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AutCAD’s extended set of tools for working with 3D drawings lets you create 3D objects with few limitations on shape ‘and orientation. This chapter focuses on the use of these tools, which help you easily generate 3D forms and view them in both the Perspective and Orthogonal modes.

Mastering the User Coordinate System

The User Coordinate System (Ucs) allows you to define a custom coordinate system in 2D and 3D space. In fact, you’ve been using a special UCS called the World Coordinate System (WCS) all along.

By now you are familiar with the L-shaped icon in the lower-left comer of the AutoCAD screen, centaining tl<eletters W, X, and Y..The·W indicates that you are currently in the WCS; the x and Y indicate the positive directions of the x~and Y: axes. WCS is a global system of reference from which you can define other User Co.ordinate Systems .

It may help to think of these AutoCAD User Coordinate Systems as different drawing Surface 1 or two-dimensional planes. You can have several User Coordinate Systems at any given time. ,By setting up these different UCS, you are able. to draw as you would in the WCS in 2D,’yet draw a 3D image.Suppose you want to draw a house in 3D with doors and windows on each of its sides. You can set up a UCS fer each .f the sides; then you Can move from UCS to UCS to add your deers an windows. Within each of these UCSS, you draw your and windows as you would in a typical 2D drawing. You can even insert elevating views and windows that you have created in other drawings.

In this chapter you will be experimenting with a number of different views and , UCS. All of-the commands you will use are available both at the command line and via the menu bar. In addition, a number of the UCS commands can be accessed from the yes toolbar.

Defining a UCS In the first set of exercises, you will draw a chair that you can later add to your 3D Unit drawing. In drawing this chair, you will be exposed to the use of the UCS, as well as to some of the other 3D capabilities available in AutoCAD.

Begin the chair by drawing the seat and seat back.

1. Start–AutoCAD and create a new file called Barcelon.
2. Set up your drawing as an architectural drawing with a scale of 1″=1′-0″ on an 8112″ x 11″sheet. You will want to set the upper-right comer of the limits to 132 x 102. If you’re a metric user, you’ll be drawing the chair at a/Scale of 1 to 10 on ~ A4 sheet. Your work area should be 297 x 210, which is the equivalent of a 297 cm by 210 cm area.

3. Choose View> Zoom> All or type z.J A-J.
4. To draw the seat of the chair, click the Rectangle tool on the Draw toolbar, Draw a rectangle measuring 20″ in the x-axis and 30″ in the y-axis. Position the rectangle so the lower-left comer is at the coordinate 2′-0″,2′-0″.Metric users should draw a rectangle that is 50 cm by 7 with its lower-left comer at coordinate 50,50.
5. To draw the back of the chair, draw another rectangle 17″ in the x-axis and 30″ in the y-axis, just to the right of the previous rectangle. Metric users should make this rectangle 43cm by 76cm.
6. Choose View> 3D Views> SWIsometric. This gives you a 3D view from the lower-left of the rectangles, as shown.
7. Select the two rectangles, then click the Properties tool on the Standard toolbar.
8. At the Properties dialog box, enter 3 in the Thickness setting and click OK. This gives the seat and back a thickness of 3″. Metric users should make the thickness 7.6 cm.
9. Close the Properties dialog box.
10. Zoom out a bit and give yourself some room to work.

Notice that the UCS icon appears in the same plane as the current Coordinate system. The icon will help you keep track of which coordinate system you are in. Now you can see the chair components as 3D objects.

Next, you will define a UCS that is aligned with one side of the seat.

1. Right-dick any toolbar, and at the popup menu, select UCS. The UCS tool. bar appears.
2. Click the Display UCS Dialog tool in the ucs toolbar.

The UCS dialog box appears.

3. . Select the Orthographic UCSs tab to view a set of predefined UCSS.

4. Select Front in the list box. it shows the orientation of the Front ucs.
5. Click the Set Current button to make the Front UCS the current one.
6. Click OK to close the dialog box.

