Copyright Goodheart-Willcox Co., Inc. Chapter 6 Model Extrusions and Revolutions 143 example, look at the camshaft in Figure 6-19. For the most part, this is a symmetrical, round object. However, the cam lobes are not symmetrical in relation to the shaft and bearings. The REVOLVE command can be used to create the shaft and bearings. Then, the cam lobes can be created and added. Start a new drawing and make sure the WCS is the current UCS. Using the PLINE command, draw the profi le shown in Figure 6-20A. This profi le will be revolved through 360°, so you only need to draw half of the true plan view of the cam profi le. The profi le represents the shaft and three bearings. Next, display the drawing from the southwest isometric preset viewpoint. Then, use the REVOLVE command to create the base camshaft as a 3D solid. Pick the endpoints shown in Figure 6-20A as the axis of revolution. Revolve the profi le through 360°. Perform a zoom extents and set the Conceptual visual style current to clearly see the object. Now, you need to create one cam lobe. Change the UCS to the left orthographic preset. Then, draw a construction point in the center of the left end of the camshaft. Use the Center object snap and an appropriate PDMODE setting. Next, draw the profi le shown in Figure 6-20B. Use the construction point as the center of the large radius. You may want to create a new layer and turn off the display of the base camshaft. Once the cam lobe profi le is created, use the REGION command to create a region. Then, use the EXTRUDE command to extrude the region to a height of –.5 units (into the camshaft). The extrusion should have a 0° taper. If you turned off the display of the base camshaft, turn it back on. A B P1 P2 Figure 6-19. For the most part, this object is symmetrical about its center axis. However, the cam lobes are not symmetrical about the axis. Figure 6-20. A—This profile will be revolved to create the shaft and bearings. Notice the parallel constraints that have been applied. B—This is the profile of one cam lobe, which will be extruded.