This paper describes an expert system for a class of automated cutting operations which are of practical use in the offshore manufacturing industry. These operations include plasma cutting, oxy-fuel cutting, laser cutting and water-jet cutting. The common features in these processes, which define this class of cutting operations, are: 1) the work material is cut by the sweeping action of a line segment; 2) the cutting effect terminates at an imprecise point along the cutting segment; 3) the cutting task at hand can be fully described by the surface-boundary representation of the workpiece and the surface to be cut. The fundamental problem in such a planning task is that neither a strictly geometrical analysis, nor a purely heuristic approach is sufficient when considered alone. In this paper, we present a knowledge-based system which blends heuristics with spatial reasoning within the framework of a solid modeling system.