From Negative Knowledge to Best Practices for Enhancing Reusability of Sketches in Procedural 3D CAD Models

Procedural CAD models are the primary source of detailed mechanical designs as they are editable, can convey design intent and be enriched with design and manufacturing information. However, many companies still spend significant time modifying low-quality procedural CAD models, which are often poorly structured or become unusable when geometric changes are made. Current best practices focus mainly on "how to do it well," which can frustrate users who struggle to identify the sources of errors and determine how to resolve them, leading to issues that often persist when integrating models into other applications. In contrast, we propose practices based on the principle of “how to avoid doing it wrong” derived from analyzing negative knowledge in CAD modeling. This paper contributes to advancing the quality of 3D procedural models. Our framework adopts the three levels of quality identified in the literature: usability, re-usability, and design intent richness, while focusing specifically on deriving best prac-tices to prevent failures, based on negative knowledge related to reusability. We build on the premise that quality issues hindering reusability can be categorized into three interrelated but largely independent types, each affecting the sketches, datums, or features within a procedural model’s tree structure. In this work, we address the study of sketches. The negative impact of typical failures, identified through representative case studies that illustrate both design and redesign errors, is analyzed to extract best practices that ensure CAD model reusability. While this study results in a practical guide for avoiding sketch-related errors that compromise the reusability of CAD models, the main contribution lies in demonstrating a framework that transforms negative knowledge into effective best practices.