Copyright Goodheart-Willcox Co., Inc. 142 AutoCAD and Its Applications—Advanced There are two ways to create a hole. You can draw a circle and extrude it to create a cylinder or you can draw a solid cylinder. Either way, you need to subtract the cylinder to create the hole. Drawing a solid cylinder is probably easiest. When prompted for a center, use the Node object snap to select the point. Then, enter the diameter. Finally, enter a negative height so that the cylinder extends into the solid or drag the cylinder down in the 3D view so it extends all of the way through the block. The actual height is not critical, as long as it extends through the block. You can either copy the fi rst cylinder to the second point or draw another cylinder. When both cylinders are located, use the SUBTRACT command to remove them from the solid. The object is now complete and should look like Figure 6-16. Creating Features with Revolve The REVOLVE command is very useful for creating symmetrical, round objects. Many times, however, the object you are creating is not completely symmetrical. For Figure 6-16. Most of this object can be created by extruding a profile. However, the holes must be added after the extruded solid is created. Figure 6-17. This is the profile that will be extruded for the clamping block. Notice the dimensional constraints that have been applied. Figure 6-18. Draw a construction line (shown here in color) and divide it into three parts.