Copyright Goodheart-Willcox Co., Inc. 314 AutoCAD and Its Applications—Advanced The 2points option is the default. Pick two points to defi ne the “hinge” about which the face will rotate. Then, provide the rotation angle and exit the command. The Axis by object option allows you to use an existing object to defi ne the axis of rotation. You can select the following objects. • Line. The selected line becomes the axis of rotation. • Circle, arc, or ellipse. The Z axis of the object becomes the axis of rotation. This Z axis is a line that passes through the center of the circle, arc, or ellipse and is perpendicular to the plane on which the 2D object lies. • Polyline or spline. A line connecting the polyline or spline’s start point and endpoint becomes the axis of rotation. After selecting an object, enter the angle of rotation and exit the command. When you select the View option, the axis of rotation is perpendicular to the current view, with the positive direction coming out of the screen. This axis is identical to the Z axis when the UCS command View option is used. Specify the point through which the axis passes. Next, enter the angle of rotation and exit the command. The Xaxis, Yaxis, and Zaxis options prompt you to specify a point. The X, Y, or Z axis passing through that point is used as the axis of rotation. Then, enter the angle of rotation and exit the command. Figure 12-7 provides several examples of rotated faces. Notice how the fi rst and second pick points determine the direction of positive and negative rotation angles. NOTE NOTE A positive rotation angle moves the face in a clockwise direction looking from the fi rst pick point to the second. Conversely, a negative angle rotates the face counterclock- wise. If the rotated face will intersect or otherwise interfere with other faces, an error message indicates that the operation failed or no solution was calculated. In this case, you may wish to try a negative angle if you previously entered a positive one. In addi- tion, you can try using the opposite edge of the face as the axis of rotation by picking the appropriate points. Pick 1 Pick 2 Pick 2 Pick 1 Original Object +30° Angle –30° Angle +30° Angle –30° Angle Original Object Figure 12-7. When rotating faces, the first and second pick points determine the direction of positive and negative rotation angles.