The Orthographic UCSS tab offers a set of predefined UCSS for each of the six. standard orthographic projection planes. These UCSs in relation to the World Coordinate System. You can also access these orthographic UCSS from the Tools :> Orthographic ucs cascading menu, or from the ucs dialog box.

Since a good part of 3D work involves drawing in these orthographic planes, AutoCAD supplies these ready-made UCS orientations for quick access. But you aren’t limited to these six orientations by any means. H you’re familiar with mechanical drafting, you’ll see that the orthographic UCS correspond to the typical orthographic projection used in mechanical drafting. H you’re an architect, the Front, Left, Back, and Right UCSs correspond to the south, west, north, and east elevations of a building. Before you continue building the chair model, you’ll want to move the UCS to the surface on which you will be working. Right now, the UCS has its origin located in the same place as the was origin. You can move a ucs so that its origin is anywhere in the drawing where it’s needed.

1. Click the Origin UCS tool in the ucs toolbar.

2. Use the Endpoint Osnap an. click the corner of the chair seat,. The ucs icon moves to indicate its new origin’s location.

The operation you just performed created a new ucs based on the Front UCS you selected from the UCS dialog box. Now as you move your cursor, you’ll see that the origin of the UCS icon corresponds to a 0,0 coordinate. Though you’ve got a new UCS, the World Coordinate still exists, and you can always return to it when you need to.

Saving a UCS

Once you’ve gone through the work of creating a UCS, you may want to save it, especially if you think you’ll want to come back to it later on. Here’s how to save a UCS.

1. Click Display UCS Dialog on the UCS toolbar. You can also choose Tools> Named UCS. The UCS dialog box appears.

2. Make sure the Named ucs tab is selected, and then highlight the Unnamed option in the Current UCS list box.

3. Right-click Unnamed, and then select Rename from the list box. The item changes to allow editing.

4. Type 3DS’ will for the name of your new ucs.

5. Click OK to exit the dialog box.

Your ucs is now saved under the name of 3DSW. You’ll be able to recall it from the ucs dialog box, or from other methods that you’ll learn about later in this chapter.

Working in a UCS

Next, you will want to arrange the seat and back and draw the legs of the chair . Your ucs is oriented so that you can easily adjust the orientation of the chair components to their proper orientation. As you work through the next exercise, notice that while you are manipulating 3D objects, you are really using the same tools you’ve used to edit 2D objects.

1. Click the seat back to expose its grips.

2. Click the bottom grip, as shown.

3. Right-dick the mouse to open the Grip Edit popup menu.

4. Select Rotate from the menu. Notice how the seat back now rotates with the movement of the cursor. Take a moment to play with this rotation, as it may take a while to grow accustomed to it. Since this is an Isometric view, you can get an optical illusion effect.

5. Type 80↵ to rotate the seat back 80°.

6. Click the bottom grip shown.

7. Right-dick the mouse again and select Move.

8. Using the Endpoint Osnap, dick the top comer of the chair seat, as shown, to join the chair back to the seat.

9. < Click both the chair seat and back; then click the bottom-comer grip of the seat, as shown.

10. Right-click the mouse; then at the Grip Edit popup menu, click Rotate.

it Enter -10↵ to rotate both the seat and back a minus 10 degrees. Press the Esc key twice to dear the grips.

. The new UCS orientation enabled you to use the grips to adjust the chair seat and back. All of the grip rotation in the previous exercise was confined to the plane of the new UCS. Mirroring and scaling will also occur in relation to the current UCS.

Now to finish the chair seat and back, add a 3D Face to their top and bottom surfaces.

1. To help you visualize what’s going on as you add the 3D Face, turn on the Hidden Shade mode by choosing View >- Shade >- Hidden. Or, if you have the Shade toolbar open, you can click the Hidden tool.

