Document Information

Document Title	Understanding Ghost Parts
Document Number	0006
Version Number	1.0
Effective Date	23 May 25
Prepared By	Engines
Reviewed By
Approved By
Next Review Date	23 Jun 25
Location	GitHub - hover-stop/docs

Version	Date	Description of Change	Changed By
1.0	23 May 25	Initial release	Engines

Understanding Ghost Parts

Ghost parts are virtual or placeholder components used in the design and assembly process to represent physical constraints, volumes, or conceptual elements that do not correspond to actual manufactured parts. They are commonly used in CAD models and assembly documentation to ensure proper fit, alignment, and functionality of the overall design.

Purpose of Ghost Parts

1. Define Spatial Constraints
   Ghost parts are used to represent the physical boundaries or volumes that other components must fit within or avoid. For example:
   • 14619 - Ghost Volume, Throttle Body, Inner defines the inner limits of the throttle body design.
   • 77875 - Ghost Volume, Throttle Body, Outer represents the outer boundaries of the throttle body.

2. Facilitate Design Alignment
   By including ghost parts in CAD models, designers can ensure that all components align correctly and do not interfere with each other.

3. Document Conceptual Elements
   Ghost parts can represent conceptual elements, such as airflow paths, wiring clearances, or mounting zones, that are critical to the design but not physically manufactured.

Characteristics of Ghost Parts

• Non-Physical: Ghost parts are not manufactured or assembled; they exist only in documentation and CAD models.
• Cost-Free: Since they are not real parts, their cost is typically listed as $0.00.
• Metadata: Ghost parts are documented in the BOM and metadata files for reference but are marked with a Ghost part type.
• Parent Assembly: Ghost parts are often grouped under a “collector” assembly, such as 98415 - Ghost Parts, to keep them organized.

Examples in the HSI Mk.1 Project

• Inner Ghost Volume (14619): Represents the internal space constraints for the throttle body design.
• Outer Ghost Volume (77875): Defines the maximum external dimensions of the throttle body.

Ghost Parts Used In Drawings

Best Practices for Using Ghost Parts

1. Clearly Document Purpose
   Include a detailed description in the metadata and requirements documents to explain the role of each ghost part.

2. Use in CAD Models
   Incorporate ghost parts into CAD assemblies to visualize spatial constraints and ensure proper alignment.

3. Exclude from Manufacturing
   Ensure ghost parts are excluded from manufacturing and procurement processes by marking them as Ghost in the BOM.

By using ghost parts effectively, designers can streamline the development process and ensure that all components fit and function as intended within the defined design constraints.