LABORATORY 4: TO CONSTRUCT CAD MULTIPLE VIEWS I AND II

Transcription

1 LABORATORY 4: TO CONSTRUCT CAD MULTIPLE VIEWS I AND II OBJECTIVES: After completing this session, you should be able to: 1. Use the User Coordinate System 2. Convert a solid model to a multiview using the SOLVIEW and SOLDRAW commands. METHODS: STEP 1 Drawings need to be converted into Multiview Drawing, which is the standard method of representing objects for manufacturing processes. In order to do this task, you must understand the World Coordinate Systems (WCS) and User Coordinate System (UCS). 1. Open your class template file. 2. If the WCS icon in your class template file is not the 2D version (see image in Figure 4.1), you should change it to the 2D version through the UCSICON command. Figure 4.1: WCS icon in 2D Coordinate Systems are based on the Cartesian System of X, Y, and Z axes. Many of the commands in AutoCAD require that you alter the coordinate system. University Malaysia Perlis Page 64

2 STEP 2 1. Open your Laboratory 3. Save as Laboratory 4 in your own folder. 2. Change to Model space using Model tab. 3. Change the ucs position to World Coordinate Systems (WCS). Type the ucs command. Press Enter for World Coordinate Systems (WCS). 4. Now you will be introduced to Tiled Viewports. With the vports command, create 4 vports. See Figure 4.2. Figure 4.2: vports Tiled Viewports allow you to see multiple views of the SAME model. This mode is called tilemode because the viewports are arranged in a "tile" pattern. Notice that the arrangement of the Tiled Viewports is regular, and they are all the same size. In the illustration above, the views of the model in the Tiled Viewports are the same. In AutoCAD, you can display a different view of the model in each viewport The next step is to change the Vpoint in three of these viewports, so that you have a Top, Front, and Right side view of the model. University Malaysia Perlis Page 65

3 To create a TOP View of the Model: 1. Click the Top left viewport. 2. Activate vpoint and select the ROTATE option. 3. Angle IN XY Plane: Angle FROM XY Plane: 90 To create a FRONT view of the Model: 1. Click the bottom left viewport. 2. Activate vpoint and select the ROTATE option. 3. Angle IN XY Plane: Angle FROM XY Plane: 0 To create a RIGHT SIDE view of the Model: 1. Click the bottom left viewport. 2. Activate vpoint and select the ROTATE option. 3. Angle IN XY Plane: 0 4. Angle FROM XY Plane: 0 Look at Figure 4.3 to check your orientations. Figure 4.3: View orientations University Malaysia Perlis Page 66

4 The views you see in the viewports are NOT four different models, but the SAME MODEL seen from FOUR DIFFERENT ANGLES. To demonstrate this, click on the viewport in the upper Right (the pictorial view). Add a line anywhere on the model. Notice that the line also appears all viewports. Erase this line. A final thing you should notice is that the WORLD Icon appears in two of these viewports, but the BROKEN PENCIL icon appears in the Front and Right Side viewports. The Broken Pencil icon indicates that you are perpendicular to the World Coordinate Plane (looking at its edge) in those viewports, and the WCS icon cannot be displayed. Use the Vports command to change back to a Single viewport. If needed, use the Vpoint command to rotate your view back to 300 degrees IN the XY Plane and 35 degrees FROM the XY plane. STEP 3 To change the model to a multiview, you will use the SOLVIEW and SOLDRAW commands. The combination of these commands will project a 2D drawing of the solid model. The SOLVIEW command creates floating viewports and automates the creation of the correct viewpoint orientations for a TOP, FRONT, and RIGHT SIDE view in the viewports. This command also creates a series of viewport layers for the Hidden and Dimension lines. Before using the Solview and Soldraw commands, use the orthographic option of the UCS command to change to the FRONT UCS. Switch to Layout1. Figure 4.4: UCS icon University Malaysia Perlis Page 67

5 Once you are in Layout1, look for the Paper Space Icon. If you see a broken pencil instead, activate the UCS command and select the View option. This will orient the UCS to the Layout1 view. CREATING A UCS WITH THE VIEW OPTION 1. Command: Type ucs and press Enter. 2. Enter and option [New/Move/ orthographic /Prev/ Restore/Save/Del/ Apply/?/World] <World>: Type in n for the New option and press Enter. 3. Specify origin of new UCS or [Zaxis/ 3point/ OBject/ Face/ View/X/Y/Z <0,0,0>: Type v to select the View option and press Enter. The UCS will change to match the current Viewpoint (Vpoint) configuration of the whole screen or the active viewport. 1. Activate the Solview command, AutoCAD will automatically switch to PAPER SPACE (Layout1) if you are not currently in it. 2. Select the UCS option. 3. When the prompt asks for a UCS, press Enter to use the Front UCS you have already set. 4. When the prompt asks for a scale factor, type 1 (same size). 5. When the prompt indicates, click on the screen in an appropriate position for a front view. A front view of the model will appear on the screen. If the front view is not in a good location, you can click more than once until you think you have it in a good location. 6. When you have the view positioned, press Enter until the prompt directs you to "Specify first corner of viewport". 7. When asked for the first corner, click and release the LEFT mouse button in a position that would indicate one corner of a rectangular opening that would contain the model view. See Figure When the prompt directs you to "Specify opposite corner of viewport," complete the rectangular viewport by dragging your mouse to the opposite diagonal corner of the rectangle and clicking the mouse again. 9. Name it as FRONT. University Malaysia Perlis Page 68