2. Click the 3D Face button on the Surfaces toolbar, or choose Draw >- Surfaces >- 3D Face, to draw a surface over the top sides of the chair seat and back. Start the 3D Face in the leftmost comer of the seat and work in a counterclockwise fashion.

3. . Add the 3D Faces to the bottom of the chair seat and to the chair back, as shown.

4. When you’ve finished adding the 3D Faces, turn off the Hidden Shade mode. Choose View >- Shade >- 20 Wireframe .

Normally, when picking points for 30 Faces, it doesn’t matter where you start selecting points. But fur the purpose of this tutorial. you selected points for the seat’s 3D Face starting at the leftmost comer and working in a counterclockwise fashion. The way you create the chair seat will influence the action of some ucs command options which you’ll use later in this chapter.

Using Viewports to Aid in 3D Drawing

you-were introduced to AutoCAD’s floating viewports in Paper Space. In this section, you will use tiled viewports to see your 3D model from several sides at the same time. This is helpful in both creating and editing 3D drawings because it allows you to refer to different portions of the drawing without having to change views. Tiled viewports are created directly in Model Space .

1. Select View >- Viewports >- Named Viewports. The Named View ports dialog box appears.

2. Make sure the New Viewports tab is selected, then click Three: Right from the Standard Viewports list on the left. The window on the right changes to displaya sample of the viewport configuration. It shows three rectangles, which represent the viewports, arranged with two on the left and one larger one to the right. Notice that each rectangle is labeled as Current. This tells you that the current view will be placed in each viewport.

3. Open the Setup drop-d.own list at the bottom of the dialog box and select 3D. Now notice that the labels in the viewport sample change to indicate Top, Front, and SE Isometric. This is close to the arrangement that you’ll want, but you need to make one more adjustment. The viewport to the right, SE Isometric, shows the backside of the chair. You want an SW Isometric view in this . window .

4. Click the SE Isometric viewport sample. Notice that the sample viewport border thickens to indicate that it is selected.

5. Open the Change View To drop-down list just below the sample viewports and select SW Isometric. The label in the selected viewport changes to let you know that the view will now contain the SW Isometric view. Notice that the list contains the standard four isometric views and the six orthogonal views. By clicking a sample viewport and selecting an option from the Change View To drop-down list, you can arrange your viewport views in nearly any way you want.

6. To keep this viewport arrangement, enter My Viewport Setup in the New Name in out box.

7. Now click OK. Your display changes to show three viewports arranged as they . were indicated in the Viewports dialog box.

8. To check to see that your viewport was saved, Choose View >Viewports >- Named Viewports to open the Viewports dialog box again.

9. Click the Named Viewports tab. My Viewport Setup is listed in the Named Viewports list box. If you dick it, a sample view of your viewport arrangement appears on the right.

10. After you’ve reviewed the addition to the Named Viewports list, close the dialog box,

Now take a close look at your viewport setup. Notice that the UCS icon in each of the two orthogonal views in the two left viewports are oriented to the plane of the view. AutoCAD allows you to set up a different UCS for each viewport. The top view uses the WCS since it is in the same plane as the WCS. The side view has its own UCS, which is parallel to its view. The isometric view to the right retains the UCS you saved-namely the 3DSW UCS.

Another Viewports dialog box option you didn’t try is the Apply To drop-down list in the New Viewports tab of the Viewports dialog box.

This list shows two options: Display and Current Viewport. When Display is selected, the option you choose from the Standard Viewports list applies to the over all display. When Current Viewport is selected, the option you select applies to the selected viewport in the sample view in the right side of the dialog box. You can use the Current Viewport option to build multiple viewports in custom arrangements.

Adding the Legs

The next items you will add to your chair are the legs. Before you do that, you’ll want to set up the 3DSW ucs in the side view of your chair.

