AutoCAD and Its Applications—Comprehensive 2020, 27th Edition Page 96 (1168 of 1650)

Copyright Goodheart-Willcox Co., Inc. 96 AutoCAD and Its Applications—Advanced Using a Dynamic UCS Using a Dynamic UCS A powerful tool for 3D modeling is the dynamic UCS function. A dynamic UCS is a UCS temporarily located on any existing face of a 3D model. The function is activated by picking the Dynamic UCS button on the status bar, pressing the [Ctrl]+[D] key combi- nation, pressing [F6], or setting the UCSDETECT system variable to 1. The Dynamic UCS button does not appear on the status bar by default. Select the Dynamic UCS option in the status bar Customization fl yout to add the Dynamic UCS button to the status bar. When the pointer is moved over a model surface when using a drawing or modeling command, the XY plane of the UCS is aligned with that surface. This is especially useful when adding primitives or shapes to model surfaces. In addition, dynamic UCSs are useful when inserting blocks and xrefs, locating text, editing 3D geometry, editing with grips, and making area calculations. A limitation of using a dynamic UCS is that it operates as a temporary override to the current UCS. Once the operation is complete, the UCS reverts to its previous loca- tion. A more fl exible option is to use the full range of capabilities inherent in the UCS icon as previously discussed. UCSDETECT Type UCSDETECT [Ctrl]+[D] [F6] Toolbar Status Bar Dynamic UCS Pick B A D C Specify the radius or diameter Specify the height Figure 4-22. Moving the UCS allows you to draw a cylinder on the angled face of the object. The X-ray visual style is displayed for visualization purposes. A—To set the center point of the base, use the Center of face 3D object snap and select the center of the face. B—Set the radius or diameter of the base. C—Set the height of the cylinder. D—The completed cylinder.

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Copyright Goodheart-Willcox Co., Inc. 96 AutoCAD and Its Applications—Advanced Using a Dynamic UCS Using a Dynamic UCS A powerful tool for 3D modeling is the dynamic UCS function. A dynamic UCS is a UCS temporarily located on any existing face of a 3D model. The function is activated by picking the Dynamic UCS button on the status bar, pressing the [Ctrl]+[D] key combi- nation, pressing [F6], or setting the UCSDETECT system variable to 1. The Dynamic UCS button does not appear on the status bar by default. Select the Dynamic UCS option in the status bar Customization fl yout to add the Dynamic UCS button to the status bar. When the pointer is moved over a model surface when using a drawing or modeling command, the XY plane of the UCS is aligned with that surface. This is especially useful when adding primitives or shapes to model surfaces. In addition, dynamic UCSs are useful when inserting blocks and xrefs, locating text, editing 3D geometry, editing with grips, and making area calculations. A limitation of using a dynamic UCS is that it operates as a temporary override to the current UCS. Once the operation is complete, the UCS reverts to its previous loca- tion. A more fl exible option is to use the full range of capabilities inherent in the UCS icon as previously discussed. UCSDETECT Type UCSDETECT [Ctrl]+[D] [F6] Toolbar Status Bar Dynamic UCS Pick B A D C Specify the radius or diameter Specify the height Figure 4-22. Moving the UCS allows you to draw a cylinder on the angled face of the object. The X-ray visual style is displayed for visualization purposes. A—To set the center point of the base, use the Center of face 3D object snap and select the center of the face. B—Set the radius or diameter of the base. C—Set the height of the cylinder. D—The completed cylinder.

