Circular hole recognition for STL-based toolpath generation

Purpose - This paper presents a unique method to recognize circular holes from 3D models in the STL format. The topological information generated by this method enables identification of holes and tool path generation for holes which should be drilled rather than milled.Design methodology approach - A method based on a set of developed algorithms is used to identify closed loops from a STL model, identify which closed loops correspond to cylindrical holes, find hole orientations, locations and diameters, and calculate the depth for the recognized holes. The developed procedure and algorithms have been implemented in Visual C++ to illustrate the efficacy of the method.Findings - The implementation results showed that the developed algorithms can successfully recognize circular holes of differing sizes on both simple and complex surfaces, and in any orientation. Tool paths can thus be generated from STL models to more efficiently and accurately machine circular holes.Research limitations implications - The developed method requires that at least one simple closed loop exist for each potential hole.Originality value - A new and unique hole recognition method for use with STL models was developed. This method is useful for accurately and efficiently machining parts with circular holes from STL models as well as finish machining near-net shape parts with circular holes created using rapid prototyping.