AutoCAD & AutoCAD LT All-In-One Desk Reference For Dummies (2006)

Removing stuff

Everybody makes mistakes, and now it’s time to clear away the evidence. We present the simplest-to-use of all of AutoCAD’s editing commands: ERASE. We hope it’s not your most frequently used command, but it doesn’t really matter whether it is or not — you’re not going to rub a hole in your screen by erasing AutoCAD objects.

Here are some ways to erase stuff from your drawing:

Choose Modify Erase, select the undesirables, and then press Enter.

Choose Edit Delete, select the undesirables, and then press Enter.

Click the Erase tool in the Modify toolbar, select your objects, and then press Enter.

Select the unwanted objects, choose Modify Erase, or Edit Delete, or click Erase in the Modify toolbar.

Select the mistakes and then press Delete.

Select the unwanted objects, right-click, and select Erase.

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Even the simplest commands can throw you for a loop. You may get unexpected results if you press Enter in response to the Specify Second Point prompt. Pressing Enter tells AutoCAD to look at the coordinates of the first point and use those values as the displacement for the second point. We can pretty well guarantee this is not what you want.

COPY

When you use verb-noun editing, editing in AutoCAD is much more obviously a two-step process: you select the objects, press Enter, and carry on with the command. This is a good time to show you the difference, since the MOVE and COPY commands are pretty much the same.

Choosing Modify Copy runs the COPY command, which you use for duplicating existing objects within a drawing. Choosing Edit Copy runs the Windows Copy-to-the-Clipboard command, which AutoCAD calls COPYCLIP. Use COPYCLIP to copy objects from one drawing to another. Don’t confuse the two.

Use the following steps to copy some objects using the COPY command and verb-noun editing.

1.Click the Copy button on the Modify toolbar, or choose Modify Copy, or type CO to start the Copy command.

AutoCAD prompts:

COPY

Select objects:

2. Select the objects to be copied using any object selection method.

If you choose a window or crossing, AutoCAD prompts:

Specify opposite corner: 4 found

Select objects:

3.Press Enter when you’re finished selecting objects to copy.

The first prompts for COPY are exactly the same as for MOVE. What’s different this time around is that we’re copying using verb-noun selection, and we moved using noun-verb mode. After you press Enter to finish selecting, AutoCAD prompts:

Specify base point or [Displacement] <Displacement>:

4.Pick a point on-screen as the base point.

Again, use an object snap or other precision aid if you need to. If you’re simply copying objects relative to their current location, it doesn’t

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the selected objects need to be mirrored precisely about the middle of a rectangle.

2.Hold down the Shift key and right-click to display the object snap shortcut menu. Choose Midpoint and pick a horizontal edge of the rectangle when you see the triangular object snap marker.

AutoCAD prompts:

Specify second point of mirror line:

3.Hold the Shift key and click a second point directly above or below the first point.

You need to be precise for your second point, too. Holding Shift invokes a temporary Ortho mode, when you move the crosshairs they will lock onto horizontal or vertical direction and remain that way until you release the Shift key (see Figure 2-4). AutoCAD prompts:

Erase source objects? [Yes/No] <N>:

4. Type Y or N to erase or retain the source objects.

Figure 2-4:

Mirroring objects precisely.

OFFSET

OFFSET, like COPY, makes duplicates of selected objects, but it’s more rigorous in where it lets you put those duplicates. It also doesn’t make exact copies; different object types offset in different ways. Figure 2-5 shows the results of offsetting different entity types. You can OFFSET lines, arcs, circles, splines, ellipses, and polylines.

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4. Select a single object to offset.

You can specify only one object at a time; that is, you can’t select a group of wall lines and offset them all in the same step. If you specified Through, AutoCAD prompts:

Specify through point or [Exit/Multiple/Undo] <Exit>:

For precise locations, use object snaps when picking through points. AutoCAD creates a new version of the selected object through the point you picked, and continues prompting for additional offsets and through points.

5. When you finish offsetting, press Enter to return to the command line.

If you enter a distance, you need to make an additional pick to show AutoCAD on which side of the source object you want the new object. The following steps show the process:

1. Start the OFFSET command.

The command prompts appear as follows:

Command: OFFSET

Current settings: Erase source=No Layer=Source OFFSETGAPTYPE=0

Specify offset distance or [Through/Erase/Layer] <Through>:

2.Type an offset distance value and press Enter.

AutoCAD prompts:

Select object to offset or [Exit/Undo] <Exit>:

3.Select the single object you want to offset.

Because there are two possible directions that AutoCAD could offset the selected object, it wants you to show it which direction you want by prompting:

Specify point on side to offset or [Exit/Multiple/Undo] <Exit>:

It doesn’t matter precisely where you pick, just so it’s clearly on one side or the other of the source object.

4. When you finish offsetting, press Enter to return to the command line.

Figure 2-6 shows the effect of offsetting a set of joined linework. The closed shape on the left is a single polyline, and the shape on the right is drawn as separate lines with the LINE command. For this kind of result, it’s obviously best to use a polyline rather than separate lines — you’ll end up with no intersection cleanup.

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Figure 2-6:

Offsetting polylines and lines.

Figure 2-7:

Setting a rectangular array in a dialog box.

ARRAY

COPY makes multiple copies of objects by default. If it doesn’t matter where the copies go, the COPY command is fine. However, if you need your ducks in rows (and columns, or even in a circle), the ARRAY command is for you.

ARRAY creates regular patterns of selected objects in either Rectangular (rows and columns) or Polar (circular) arrangements. The following steps explain how to create a rectangular array:

1.Choose Modify Array, click Array on the Modify toolbar, or type AR to start the ARRAY command.

The Array dialog box appears. Figure 2-7 shows the dialog configured for rectangular arrays.

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2.Make sure that the Rectangular Array radio button is selected, and then click the Select Objects button.

The dialog box closes, allowing you to select objects to array.

3.Select one or more objects to array, and then press Enter to finish selecting.

The dialog box reappears.

4.Specify the number of rows and/or columns, the row and column offsets, and (optionally) a rotation angle for the array.

If you want a single row or a single column, specify 1 in the appropriate box. Also, even though you’re making copies of a source object, the number of rows and columns must include the number of copies you want plus the source object.

You can also use the buttons beside the Row offset, Column offset, and Angle of array boxes to specify distances and angles. Clicking any of the buttons temporarily closes the dialog box and lets you pick points in the drawing.

5.Click Preview to make sure your ducks are in a row.

The main Array dialog box disappears again, and AutoCAD previews the results of your settings together with a small dialog box with buttons to Accept, Modify, or Cancel.

6.Click Accept to finish the command, or Modify to return to the dialog box, or Cancel to forget the whole business.

Choosing a polar array changes the look of the Array dialog box (see Figure 2-8). To create a polar array, you specify objects to array, and then a center point, the number of items and angle to fill, and whether the selected objects should be rotated as they’re arrayed.

Figure 2-8:

Setting up a polar array.

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