ىلولاا ةلحرملا · 1. SNAP (F9 or status bar) Snap has two modes in AutoCAD: 1- Grid SNAP. 2- Polar SNAP. *Grid snap is a function that forces the cursor to “snap”

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Department of Computer Engineering& Information Technology

قسم هندسه الحاسبات و تكنلوجيا المعلومات

المرحلة االولى

Lecture (1)

Drawing by AutoCAD

Issued by Assistant Lecturer

Ameer Mosa Thoeny

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Drawing by AutoCAD

The CAD data base:

A CAD (Computer Aided Design) file, which is the

electronically stored version of the drawing, keeps data in

binary digital form. These digits describe coordinate values

for all of the end points, center points, vertices, etc. for all

the objects composing the drawing, along with another

code that describes the kinds of objects (line, circle, arc,

ellipse, etc.).

Graphics Area:

The large central area of the screen is the Graphics

area. It displays the lines, circles, and other objects you

draw that will make up the drawing.

The cursor is the intersection of the crosshairs (vertical and

horizontal lines that follow the mouse or puck movements).

The default size of the graphics area for English settings is

12 units (x or horizontal) by 9 units (for vertical).this

usable drawing area (12*9) is called the drawing limits and

can be changed to any size to fit the application. As you

move the cursor, you will notice the numbers in the

coordinate display change.

Command Line:

The command line consist of the three text lines at the

bottom of the screen (by default) and is the most important

area other than the drawing itself. Any command that is

entered or any prompt that Auto CAD issues appear here.

The command line is always visible and gives the current

state of drawing activity.

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Tool bars:

AutoCAD provides a variety of tool bars. Each toolbar

contains a number of icon buttons (tools) that can be picked

to invoke commands for drawing or editing objects (lines,

arcs, circle, etc.) or for managing files and other functions.

*The standard toolbar is the row of icons nears the top of

the screen. The standard toolbar contains many standard

icons used in other windows applications ( like New, Open,

Save, Print, Cut, Paste, etc.) and other icons for AutoCAD

specific functions (like Zoom and Pan).

*The object properties toolbar located beneath the standard

toolbar is used for managing properties of objects, such as

layers and types.

*The draw and modify toolbar also appear (by default)

when you first use AutoCAD. The draw and modify

toolbars (side) and the standard and object properties

toolbar (top) are docked.

*The status bar is a set of informative words or symbols

that gives the status of the drawing aids. The status bar

appears at the very bottom of the screen. The following

drawing aids can be toggled on or off by single clicking

(pressing the left mouse button once) on the desired word

or by using function keys.

*The following drawing aids are listed below

SNAP, GRID, ORTHO, POLAR, OSNAP, and

MODEL.

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Drawing Aids:

1. SNAP (F9 or status bar)

Snap has two modes in AutoCAD:

1- Grid SNAP.

2- Polar SNAP.

*Grid snap is a function that forces the cursor to “snap” to

regular interval (0.5 units is the default English setting)

which aids in creating geometry accurate to interval lengths.

You can use the snap command or the drafting setting

dialog box to specify any value for the grid snap increment.

*Polar snap forces the curser to snap to regular interval

along angular lines.

Since you can have only one snap mode on at a time (grid

snap or polar snap), you can select which of two is on by

right-clicking on the word, SNAP on the Status bar.

2. Grid (F7 or status bar)

A drawing aid called Grid can be used to give a visual

reference of units of length. The GRID default value

for English settings is 0.5 units. The GRID command

or drawing Aids dialog box allows you to change the

interval to any value.

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3. ORTHO If ORTHO is on, lines are forced to an orthogonal alignment

(horizontal or vertical). ORTHO can be turned only on or off.

4. Object SNAP MODES:

AutoCAD provides the following object snap modes.

1) Center

This OSNAP option finds the center of a circle, Arc, or

Dount.

2) End point

The End point option snap to the end point of a line, pline,

spline, or Arc.

