Chapter 8 Viewing Your Drawing 163
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Figure 8-20: Using a customized UCS to start to draw a detail for a drill.
11.To return to the Rotated 45 UCS, choose Tools Named UCS to open the UCS dialog box. Choose Rotated 45 and click Set Current. Click OK to restore the Rotated 45 UCS.
12.Save your drawing.
Tip |
After creating a new, rotated UCS such as the one in the previous exercise, type plan (to start |
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the PLAN command) and use the Current UCS option to remove the rotation. Now you aren’t |
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working at an angle in your UCS. To return to the World UCS, type plan again and choose the |
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World option to return to your drawing’s previous state. |
Creating Isometric Drawings
An isometric drawing is a 2D drawing made to look like a 3D drawing. Every child learns how to draw a box that looks three-dimensional. By drawing parallelograms instead of squares, the drawing gives the impression of being in three dimensions. AutoCAD and AutoCAD LT enable you to do the same thing.
Understanding isometric planes
The ISOPLANE (short for isometric plane) command rotates the crosshairs to the special angles required for isometric drawing. You then toggle the ISOPLANE setting from left to right to top, to draw on each of the three “planes.” As you do so, the angles of the crosshairs, snap, and grid change to the appropriate angles.
These angles are 30 degrees for the X axis, 90 degrees for the Z axis, and 150 degrees for the Y axis. As you toggle among the planes, you see the crosshairs take on various configurations of these angles. Figure 8-21 shows the standard isometric cube. You can see three sides — left, right, and top. In the figure, the crosshairs are set to the right isometric plane.
164 Part II Drawing in Two Dimensions
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Isometric drawing is not often used for precise drawing because specifying the exact points |
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that you need, can be difficult. Also, true 3D drawing has mostly supplanted isometric drawing. |
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It is, however, used for piping work as well as for illustrations. |
Tip |
Use snap points and object snaps as much as possible in an isometric drawing. Also, set the |
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cursor to 100 percent of the screen to better visualize the isometric planes. (Choose Tools |
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Options and click the Display tab.) The grid is also a helpful aid. |
Left plane Top plane Right plane
y axis x axis
Figure 8-21: The isometric cube.
Drawing in Isometric mode
To start Isometric mode, choose Tools Drafting Settings to open the Drafting Settings dialog box. On the Snap and Grid tab, in the Snap Type & Style section, choose Grid Snap (if it is not already selected), and then Isometric Snap. While you’re there, turn on Snap and Grid if you want them on. Click OK. After you’re in Isometric mode, press F5 to toggle from plane to plane.
Drawing lines in Isometric mode is fairly straightforward if the lines are parallel to one of the isometric plane angles. Circles and arcs in Isometric mode must be drawn as ellipses and elliptical arcs. When you’re in Isometric mode, the ELLIPSE command has an Isocircle option.
STEPS: Drawing in Isometric Mode
1.Start a new drawing by using the acad.dwt or aclt.dwt template.
2.Save the drawing in your AutoCAD Bible folder as ab08-04.dwg.
3.Right-click the SNAP button on the status bar and choose Settings. On the Snap and Grid tab, in the Snap Type & Style section, choose Grid Snap (if it is not already selected), and then Isometric Snap.
4.In the Snap section, ensure that the Snap Y spacing is set to 0.5 and click Snap On. In the Grid section, ensure that the Grid Y spacing is set to 0.5 and click Grid On. Click OK to return to your drawing.
Chapter 8 Viewing Your Drawing 165
5.Choose Tools Options and click the Display tab. In the Crosshair Size text box, change the cursor size to 100. Click OK.
6.Press F5 until you see the <Isoplane Left> prompt.
7.Do a Zoom All to zoom into the area covered by the grid.
8.Start the LINE command. Follow the prompts:
Specify first point: Use the coordinate display to choose 3.4641,2, which is a snap point. (It may take you a while to find the point.) Specify next point or [Undo]: Choose 6.4952,0.25. (Press F6 if necessary to get dynamic absolute coordinates.)
Specify next point or [Undo]: Choose 6.4952,1.25. Specify next point or [Close/Undo]: Choose 3.4641,3.
Specify next point or [Close/Undo]: Right-click and choose Close to close the left side of the model. All of these points are snap points.
The results are shown in Figure 8-22.
Figure 8-22: The left side of the iron plate. The cursor has been changed to extend to 100 percent of the screen.
9.Press F5 twice until you see <Isoplane Right> on the command line.
10.Start the LINE command again. Follow the prompts:
Specify first point: Pick 6.4952,1.25. Press F6 twice to get dynamic polar coordinates.
Specify next point or [Undo]: Pick when the coordinates show 2.0000<30.
166 Part II Drawing in Two Dimensions
Specify next point or [Undo]: Use the polar coordinate display to draw a line of 1.0000<270.
Specify next point or [Close/Undo]:Draw a line of 2.0000<210. Specify next point or [Close/Undo]:
11.Press F5 twice until you see <Isoplane Top> on the command line.
12.Start the LINE command. Start the line at 8.2272,2.25, which is a snap point. Draw a line of 3.500<150 and continue another line of 2.000<210. End the LINE command. This completes the box.
13.Choose Ellipse from the Draw toolbar. Right-click and choose Isocircle from the shortcut
menu. At the Specify center of isocircle: prompt, choose 5.1962,3. At the Specify radius of isocircle or [Diameter]: prompt, type .5 to draw the ellipse. Your drawing should look like Figure 8-23.
14.Change the cursor size back to 5 (%). Save your drawing.
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Figure 8-23: The completed iron plate with a hole in it, |
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drawn isometrically. |
Tip |
Polar coordinate display is very helpful while drawing isometrically. The coordinates are easier |
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to understand than the unusual absolute snap point coordinates created by ISOPLANE. |