1. Click the lower-left viewport to make it active.
2. Click the Display ues Dialog tool on the ues toolbar.
3. Select the Named uess tab, then select 3DSW from the list of uess.
4. Click the Set Current button. The triangular marker to the left of the ues names moves to 3DSW.
5. Click OK.

Now you’re ready to draw the legs using the coordinate information shown.

Now let’s finish off the chair by adding legs.

1. Go to the side view of the chair and move the chair seat and back vertically in the y-axis 8.5″ or 21.6 cm for metric users. Make sure you select all the lines and 3D Faces for the move. You may have to pan the view don so that the entire chair is displayed.

2. Next, draw two curved poly lines, as shown in Figure 16.9. You may have to adjust your view so that you can draw the legs more easily. You don’t have to be absolutely perfect about placing or shaping these lines.

3. Use the grips of the poly lines to adjust their curve, if necessary.

4. Use Modify> Poly line to give the poly lines a width of 0.5″ (1.27 cm for metric users).

5. Use the Properties dialog box to give ,the poly lines a thickness of -2″ (minus 2 inches). Metric users should make.the thickness -5cm. Notice that as you draw and edit a poly line, it appears in both the Plan and 3D views.

6. Close the Properties dialog box when you are done changing the thickness property.

7. Click the top view of the chair in the upper-left viewport.

8. Turn the Ortho mode on, and then click the Mirror tool on the Modify toolbar.

9. In the upper-left viewport, click the two polylines representing the chair legs, then press ↵.

10. At the First point of mirror line: prompt, use the Midpoint Osnap and select the midpoint of the chair seat, as shown.

11. At the second point, pick any location to the right of the point you selected, so that the rubber-banding line is exactly horizontal.

12. Press ↵ at the Delete old object: prompt. The legs are mirrored to the opposite side of the chair. Your screen should look similar.

Your chair is now complete. Let’s finish up by getting a better look at it.

1. Click the viewport to the right showing the isometric view.

2. Open the Viewport dialog box and select the New Viewport tab.

3. Select Single from the Standard Viewports list, and then click OK.

4. Choose View ~ Hide to get a view of your chair with the lines hidden, as shown.

Controlling the UCS You’ve seen how you can select a ucs from a set of predefined. UCSS. You can frequently use these preset ucss and make minor adjustments to them to get the exact ucs you want.

There are also a number of other ways to define a ucs. You can, for example, use the 3D Face of your chair seat as the definition for a ucs. In the following set of exercises, you will get some practice moving your ucs around. Learning how to move effortlessly between ucss is crucial to your mastering the creation of 3D models, so you’ll want to pay special attention to the command options shown in these procedures. These options are accessible from either the Tools> ucs cascading menu or the UCS toolbar.

UCS Based on Object Orientation

You can define a ucs based on the orientation of an object. This is helpful when you want to work on a predefined object to fill in detail on its surface plane.

1. Click the Object ucs tool on the UCS toolbar, or choose Tools > New ucs :> Object. You can also type ucs↵ OB↵.

2. At the Select object to align UCS: prompt, pick the 3D Face used to define the top surface of the chair seat. Because the 3D Face and the poly line outline of the seat share a common edge, you may need to use the Selection Cycling feature to pick the 3D Face. The ucs icon shifts to reflect the new coordinate system’s orientation.

Orientation of the UCS Origin Remember earlier in the chapter when you drew the 3D Face for the seat in a specific way? Well, the location of the ucs origin and its orientation depend on how that 3D Face was created. If you had drawn it other than as instructed, the ucs you defined using the Object option in the above exercise would not have been generated as described.

Table describes how an object can determine the orientation of a ucs.

UCS Based on Offset Orientation

There may be times when you want to work in a ucs that has the same orientation as the current ucs but is offset. For example, you may be making a drawing of a building that has several parallel walls offset with a saw tooth effect.You can easily hop from one ucs to another parallel ucs by using the Origin option.

