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Autocad for dummies - Byrnes D.

Byrnes D. Autocad for dummies - Wiley publishing, 2007. - 435 p.
Download (direct link): autocad2006.pdf
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6'-6" is 6 feet, 6 inches.
126 Part II: Let There Be Lines
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, 634 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 crosshairs 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.
Object snap overrides: An object snap override is active for a single pick.
^ Running object snaps: A running object snap stays in effect until you turn it off.
Here’s how you draw precise lines by using object snap overrides:
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 object snap overrides while running object snap mode is turned on, you should turn off running osnap mode while you’re getting familiar with object snap overrides. After you’ve gotten the hang of each feature separately, you can use them together.
Figure 5-12:
The object snap right-click menu.
Chapter 5: Get Ready to Draw 127
3. Start the LINE command by clicking the Line button on the Draw toolbar.
AutoCAD 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 an object snap override by clicking its toolbar button.
If you Shift+right-click, the object snap menu appears, as shown in Figure 5-12.
—*> Temporary track point Erom
Mid Between 2 Points Poinf Filters
f Endpoint / Midpoint X intersection X Apparent Intersect — Extension
© Center Q Quadrant О Tangent
_«L Perpendicular # Parallel о Node ф Insert /a Nearest fa Hone
Hj Osnap Settings...
5. Choose an object snap mode, such as Endpoint, from the object snap menu.
The object snap 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 crosshairs slowly around the drawing, pausing over various lines and other objects without clicking yet.
When you move the crosshairs near an object with an endpoint, a colored square icon appears at the endpoint, indicating that AutoCAD can
128 Part II: Let There Be Lines
snap to that point. If you stop moving the crosshairs for a moment, a 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 crosshairs around the drawing, AutoCAD no longer seeks out endpoints because object snap overrides last only for a single pick. Use the object snap right-click 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 menu, and then choose another object snap mode, such as Midpoint, from the object snap 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 crosshairs 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 crosshairs, the tooltip text reminds you what the symbol means. Figure 5-13 shows what the screen looks like during this step.
9. Draw additional line segments by picking additional points. Use the object snap right-click menu to specify a single object snap type before you pick each point.
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