Project Leaders: Ravi Ganti, MS (1997), John Pickens, MS Candidate
Tel: (864) 656-7178
mail-to: jpicken@ces.clemson.edu

All commercially available Rapid Prototyping (RP) machines are based on a process that converts CAD drawings to machine instructions. Currently, the only control mechanism used to either drive a laser beam or a nozzle is vector based. The advantages of such a controller are obvious: (1) Two points define the start and the end of the vector; (2) CAD software inherently generates vectors to drive plotters, and it is relatively easy to convert arbitrary surfaces to triangles which are sliced to form a series of vectors.

Since accuracy is becoming a major concern for users of RP hardware who aim at producing finished parts, or molds to produce finished parts, the vector based approach is a limiting factor since curved features are replaced by vectors. Furthermore, most CAD vendors are migrating to parametric based representation of surfaces, and the ability to draw exact curves would significantly improve surface quality. Clemson University has developed an algorithm to slice parametric surfaces and generate parametric curves. Presently, vectors approximate these parametric curves, and the improvement in accuracy is already visible over triangle based tessellations. The next step is to directly draw parametric curves to close the page on the accuracy question in a plane.