6 Figure 4.5: Front View To place the TOP VIEW: 1. Stay in the Solview command, or return to it. 2. This time select the Ortho option. 3. Select the TOP EDGE of the FRONT viewport with the Left mouse button to indicate the "Specify side of viewport to project." See Figure 4.6. Figure Place the view in an appropriate position for a Top multiview. 5. Name the view TOP. You must click on the APPROPRIATE edge of the viewport, when using the Orthooption of this command. For example, if you click on the bottom edge of the FRONT viewport, AutoCAD will allow you to place the view in the TOP position, but University Malaysia Perlis Page 69

7 it will be a Bottom view rather than a Top view. AutoCAD uses the edges of the viewports to determine the orientation of the view in the viewport.** Now, repeat the steps using the Ortho option of Solview to create the Right Side view and name it SIDE. Look at Figure 4.7 to see how the drawing should look when you are finished. Remember to select the right edge of the Front viewport. Figure 4.7: Top, Front and Side view Your viewports do not have to match the size of those shown in Figure 4.7. Notice that the sizes of these ports vary, but the views in the viewports line up. Save your file. University Malaysia Perlis Page 70

8 To make viewport edges invisible. 1. Click the Layer Status drop-down window. 2. Scroll down to Vport layer. Vport layer contains viewport edges. 3. Click on the light bulb. The edges become invisible. See Figure 4.8. Figure 4.8: Light off VPORTS layer Notice that hidden features are seen in the views, but they are not being displayed as hidden lines. This is because you are still viewing the model in these viewports in WIREFRAME mode. The hidden lines will be created in a later step. Now, turn the Vport layer back on by again clicking on the light bulb by the Vport layer on the Layer Status drop-down menu. Step 4 Click on the Layer button to bring up the Layer Properties Manager dialogue box. Figure 4.9: Different type of layers University Malaysia Perlis Page 71

9 In this dialogue box, you should find a series of Layers labeled Front-DIM, Front-HID, Front-VIS, Side-DIM, Side-HID, etc. These layers were added by the Solview command. For now, we are only interested in the Front-HID, Side-HID, and Top-HID layers. These are assigned the Hidden line style and have their color changed. To change the color of Front-HID, for example, double click the left mouse button on the square under the property category labeled "C" (for color) in the row labeled Front-HID. The Select Color dialogue box should appear. See Figure Figure 4.10: Type of color 1. To CHANGE THE COLOR of the Front-hid layer, choose a color in the select color dialogue box by clicking on color box with the left mouse button. The new color should show in the window labeled color. 2. Stay away from the lighter shades colors, like yellow. These are difficult to see when you print. 3. Click on OK to exit the Select Color dialogue box and return to the LayerProperties Manager dialogue box. 4. Repeat this procedure for each of the layers ending in -HID (for Hidden). 5. Change the LINE THICKNESS of the -VIS layers. 6. Locate a -VIS layer and look at the setting under the Lineweight. It should be set to Default. University Malaysia Perlis Page 72

10 7. Click on the word Default and AutoCAD will open the Lineweight dialogue box. In this box, scroll down to 0.7 mm and then click on the OK button. 8. Repeat this for all of the -VIS layers. Note: Making this change will not show in the drawing until you print. If you do not make this change, the visible lines in the top-vis, side-vis, and front-vis layers would be the same thickness as the center and hidden lines. 9. Now, close the Layer dialogue window. The hidden lines in your drawing should now appear in the color you selected. 10. Finally, type SOLDRAW at command line, and type all when asked to select object. 11. Your drawing should appear like Figure 4.11 when you finish it. Figure 4.11: Hidden line appear after soldraw University Malaysia Perlis Page 73

11 STEP 5 The next step will be to add center lines to your drawing. If you need to Zoom the drawings (all three views simultaneously), you MUST be in the PAPER side of Paper Space. To check this, look at the Status Bar at the bottom of the AutoCAD screen and make sure that the word PAPER shows on the first button from the RIGHT. 1. To add center lines to the multiviews of the model, you must create three additional layers and assign the center line type to them. 2. Click the Layer button. 3. Now, ADD NEW LAYERS named: top-cen, front-cen, and side-cen. Once they are added, change the layer color assignment to something OTHER THAN BLACK and the line type to center lines. 4. Change the scale of the dashes in the hidden and center lines. Type ltscale (for Line Type Scale) at a Command: prompt and then type.25 as the new scale factor. 5. Change to Model Space. Make sure that you are in the correct layer for the view in which you are adding center lines. 6. Make sure the model is in 4 viewports. 7. Click in the Top viewport to make it the active window 8. Change to the Top-cen Layer. With the Top viewport active, you can now modify the 2D multiview projection to add center lines. The easiest method for adding the center lines is to use a combination of the Offset and Extend commands. The first center lines you should add are for the LARGE CIRCLE in the TOP view. The standard rule is that center lines should extend approximately 10 mm past the feature they are associated with if the drawing is not dimensioned. University Malaysia Perlis Page 74

