definition
This page defines the critical dimensions and engineering parameters of the Sellita SW200-1 required for watch case design.
All values are presented for use in movement-led case development.
Why These Dimensions Matter
The SW200-1 defines:
- Internal case geometry
- Crown and stem alignment
- Axial stack height
- Movement retention requirements
Incorrect dimensional assumptions result in:
- Misalignment
- Assembly failure
- Functional issues
All case geometry must be derived from accurate movement data.
Core Dimensions
Movement Diameter
- ~25.6 mm
Defines:
- Minimum internal case diameter
- Movement holder sizing
- Radial clearance requirements
Movement Height
- ~4.6 mm
Defines:
- Axial stack baseline
- Case thickness minimum
- Caseback positioning
Stem Height (Critical)
- ~1.80 mm (from movement base)
Defines:
- Crown tube vertical position
- Case wall geometry
- Stem alignment
This is a primary constraint.
Stem Position
- Fixed relative to movement centre
Defines:
- Crown placement
- Case symmetry
- External design constraints
Dial Interface
Dial Diameter
- Typically ~28.0–29.0 mm (varies by design)
Defines:
- Dial seat geometry
- Rehaut alignment
- Visual proportions
Dial Feet Position
- Movement-specific
Defines:
- Dial attachment
- Alignment relative to movement
Must be matched exactly.
Hand Stack Parameters
Hand Height Requirements
Includes:
- Hour hand clearance above dial
- Minute hand clearance above hour hand
- Seconds hand clearance below crystal
Defines:
- Axial spacing
- Crystal clearance
- Dial positioning
Hand stack must be validated within full tolerance range.
Crown and Stem Interface
Stem Diameter
- Standard SW200 specification
Defines:
- Crown tube internal diameter
- Seal interface
Stem Engagement
Defines:
- Crown connection depth
- Functional reliability
Must allow:
- Full engagement
- No axial preload
Movement Mounting
Outer Geometry
Defines:
- Clamp positions
- Movement holder design
Fixing Points
- Movement-specific screw positions
Defines:
- Retention system design
- Case internal features
Tolerance Considerations
Movement dimensions include variation.
Design must account for:
- Manufacturing tolerance
- Assembly variation
Critical areas:
- Stem height
- Movement thickness
- Outer diameter
Nominal values are insufficient.
Clearance Requirements
Typical design clearances:
- Radial: ~0.02–0.05 mm
- Axial: ~0.02–0.05 mm (controlled)
Clearance must:
- Allow assembly
- Prevent movement under load
Interaction with Case Design
These dimensions define:
- Internal case geometry
- Dial seat position
- Crown tube location
- Caseback position
All case systems depend on these values.
System Context
This page connects directly to:
- Movement Securing Methods
- Axial Retention & Stack Control
- Crown / Stem Alignment
- Tolerance Stack Design
Final Statement
The SW200-1 defines the fundamental constraints of the watch case.
Accurate use of its dimensions is required to produce a functional, manufacturable, and reliable case design.