OBJECTS: TO KNOW THE PROCEDURE AND USAGE OF DIFFERENT COMMANDS OF MODIFY AND LAYER TOLL BAR.
The Erase Command
Toolbar
Modify
Pull-down
ModifyErase
Keyboard
ERASE
short-cut
E
The Erase command is one of the simplest AutoCAD commands and is one of the
most used. The command erases (deletes) any selected object(s) from the drawing. Remember you can always get deleted objects back by typing U to undo, 
from the Standard toolbar or by using the OOPS command.
Command Sequence Command: ERASE
Select objects: (pick an object to erase)
Select objects: (to end the selection and erase the object)
If you simply want to erase the last object you created you can type L at the “Select objects” prompt. The last object will be highlighted and you can then select more objects orto end the command. See the “Object Selection” tutorial for more information on selecting objects.
The Copy Command
ToolbarModify
Pull-down
ModifyCopy
Keyboard
COPY
short-cut
CP
The Copy command can be used to create one or more duplicates of any drawing
object or objects which you have previously created. Copy is a very useful and time-saving command because you can create very complex drawing elements and then simply copy them as many times as you like.
Command Sequence Command: COPY
Select objects: (pick object to copy, P1) Select objects:(to end selection)
Specify base point or displacement, or [Multiple]: (pick P2 or M for multiple copies)
Specify second point of displacement or
The multiple option allows you to create additional copies of the selected object(s) by picking as many new points as you like. To end a multiple copy, just hit
thekey.
Notice that the “Base point”, P2 and the “Second point”, P3 do not have to be picked on or near the object. The two points are simply used to indicate the distance and direction of the copied object from the original object.
The Mirror Command
Toolbar
Modify
Pull-down
ModifyMirror
Keyboard
MIRROR
short-cut
MI
The Mirror command allows you to mirror selected objects in your drawing by
picking them and then defining the position of an imaginary mirror line using two points.
Command Sequence Command: MIRROR
Select objects: (pick object to mirror, P1) Select objects:(to end selection) Specify first point of mirror line: (pick P2)
Specify second point of mirror line: (pick P3)
Delete source objects? [Yes/No]
Notice that in the command sequence above, pressing thekey when asked whether to “Delete source objects?” resulted in a “No” response. This is because “No” is the default option. AutoCAD always shows the default option within triangular brackets, in this case “
In order to create perfectly horizontal or vertical mirror lines use Ortho. For more information on the use of Ortho and other drawing aids, see the “Drawing Aids” tutorial.
The Offset Command
Toolbar
Modify
Pull-down
ModifyOffset
Keyboard
OFFSET
short-cut
O
Offset is probably one of the most useful commands for constructing drawings.
The Offset command creates a new object parallel to or concentric with a selected object. The new object is drawn at a user defined distance (the offset) from the original and in a direction chosen by the user with a pick point. You can offset lines, arcs, circles, ellipses, 2D polylines, xlines, rays and planar splines.
Command Sequence Command: OFFSET
Specify offset distance or [Through] <1.0000>: 10 (specify distance) Select object to offset or
Specify point on side to offset: (pick direction, P2)
Select object to offset or
In the illustration below, a line (cyan) has been offset to the right through a distance “Offset” by picking a point to the right of the original line. The result is a new line (red) to the right of the original.
Circles can be offset inside or outside of themselves to create a new circle which is concentric (has the same centre point) with the original circle. In the illustration, a new circle (red) has been created outside of the original by picking a point outside of the original circle. The radius of the new circle is the offset distance “Offset” plus the radius of the original circle.
In the illustration above, the new objects and original objects are shown in different colours for clarity. In reality, offset objects inherit their object
properties from the original object. See the “Object Properties” tutorial for details.
The Move Command
Toolbar | Modify |  | |
Pull-down | Modify | Move | |
Keyboard | MOVE | short-cut | M |
The Move command works in a similar way to the Copy command except that no copy is made, the selected object(s) is simply moved from one location to another.
Command Sequence
Command: MOVE
Select objects: (pick object to move, P1) Select objects:(to end selection)
Specify base point or displacement: (pick P2)
Specify second point of displacement or
Note that as with the Copy command, the two pick points, P2 and P3 are used only to indicate the distance and direction of movement.
The Rotate Command
Toolbar
Modify
Pull-down
ModifyRotate
Keyboard
ROTATE
short-cut
RO
The Rotate command allows an object or objects to be rotated about a point
selected by the user. AutoCAD prompts for a second rotation point or an angle which can be typed at the keyboard.
Command Sequence
Command: ROTATE
Current positive angle in UCS: ANGDIR=counterclockwise ANGBASE=0 Select objects: (pick object to rotate, P1)
Select objects:(to end selection) Specify base point: (pick base point, P2)
Specify rotation angle or [Reference]: (pick second point, P3 or enter angle)
Remember, by default, AutoCAD angles start at 3 o’clock and increase in an anti- clockwise direction. The “ANGDIR” and “ANGBASE” variables remind you of this. If you want to rotate in a clockwise direction you can enter a negative angle by using a minus sign.
Note: You can change the angle direction and the base angle using the Units command, FormatUnits… from the pull-down menu. Click the “Clockwise” check box to change the direction and click the “Direction…” button to set the base angle.
LAYERS