1. Click the Origin ucs tool on the ucs toolbar, or choose Tools >-New ucs>- Origin. You can also type ucs↵ O↵.

2. At the Origin point <0,0,0>: prompt, pick the bottom end of the chair leg, just below the current ucs origin. The ucs icon shifts to the end of the leg, with its origin at the point you picked.

Moving vs. Creating a UCS Origin

The Origin ucs tool creates a new ucs that you can save under its own name. Another option that is very similar to the Origin ucs tool is the Move ucs option on the Tools pull-down menu. At first glance, they seem to do the same thing, that is, create a new ucs by moving an existing ucss origin. There is a subtle difference between the two, however. The Tools >- Move ucs option is intended to move an
existing named ucs to a new location. It doesn’t actually create a new one. For example, if you use Move ucs to move the 3DSW ucs you created earlier in this chapter, then when you recall 3DSW, it will appear in its new location. On the other hand, if you use the Origin ucs tool to change the origin of the 3DSW ucs, AutoCAD creates an entirely different ucs and maintains the original location of 3DSW.

The Tools >- Move ucs option can also be found on the ucs IT toolbar. You’ll get a chance to work with the ucs II toolbar in the next section.

UCS Rotated Around an Axis

Now suppose you want to’change the orientation of the X-, y-, or z-axis of a ucs. You can accomplish this by using the X,Y,or Z Axis Rotate ucs options on the ucs toolbar. Let’s try rotating the ucs about the z-axis to see how this works.

1. Click the Z Axis Rotate ucs tool on the ucs toolbar, or choose Tools >- New ucs >- Z Axis Rotate. You can also type ucs↵ Z↵. This will allow you to rotate the current ucs around the z-axis,

2. At the Rotation angle about Z ax; 5 <0>: prompt, enter 90 for 90°. The ucs icon rotates to reflect the new orientation of the current ucs.

Similarly, the X and Y Axis Rotate ucs options allow you to rotate the ucs about the current x- and y-axis, respectively, just as you did for the z-axis above. The X and Y Axis Rotate ucs tools are very helpful in orienting a ucs to an inclined plane. For example, if you want to work on a plane of a sloped roof of a building, you can first use the Origin ucs tool to align the ucs to the edge of a roof and then use the X Axis Rotate ucs tool to rotate the ucs to the angle of the roof,slope, as shown.

Finally, you can skew the UCS using the Z Axis Vector option. This is useful when you need to define a UCS based on a z-axis determined by two objects .

1. Click the Z Axis Vector ucs tool on the ucs toolbar, or choose Tools >ucs l>: Z Axis Vector, You can also type UCS↵ ZA↵:

2. At the Origin point <0.0.0>: prompt, press ↵ to accept the default, which is the current ucs origin. You can shift the origin point at this prompt if you like.

3. At the next prompt:

Point on positive portion of Z-axis <0′-0′, 0′- 0′, 0′-1′>:

use the Endpoint Osnap override and pick the other chair leg end, as shown. The ucs twists to reflect the new z-axis of the ucs.

Orienting a UCS in the View Plan

Finally, you can define a ucs in the current view plane. This is useful if you want to switch quickly to the current view plane for editing or for adding text to a 3D view.

Click the View ucs tool 011 the ucs toolbar, or choose View >Set ucs :> View. You can also type UCS↵ V↵. The ucs icon changes to show that the ucs is aligned with the current view.

AutoCAD uses the current UCS origin point for the origin of the new UCS. By defining a view as a UCS, you can enter text to label your drawing, just as you would in a technical illustration. Text entered in a plane created in this way appears normal.

Now you’ve finished your tour of the UCS command. Set the VCS back to the World Coordinate System and save the Barcelon. dwg file.

You’ve explored nearly every option in creating a UCS, except for one. In the text section, you’ll learn about the 3 Point option for creating a UCS. The 3 Point option is the most versatile method for creating a UCS, but it is a bit more involved than some of the other UCS options.

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