3) Intersection

Using this option causes AutoCAD to calculate and snap to

the intersection of any two objects.

4) Mid point

The midpoint option snaps to the point of a line or arc that

half way between the end points.

5) Insert

6) Perpendicular

7) Nearest

8) Node

9) Tangent

This option calculates and snaps to a tangent point of an Arc

or circle.

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SETUP COMMANDS:

1-units command:

The units command allows you to specify the type and

precision of linear and angular units as well as the direction

and orientation of angles to be used in the drawing. There

are five types of units:

1. Scientific.

2. Decimal.

3. Engineering.

4. Architectural.

5. Fractional.

• There are two ways to execute it:

A. Menu bar ….> Format ….> Units.

B. Command line: Units

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2-LIMITS Command:

The limits command allows you to set the size of the

drawing area by specifying the lower-left and upper-right

corners in x,y coordinate values. Limits also define the

display area for GRID as well as the minimum area

displayed when a Zoom All is used.

• There are many ways to execute it:

A. Menu bar ….. > Format ……> Drawing limits.

B. Command line: limits

Specify lower left corner or [ON/OFF] <0.000, 0.000>:x,y

Specify upper right corner<12.0000, 9.0000>:x,y

3-Zoom Command:

The ZOOM command enables you to zoom in and out of your drawing, like

the zoom lens of camera. When you zoom in, everything is magnified so that

you can see it more easily, but you see less of the entire drawing. When you

zoom out, objects look smaller, but you can see more of the drawing. The

ZOOM command has several options that make it easy to see just what you

need at an appropriate size.

Note: Zooming does not affect the actual size of objects, just as zooming

with a camera lens does not affect the size of the scene you‟re viewing.

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• There are many ways to execute it:

A. Menu bar ….. > view ……> zoom.

B. Command line: zoom

Specify corner of window, enter a scale factor (nX or nXP), or [All/Center/Dynamic/Extents/Previous/Scale/Window] <Real time>: 2x

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Exercises:

Q1: Create a new drawing with the following settings:

1) You will use decimal units on your drawings.

2) Set up for a sheet of 300,220.

3) Set the values of grid and snap to 20.

4) Save the project as (shapes-dwg).

Q2: Start a new drawing set it up as follows:

1) Units: architectural.

2) Lower left limits:0,0.

3) Upper right limits:17:11.

4) Grid:1/2.

5) Snap:1/4.

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Lecture (2)

Layer


Ameer Mosa Thoeny

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Organizing Drawings with Layers, Colors, Linetypes, and Lineweights

Until now, we have drawn everything in black or white.

Drawing everything in one color is not a very good way to draw —

besides, it‟s boring! If everything is the same color and same line-

types, it‟s hard to distinguish the various elements of a drawing.

So with complex drawing we need to use various properties like

multicolor or multi linetype such as (continues or dashed lines) or

multi linewight such as (0.5, 0.9 or 1.3 mm) to help to organize our

drawings, making them easier to understand...

Most often, we assign color, linetype, and lineweight to a layer.

A Layer: is simply an organizational tool that lets you organize

the display of objects in our drawing.

Every object must have a layer, and every layer must have a color,

a linetype, and a lineweight.

We define layers to meet our drawing needs. Layers, colors,

linetypes, and lineweights are called object properties.

Layers give us many ways to organize your drawing. For example, we can:

✦ Assign different colors, linetypes, and lineweights to layers.

✦ Control the visibility of layers. Making a layer invisible lets us focus on

just the objects that we need to draw or edit.

✦ Control which objects are plotted.

✦ Lock a layer so that objects on that layer cannot be edited.

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Creating new layers

To create a new layer, choose Layer Properties Manager because it

is the best way to gain complete layer control. The layer properties

manager is invoked by using:

1. The icon button in properties toolbar.

2. Selecting layer from the format pull down or screen menu.

3. Typing the layer command.

New layers can be created by selecting the new button near the

upper right corner of the dialog box.

