3D models of the engineering class usually have a large number of connected components, with small numbers of large triangles, often with arbitrary connectivity. A saddle protractor having a plurality of alignment tabs is engaged with a standard framing square by placing the saddle protractor in fact to face contact with the framing square and in alignment with the alignment tabs. A divider is provided that splits the burner chambers into two separate sections in such a manner that one section includes burner chambers greater in number than the other section. During the rotation of the semiconductor substrate, the flow head portion applies a fluid to the edge surface while the collection head portion collects fluid from the edge surface.