Topological naming problem - FreeCAD Documentation
Hacker News
February 21, 2026
AI-Generated Deep Dive Summary
The topological naming problem in FreeCAD occurs when a shape's internal name changes after a modeling operation, such as a pad, cut, or union. This issue can cause dependent features to malfunction, leading to incorrect computations or broken models. While this problem is common in CAD software, it is particularly challenging for FreeCAD users, especially those working with solids in the PartDesign Workbench or dimensioning models in TechDraw. The issue arises due to how FreeCAD's OCCT kernel handles shape updates, and while most other CAD programs use heuristics to minimize such problems, FreeCAD has been actively addressing this through its new naming algorithm since version 1.0.
The problem often affects users during the modeling process. For example, modifying a sketch or pad can alter the names of associated faces, leading to misaligned references in dependent features. This can result in invalid geometry, like sketches appearing in incorrect positions or pads being disconnected from their intended solids. However, FreeCAD provides tools to mitigate this issue. Users are advised to remap sketches and pads manually when errors occur, ensuring that references remain accurate. Additionally, employing datum objects like planes or local coordinate systems can help create more stable models less prone to topological errors.
Despite these challenges, ongoing efforts in FreeCAD aim to automate and streamline the resolution of topological naming issues. The new naming algorithm introduced in version 1.0 seeks to reduce manual intervention by automatically fixing problems or guiding users toward solutions. As development progresses, future versions are expected to expand this functionality, offering even more robust repair mechanisms. For tech enthusiasts and professionals using FreeCAD for engineering projects, addressing the topological naming problem is critical for maintaining workflow efficiency and model integrity. By understanding best practices and leveraging FreeCAD's evolving tools, users can minimize disruptions caused by this issue and achieve more reliable modeling outcomes.
Verticals
techstartups
Originally published on Hacker News on 2/21/2026