The command line format of layer shows all of the available

options.

Command: layer

Current layer: „0‟

[set /new/on/off/color/lweight/ltype/freez/lock]

The Layer Properties Manager dialog box opens, as shown:

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Columns in the Layer Properties Manager

Using layers We must know the meaning of each property to use it in effective

way, which is the same in properties toolbar or layer command

options, so we will explain it as shown below:

OR

Command: layer

Current layer: „0‟

[set /new/on/off/color/lweight/ltype/freez/lock]

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Current or Set: To set a layer as the current layer is to make it the active

drawing layer. Any objects created with draw command are

created on the current layer.

You can edit objects on any layer, but draw only on the current

layer.

Any layer can be can be mode current, but only one layer at a

time can be current.

To set the current layer with the layer properties manager, select

the desired layer from the list and then select the current tile.

ON,OFF: If a layer is on, it is visible. Object on visible layer can be edited

or plotted. Layer that are off are not visible. Objects on layers

that are off will not plot and cannot be edited. It is not advisable

to turn the current layer off.

Freeze: Freeze is amore protected state than off. Like being off, a frozen

layers not visible, nor can it is objects be edited or plotted.

Lock ,Unlock: Layer that are locked are protected from being edited but are

still visible and can be plotted.

Locking a layer prevents it is objects from being changed even

though they are visible. Layer can be locked and off.

Color: Selecting one of the small color boxes in the list area of the

layer properties manager causes the select color dialog box top

up. The desired color then can be selected.

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Line type: To set line type, select the line type (word such as continuous or

hidden) in the layer list, which in turn invokes the select line

type dialog box. Select the desired line type from the list.

Line weight: The line weight for a layer can be set by selecting the line

weight (word such as default or 0.20mm, 0.50mm, 0.010 “or

0.020”, etc.) in the layer list.

Exercise:

A. Begin a new a drawing. Set limits to 11*8.5, then zoom all.

Use the line type manager to list the loaded line types. Are

any line types already loaded? Pick the load button.

B. Use the layer properties manager to create 3 new layers

named OBJ, HID, and CEN. Assign the following colors, line

types, and line weights to the layers by clicking on the color,

line type, and line weight columns.

OBJ RED Continuous Default

HID Yellow Hidden Default

CEN Green Center Default

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Lecture (3) Coordinates entry methods, line and display coordinate


Ameer Mosa Thoeny

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The four coordinates entry methods:

All drawing commands prompt you to specify points

or locations, in the drawing. For example, the line

command prompts you to give the “specify first point” and

“specify next point” excepting you to specify locations for

the first and the second end points of the line. After you

specify these points, AutoCAD stores the coordinate values

to define the line. A two-dimensional line in AutoCAD is

defined and stored in the default base as two sets of X,Y

and Z values (with Z values of 0), one for each point.

There are four ways to specify coordinate:

1. Interactive method.

2. Absolute coordinates.

3. Relative rectangular coordinates.

4. Relative polar coordinates.

*Interactive method:

Use the cursor to select points on the screen. (Pick)

*Absolute method:

Absolute coordinates are used when AutoCAD

prompts for a point and you know the exact coordinates of

the desired location. You simply key in the coordinate

values at the key board (X and Y values are separated by a

comma).

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*Relative rectangular method:

Relative rectangular coordinates are similar to

absolute values except the X and Y distances are given in

relation to the last point, instead of being relative to the

origin.

AutoCAD interprets the @ symbol as the “last point”. Use

this type of coordinate entry when you do not know the

exact absolute values, but you know the X and Y distances

from the last specified point.

*Relative polar Rectangular:

Relative polar rectangular entry is often used when

you want to draw a line or specify a point that is at an exact

angle with respect to the last point. Interactive coordinate

entry is not accurate enough to draw diagonal lines to a

specified angle AutoCAD interprets the @ symbol as last

point and the <symbol as an angular designator for the

following value. So@ 2<45 “means from the last point, 2

units at an angle of 45 degrees”.

