131 Copyright Goodheart-Willcox Co., Inc. Learning Objectives After completing this chapter, you will be able to: ✓ Create solids and surfaces by extruding profi les. ✓ Extrude regions. ✓ Extrude surfaces. ✓ Create symmetrical 3D solids and surfaces by revolving profi les. ✓ Revolve regions. ✓ Revolve surfaces. ✓ Extrude and revolve objects using mathematical expressions and constraints. ✓ Use solid extrusions and revolutions as construction tools. A complex shape can be created by extruding a profi le into a 3D solid or surface model. You have been introduced to the operation in previous chapters. Symmetrical objects can be created by revolving a profi le about an axis to create a new shape. This chapter discusses the EXTRUDE and REVOLVE commands and using these commands as construction tools. Creating Extruded Models Creating Extruded Models An extrusion is a profi le that has been “extruded” into a 3D solid or surface. The EXTRUDE command allows you to create extrusions from lines, arcs, elliptical arcs, 2D and 3D polylines, 2D and 3D splines, circles, ellipses, 2D solids, 3D solid faces and edges, regions, planar surfaces, surface edges, and donuts . By default, closed objects, such as circles, polygons, closed polylines, and donuts, are converted to a solid extrusion when they are extruded. A solid extrusion repre- sents a solid object and has mass properties. Open-ended objects, such as lines, arcs, polylines, elliptical arcs, and splines, are converted to a surface extrusion when they are extruded. Surface extrusions have no mass properties. Extrusions can be created along a straight line or along a path curve. A taper angle can also be applied as you extrude an object. Figure 6-1 illustrates a polygon extruded into a solid. When the EXTRUDE command is selected, you are prompted to select the objects to extrude. Select the objects and press [Enter]. You are then prompted for the extrusion EXTRUDE Ribbon Home Modeling Solid Solid Extrude Surface Create Extrude Type EXTRUDE EXT Model Extrusions and Revolutions CHAPTER 6 6