Definition
The rehaut (or chapter ring) is the interface between the dial and the crystal, forming the inner wall of the case opening.
It defines:
- The visual transition from dial to case
- The alignment reference for indices and markers
It is a critical interface within movement-led case design, linking internal geometry to visible alignment.
Why Rehaut Design Matters
The rehaut directly affects:
- Visual alignment
- Perceived quality
- Legibility
Incorrect design results in:
- Misaligned indices
- Uneven spacing
- Visual distortion
Even small errors are immediately visible.
Functional Role
The rehaut serves both:
- A structural role (part of case geometry or separate component)
- A visual role (index reference and framing element)
It must integrate with:
- Dial position
- Crystal position
- Case internal geometry
Rehaut Types
Integrated Rehaut
Machined directly into the case.
Advantages:
- High rigidity
- Fewer components
Risks:
- Dependent on machining accuracy
- Difficult to adjust after production
Separate Chapter Ring
A separate component installed between dial and crystal.
Advantages:
- Adjustable alignment
- Greater design flexibility
Risks:
- Additional tolerance layer
- Potential for assembly misalignment
Alignment Requirements
The rehaut must align with:
- Dial indices
- Crown position (12–3–6–9 orientation)
- Case geometry
Alignment must be:
- Rotationally correct
- Radially centred
- Axially positioned
Rotational Alignment
Critical for index alignment and visual accuracy.
Achieved through:
- Keyed features
- Controlled assembly positioning
Even minimal rotational error is visually detectable.
Radial Alignment
The rehaut must be concentric with:
- Dial
- Case opening
Misalignment results in:
- Uneven spacing
- Visual imbalance
Radial control is governed by Radial Clearance (Movement to Case Fit).
Axial Positioning
The vertical position of the rehaut affects:
- Visual depth
- Crystal clearance
- Dial visibility
Incorrect positioning results in:
- Visual distortion
- Reduced legibility
Axial position must be coordinated with Axial Clearance (Vertical Spacing).
Tolerance Considerations
Rehaut alignment depends on:
- Case machining tolerance
- Dial positioning tolerance
- Assembly variation
Tolerance stack affects:
- Concentricity
- Alignment accuracy
This behaviour is defined in Watch Case Tolerances (Engineering Guide).
Interaction with Crystal
The rehaut defines the interface with the crystal.
It affects:
- Visible crystal edge
- Internal reflections
- Perceived depth
Crystal position must align with rehaut geometry.
Interaction with Dial
The rehaut frames the dial and defines visual reference.
It must:
- Maintain consistent spacing
- Align with dial indices
Dial and rehaut must be designed together.
Manufacturing Considerations
Integrated rehaut:
- Requires precise machining
- Sensitive to tool accuracy
Separate rehaut:
- Requires controlled assembly
- Must maintain consistent positioning
Failure Modes
Common issues include:
- Rotational misalignment → index offset
- Radial misalignment → uneven spacing
- Incorrect axial position → distorted appearance
- Assembly variation → inconsistent builds
All failures are immediately visible.
Implementation
Effective rehaut design requires:
- Defining alignment reference points
- Controlling tolerance across case and dial
- Using keyed or indexed features
- Validating alignment during assembly
System Context
This page defines the visual and geometric interface between internal components and the case opening.
It connects directly to:
- Dial Seat Geometry
- Internal Case Geometry & Movement Cavity Sizing
- Watch Case Tolerances (Engineering Guide)
Final Statement
The rehaut defines the visual alignment interface between the dial and case.
It must maintain rotational accuracy, radial concentricity, and axial position within defined tolerance limits to ensure both functional integration and perceived quality.