AutoCAD 2005 for Dummies

  You can view coordinate locations by moving the cursor around in the drawing area and reading the Coordinates area at the left of the status bar. The X,Y coordinates should change as you move the cursor. If the coordinates don’t change, click the Coordinates area until the command line says <Coords on>. Although it’s not apparent at first, there are in fact two <Coords on> display modes: absolute coordinates and polar coordinates. If you start a command such as LINE, pick a point, and then click the Coordinates area a few times, the display changes from coordinates off to live absolute coordinates (X,Y position) to live polar coordinates (distance and angle from the previous point). The live polar coordinates display mode is the most informative most of the time.

  When you type coordinates at the command line, do not add any spaces, because AutoCAD interprets them as though you’ve pressed Enter. This “Spacebar=Enter” weirdness is a productivity feature that’s been in AutoCAD forever. It’s easier to find the spacebar than the Enter key when you’re entering lots of commands and coordinates in a hurry.

  If you’re working in architectural or engineering units, the default unit of entry is inches, not feet.

? To specify feet, you must enter the symbol for feet after the number, for example:

6’ for 6 feet

? You can enter a dash to separate feet from inches, as architects often do:

6’–6” is 6 feet, 6 inches.

? Both the dash and the inch mark are optional when you’re entering coordinates and distances:

AutoCAD understands 6’6” and 6’6 as the same as 6’– 6”.

? If you’re typing a coordinate or distance that contains fractional inches, you must enter a dash — not a space — between the whole number of inches and the fraction:

6’6–1/2 (or 6’–6–1/2) represents 6 feet, 6? inches.

? If all this dashing about confuses you, enter partial inches by using decimals instead:

6’6.5 is the same as 6’6–1/2 to AutoCAD, whether you’re working in architectural or engineering units.

Grab an object and make it snappy

After you’ve drawn a few objects precisely in a new drawing, the most efficient way to draw more objects with equal precision is to grab points, such as endpoints, midpoints, or quadrants, on the existing objects. AutoCAD calls this object snapping, because the program pulls, or snaps, the cursor to a point on an existing object. The object snapping feature in general and object snap points in particular often are called osnaps.

I’d like to make just one point

AutoCAD provides two kinds of object snapping modes:

? Single point (or override) object snaps

A single point object snap lasts just while you pick one point.

? Running object snaps

A running object snap stays in effect until you turn it off.

Here’s how you draw precise lines by using single point object snaps: 

1. Open a drawing containing some geometry.

2. Turn off running osnap mode by clicking the OSNAP button on the status bar until the button appears to be pushed out and the words <Osnap off> appear on the command line.

  Although you can use single point object snaps while running object snap mode is turned on, you should turn off running osnap mode while you’re getting familiar with single point object snaps. After you’ve gotten the hang of each feature separately, you can use them together. 

3. Start the LINE command by clicking the Line button on the Draw toolbar.

The command line prompts you to select the first endpoint of the line:

Specify first point:

4. Hold down the Shift key, right-click anywhere in the drawing area, and release the Shift key.

  If you find the Shift+right-click sequence awkward, you can avoid it by using the Object Snap toolbar instead. To turn the toolbar on, point to any toolbar button, right-click, and choose Object Snap. Now you can activate a single point object snap by clicking its toolbar button. The object snap cursor menu appears, as shown in Figure 4-11.

Figure 4-11: The object snap cursor menu.  

5. Choose an object snap mode, such as Endpoint, from the object snap cursor menu.

The object snap cursor menu disappears, and the command line displays an additional prompt indicating that you’ve directed AutoCAD to seek out, for example, endpoints of existing objects:

_endp of:

6. Move the cursor slowly around the drawing, pausing over various lines and other objects without clicking yet.

When you move the cursor near an object with an endpoint, a colored square icon appears at the endpoint, indicating that AutoCAD can snap to that point. If you stop moving the cursor for a moment, a yellow ToolTip displaying the object snap mode (for example, Endpoint) appears to reinforce the idea.

7. When the endpoint object snap square appears on the point you want to snap to, click.

AutoCAD snaps to the endpoint, which becomes the first point of the new line segment that you’re about to draw. The command line prompts you to select the other endpoint of the new line segment:

Specify next point or [Undo]:

When you move the cursor around the drawing, AutoCAD no longer seeks out endpoints because single point object snaps last only for a single pick. Use the object snap cursor menu again to snap the other end of your new line segment to another point on an existing object.

8. Use the “press Shift, right-click, release Shift” sequence described in Step 4 to display the object snap cursor menu, and then choose another object snap mode, such as Midpoint, from the object snap cursor menu.

The command line displays an additional prompt indicating that you’ve directed AutoCAD to seek, for example, midpoints of existing objects:

_mid of:

When you move the cursor near the midpoint of an object, a colored triangle appears at the snap point. Each object snap type (endpoint, midpoint, intersection, and so on) displays a different symbol. If you stop moving the cursor, the ToolTip text reminds you what the symbol means. Figure 4-12 shows what the screen looks like during this step.

Figure 4-12: A snappy line.

9. Draw additional line segments by picking additional points. Use the object snap cursor menu to specify a single object snap type before you pick each point.

Try the Intersection, Perpendicular, and Nearest object snaps. If your drawing contains arcs or circles, try Center and Quadrant.

10. When you’re finished experimenting with single point object snaps, right-click anywhere in the drawing area and choose Enter from the cursor menu.

  There’s a difference between right-clicking and Shift+right-clicking in the