12 HINT: Since you can now edit the 2D drawing in the viewports, you can use the Offset command to create a circle 10 mm larger than the original. Offset works with a circle or arc as easily as it works for a line. The Large HOLE (seen as a circle in the TOP view) has a diameter of 40, and the small HOLE (seen as a set of hidden lines on the right side of the TOP view) has a diameter of 20. Look at Figure 4.12, 4.13, 4.14 and The views show the use of the Offset, Extend, and Osnap commands to place the center lines. HINT: If you offset one of the hidden lines for the small hole center, you can move it to the Top-cen layer by selecting the line and then the top-cen layer on the LAYER STATUS WINDOW drop-down menu. Figure 4.12: Offset line by 10 mm Figure 4.13: Offset circle by 10 mm University Malaysia Perlis Page 75

13 Figure 4.14: Adding center line Figure 4.15: Adding center line NOTICE: The center lines you are placing in the Top view are also showing up in the other views. You will deal with this problem later, but it illustrates that you are seeing both the model and the 2D projections of the model in all of the viewports. See Figure University Malaysia Perlis Page 76

14 Figure 4.16: Notice other line Now, change to the side-cen layer, click in the Side viewport. In this view, the holes are shown as hidden lines. The large hole has a visible line overlapping the hidden line on its right edge. Now, create center lines for the holes in this view. See Figure Figure 4.17: View from side Finally, change to the front-cen layer, click in the Front Viewport, and add center lines to the circles in this view. NOTE: If you try to place center lines so that they extend 10 mm past the circle, they will touch the visible lines around the circle. THIS IS NOT GOOD DRAWING PRACTICE. You NEVER draw center lines so that they END at a visible line. You either shorten or lengthen the lines when this situation occurs. To deal with this problem, Offset the circle 8mm instead of 10. See Figure University Malaysia Perlis Page 77

15 Figure 4.18: Orthographic view STEP 6 We use Vplayer (Viewport Layer) to erase the extra center lines. Activate the Top viewport. Use the Freeze option under this command to "freeze" the front-cen and side-cen layers. After you exit this command, the extra center lines in this view will disappear from this view. The VIEWPORT LAYER (Vplayer) command provides control of the layers in a viewport when using multiple viewports in Paper Space. This command only works in the Model Side of Paper Space. The FREEZE option under this command allows you to make specified layers in a specific viewport invisible. Before activating the Vplayer command, you need to change to the Model Side of Paper Space. University Malaysia Perlis Page 78

16 To access the VPLAYER command, type vplayer at a Command: prompt. 1. Command: Type vplayer and Enter. 2. Enter an option [?/Freeze/Thaw/Reset/Newfrz/Vpvisdflt]: Type f for freeze. 3. Enter layer/s to freeze: Type the name of a layer or layers to freeze. 4. Enter an option [All/Select/Current] <Current>: Press Enter. 5. Enter an option [?/Freeze/Thaw/Reset/Newfrz/Vpvisdflt]: Press Enter to exit the command. Wrong Lines Disappeared The most common error that causes this problem is that the center lines were added to the wrong layers. It is easy to forget to change the layer when you shift to a new viewport and begin adding center lines. To Solve the Problems. 1. First, undo until your entire center lines show again. 2. Next, select a center line by clicking on it with the left mouse button. Look at the Layer Status Window (see sample at right). The layer that this center line was drawn on will appear in the window. 3. If the center line is not on the correct layer, use the same Layer Status Window drop-down menu to select the proper layer while the line is selected. This will move the line to the correct layer. Note: If the center line was already on the correct layer, hit Escape twice to completely deselect it before testing the next line. 4. With all the center lines now placed on the correct layers, use Vplayer again to freeze the center layers in the TOP viewport. 5. Repeat this for the Front viewport (freezing the center layers for the other viewports), and the Side viewport. HINT: You can check the name of these layers through the Layer Status Window. When completed, the drawing should look like the one in Figure University Malaysia Perlis Page 79

17 Figure 4.19: Center line from others view has been deleted Switch back to PAPER side of Paper Space and use the Layer Status Window menu to click on the light bulb icon to make the Vport layer invisible. The borders around the views will disappear, and the drawing will look like Figure Figure 4.20: Completed Orthographic Design University Malaysia Perlis Page 80