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Copyright Goodheart-Willcox Co., Inc. Chapter 4 Understanding Three-Dimensional Coordinates and User Coordinate Systems 95 UCS icon onto the angled face of the object. Notice how the icon immediately rotates to match the orientation of the highlighted face it is resting on. Test this by moving the icon to each visible face. As you move the pointer over the object faces, note that hidden faces are not highlighted. Therefore, you cannot work on those faces. If you wish to work on a hidden face, you must fi rst change the viewpoint to make that face visible. You can use the view cube or press and hold the [Shift] key while pressing the mouse wheel button to change the viewpoint dynamically without interrupting the current command. Now return the UCS icon to the angled face, being careful to ensure that the icon is oriented in the manner shown in Figure 4-21B. The X-ray visual style is shown in Figure 4-21B to help show the proper UCS orientation. You may have to fi rst move the icon to the top face to achieve the proper UCS orientation, and then move to the angled face. Use the Endpoint object snap to select the lower-left corner of the angled face as the new origin. Next, select the CYLINDER command. You are prompted to select a center point of the base. To locate a 1.5″ diameter cylinder in the center of the angled face, use the following procedure. 1. When prompted to specify the center point of the base, press [Shift] and right-click in the drawing area and pick 3D Osnap from the shortcut menu. Then, pick Center of face from the cascading menu. See Figure 4-22A. 2. Move the pointer over the angled face. Notice the crosshairs are aligned with the angled face. A circular 3D snap pick point appears at the center of the face. Select this point. 3. Specify the 1.5 unit diameter for the base. See Figure 4-22B. 4. Specify a cylinder height of .35 units. See Figure 4-22C. 5. The cylinder is properly located on the angled face. See Figure 4-22D. If you do not wish to retain the location of the current UCS after drawing a feature, change it as needed using the UCS icon. If necessary, you can also quickly restore the previous UCS. To do so, simply right-click on the UCS icon and pick Previous from the UCS icon shortcut menu. Refer to Figure 4-19. Do this after drawing the cylinder so that the UCS is oriented parallel to the side of the object. PROFESSIONAL TIP PROFESSIONAL TIP Selecting 3D object snaps can be automated for solid model construction. Simply right- click on the 3D Object Snap button on the status bar and select the snap mode you wish to use. The 3D Object Snap button does not appear on the status bar by default. Select the 3D Object Snap option in the status bar Customization fl yout to add the 3D Object Snap button to the status bar. To set multiple snap modes, pick the Object Snap Settings… option, and then select the appropriate modes in the Drafting Settings dialog box. Be sure to turn on the 3D Object Snap button before using a modeling command. Exercise 4-4 www.g-wlearning.com/CAD/ Complete the exercise on the companion website.

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Copyright Goodheart-Willcox Co., Inc. Chapter 4 Understanding Three-Dimensional Coordinates and User Coordinate Systems 97 To see how to work with a dynamic UCS, recreate the cylinder on the angled face of the model completed in the previous discussion. First, delete the existing cylinder by picking on the cylinder and pressing the [Delete] key. Make sure that the UCS is oriented parallel to the side of the object. Refer to Figure 4-18. Next, select the CYLINDER command. Make sure the dynamic UCS function is on. Then, move the pointer over one of the surfaces of the object. Notice that the 3D crosshairs change when they are moved over a new surface. The red (X) and green (Y) crosshairs are fl at on the face. For ease of visualizing the 3D crosshairs as they are moved across different surfaces, you can display the XYZ labels on the crosshairs. Open the Options dialog box, select the 3D Modeling tab, and activate the Show labels for dynamic UCS option in the 3D Crosshairs area. The CYLINDER command is currently prompting to select a center point of the base. If you pick a point, this sets the center of the cylinder base and temporarily relocates the UCS so its XY plane lies on the selected face. When the command is completed, the UCS reverts to its previous orientation. Using the CYLINDER command options and the steps presented earlier, draw a 1.5″ diameter cylinder in the center of the angled face. When using the dynamic UCS function, experiment with the behavior of the crosshairs as they are moved over different surfaces. The orientation of the crosshairs is related to the edge of the face that they are moved over. Can you determine the pattern by which the crosshairs are turned? The X axis of the crosshairs is always aligned with the edge that is crossed. If you want to temporarily turn off the dynamic UCS function while working in a command, press and hold the [Shift]+[Z] key combination while moving the pointer over a face. As soon as you release the keys, the dynamic UCS function is reinstated. Additional Ways to Change the UCS Additional Ways to Change the UCS As you have seen, the UCS can be moved to any location and rotated to any angle desired using the UCS icon grips. Location and alignment are controlled using the origin grip, and exact rotation of the three different UCS axes is controlled using the axis grips. The same UCS options are available when using the UCS command, but the UCS icon provides a quick alternative to entering the command or making ribbon or menu selections. The following sections discuss the UCS options available when using the UCS icon grips or the UCS command. Moving and Aligning the UCS The UCS icon origin grip is used to quickly move and align the UCS. Once the UCS icon is selected to display grips, you can pick on the origin grip and drag the icon dynamically. For example, drag the UCS icon to a model surface and orient the UCS parallel to that surface. If you are using dynamic input, you can enter a distance and angle defi ning a new location. You can also move the pointer over the grip to display the grip menu, as previously discussed. Pick Move Origin Only to relocate the UCS in its current orientation to a different origin point. Pick Move and Align to relocate the UCS to a new location and align it with an object face. Use object snaps for accuracy. When the UCS icon is moved along a curved surface or solid, it will always remain normal to that object. In other words, the Z axis of the UCS will project from the center point of the radius curve. See Figure 4-23. In the example shown, the UCS is moved to a point on the outer surface of the model using the Move and Align option. Notice the direction of the Z axis in Figure 4-23C. If dynamic input is on, a tooltip is displayed when using the Move and Align option. You can press the [Ctrl] key to cycle through the options. The options are displayed on the command line to indicate the current mode.

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