Drawing Commands

1. Line:

This is the fundamental drawing command. The line

command creates straight line segments; each segment

is an object. One or several line segments can be

drawn with the line command.

Command: Line

Specify first point: Pick

Specify next point: Pick

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Specify next point: Pick

Specify next point: Press enter to finish command.

Command:

Example:

1) Draw a horizontal line of 2 units length starting at

point 2,3 using absolute coordinates.

Command : L

Specify first point: 2,3

Specify next point: 4,3


point 2,4 using relative coordinates.

Command: L


Specify next point: @2,0


point 2,5 using relative polar coordinates.

Command: L


Specify next point: @2<0

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Displaying Coordinates As you work, you can refer to the coordinate display on

the status bar. This display helps you know where your cursor

and objects are when you draw and is also helpful when editing,

by informing you how far and in what direction you are

moving or copying objects.

AutoCAD and AutoCAD LT have three coordinate display

modes:

✦ Dynamic absolute coordinates (absolute): Absolute

coordinates that change as you move the mouse, as shown

bellow.

: Dynamic absolute coordinates.

✦ Static absolute coordinates (off): Absolute coordinates that

change only when you specify a point, as shown bellow. The

coordinate display is dimmed.

: Static absolute coordinates.

✦ Dynamic polar coordinates (relative): Polar coordinates

that change continuously as you move the mouse, as shown in

Figure 4-17. They appear after you‟ve already specified a point

and are ready to specify a new point, as when you‟re in the

process of drawing a line.

: Dynamic polar coordinates.

You can change the coordinate display in three ways:

✦ Press the F6 key.

✦ Click the coordinates area on the status bar.

✦ Press Ctrl+D.

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Exercise:

Draw the shapes below using line command.

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Lecture (4)

Drawing command Circle


Ameer Mosa Thoeny

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Circle:

The circle command creates one object. Depending on

the option selected, you can provide two or three points to

define a circle. As with all commands, the command line

prompt displays the possible options:

Command: circle

Specify center point for circle or [3p/2p/Ttr]: pick or

coordinates (x,y)

As with most commands, the default and other options are

displayed on the command line. The default option always

appears first. The other options can be invoked by typing

the upper case letter(s) that appear in brackets [].

The options, or methods, for drawing circles are listed

below:

1.Center, Radius:

Specify a center point, then a radius. the radius or

(Diameter) can be specified by entering values or by

indicating a length interactively (pick two points to

specify a length). As always, points can be specified

by picking or entering coordinates.

2. Center, Diameter:

Specify the center point, the diameter

Command:C

Specify center point for circle [3p/2p/Ttr]: 50,50

Specify radius or [Diameter]:D

Specify diameter of circle:20

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3. 2point:

The two points specify the location and diameter. The

tangent OSNAPS can be used when selecting points

with the 2point options.

4. 3points:

The circle passes through all three points specified.

5. Tangent, Tangent, Radius:

Specify two objects for the circle to be tangent to, then

specify the radius. The HR method is extremely

efficient and productive.

Example: Draw this shape using Line, Circle command.

Command: Line

Specify first point:20,20

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Specify next point:23,20




Command:C

Specify center for circle or radius:20,25

Specify radius for circle:0.5

Command:C

Specify center for circle or radius:23,25

Specify radius for circle:0.25

Exercise:

1)Draw this shape using the following setup:

Layers color line type

Box White continuous

Circle yellow dashed

Button Red hidden

Center Green dashed

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2) Create the shape below using the suitable commands.

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Documents

ىلولاا ةلحرملا · 1. SNAP (F9 or status bar) Snap has two modes in AutoCAD: 1- Grid SNAP. 2- Polar SNAP. *Grid snap is a function that forces the cursor to “snap”