The Sellita SW200-1 is widely used.
Most case designs built around it fail for the same reasons:
- incorrect movement fit
- uncontrolled tolerance stack
- misaligned crown tube
- inconsistent sealing
This system exists to remove those failure points.
What This Is
A movement-led case core built around the SW200-1.
It defines:
- internal case geometry
- movement seating and retention
- stem axis location
- axial stack baseline
- critical interfaces for sealing
It is not styling.
It is the internal structure that allows a case to:
- assemble
- align
- seal
What It Includes
- Parametric 3D CAD geometry
- Movement envelope integrated into case core
- Defined clearances for movement fit
- Stem axis and crown tube reference
- Axial stack framework
- Section views of all critical interfaces
All geometry is built in mm and constrained for manufacturability.
What Problems It Solves
Movement Fit
- Defines radial clearance
- Prevents movement instability
- Ensures consistent seating
Crown and Stem Alignment
- Fixes stem axis in 3D space
- Defines crown tube position
- Removes alignment guesswork
Axial Stack
- Establishes baseline stack
- Prevents hand/crystal interference
- Controls caseback closure
Tolerance Framework
- Built with clearance and compression in mind
- Designed for real machining variation
- Avoids nominal-only failure
Sealing Interfaces
- Defines caseback compression geometry
- Supports crystal interface design
- Integrates with gasket-based systems
What This Is Not
- Not a finished case design
- Not external styling
- Not a render model
This is the internal system that external design must conform to.
When To Use It
- Designing a case around the SW200-1
- Preparing for CNC prototyping
- Replacing a failed or inconsistent design
- Building a repeatable case architecture
Relation to the System
This is built directly from:
- Watch Movement Dimensions and Case Fit
- Watch Case Tolerances Explained
- Watch Crown and Stem Alignment
- Watch Caseback Design
- Watch Crystal Fit and Gasket Compression
It implements those constraints in geometry.
Output
Using this system, you can:
- build external case geometry around a defined core
- maintain alignment and fit
- avoid tolerance-related failures
- move directly to manufacturable CAD