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FIRST SEMESTER
COMPUTER AIDED ENGINEERING DRAWING
COMPUTER SIMULATION LAB
DEPARTMENT OF ELECTRICAL ENGINEERING
Prepared By: Checked By: Approved By:
Najeeb Saif Engr. M.Nasim Khan Dr.Noman Jafri
Lecturer Electrical, Senior Lab Engineer Electrical, Dean, FUUAST-Islamabad FUUAST-Islamabad FUUAST-Islamabad
Name: ____________________________________________
Registration No: ____________________________________
Roll No: ___________________________________________
Semester: _________________________________________
Batch: ____________________________________________
EXPERIMENT NO – 01
Introduction to AutoCAD Environment
Starting AutoCAD
Start AutoCAD by clicking on the Windows Start button (bottom left), then move the mouse to Programs then CAD and Modeling then "AutoCAD Architectural Desktop 2" and click on AutoCAD Architectural Desktop 2. A dialog giving various startup options will be displayed. Select the second option: "Start from Scratch" and click OK.
Once you have loaded AutoCAD, move the mouse around until you see a crosshair cursor. The AutoCAD window has a number of important features:
Figure 1 AutoCAD screen.
- The standard Windows drop-down menus.
- The standard Windows toolbar below the menus, it includes: File-New, File-Open, File-Save, Print and "Find and Replace"(!!).
- In addition to the standard toolbar there will be a number of AutoCAD specific toolbars: Object Properties, Draw and Modify (there may be others...?).
- The graphics areas - that's the area where you draw - note the scroll bars and the axis label.
- View Tabs - these 'tabs' give access to different view of the current drawing. The "model" tab should be selected at present.
- The command area - this small window (by default) has space for three lines of text - this is where you type commands.
- The status area, at the bottom of the AutoCAD window, this includes the current cursor position.
NOTE: Despite command line interfaces being considered totally archaic the command area in AutoCAD is absolutely vital! One of the key things I'm trying to "get you to do" in these tutorials is to watch the command area! Using AutoCAD is like a conversation and AutoCAD's half of the conversation comes from the text in the command area...
Command Entry
Typically there are three ways of giving a command:
- Type the command using the keyboard - the command is displayed in the command area.
When I want you to type a command in the command area the AutoCAD command will be written like:
Type: QSAVE
(This means: type the text (qsave) and then press the Enter key or the space-bar)
(Not all commands are on the Menus and/or toolbars)
- Select the command from a menu.
When I want you to select a command from a menu, it will look like:
Select File – Save (This means: click on the 'File' menu and then 'Save' which is one of the items on the 'File' menu).
- Select the command's icon from a toolbar.
When I want you to pick a command from a toolbar, I'll write:
Select Save
(AutoCAD also supports common shortcuts like Ctrl-S for Save)
to update the directory display; if you still can't find your drawing then perhaps you saved the drawing in some other directory - load AutoCAD and then select the File menu, at the bottom of the File menu is a list of recently opened drawings, select your drawing from the list.
Coordinate Systems
When specifying positions you can use Cartesian or Polar Coordinates. Cartesian coordinates are simply a X value, a comma, and a Y value, for example: 100,100. Polar coordinates are a Distance followed by a < symbol and an angle, for example: 10<25. Angles are measured in degrees, with 0 = East and 90 = North. Any of these numbers can have decimal values.
(AutoCAD is a three dimensional CAD system, so you can enter XYZ values instead of the XY values shown here)
The positions specified above are "absolute coordinates" , because they specify a particular position. AutoCAD can also use "relative coordinates" to specify a position relative to the current position, for example: @5.6,-3.4 and @16.32<. (Consider relative coordinates simply as distances)
Draw a "Diamond"
1The "polyline" used below is used to create a sequence of joined line segments, which become one object. Using the "line" command each line segment is a separate object.
(This should draw a "diamond" (a rotated rectangle) shape)
Select Polyline (or type: pline ) and then type: 215,15 absolute Cartesian Coordinate @212<45 relative polar coordinate @212< @212< c
(If you make a mistake, you can undo the last line segment by typing: u ) ( "c" means "close" the shape)
Snap Modes
It is often useful to be able to draw something from (for example) the end of another shape. AutoCAD has a large selection of "snap modes" for this purpose. The most commonly used snap modes are "Endpoint" (which snaps to the end of the selected graphics entity) and "Intersection" (which snaps to the intersection of two graphics entities).
(A simple way to turn Object Snap ON or OFF is to click on "OSNAP" in the status Area. To see the various snap options "right-click" on "OSNAP" (in the status area) and select "Settings")
The object snap modes can either be typed or they can be selected from the standard toolbar or from the snap toolbar:
Figure 2 Object Snap Toolbar
(To display the "Drafting Settings" dialog, click on the "horse-shoe" shaped icon on the end of the Object Snap Toolbar)
Draw an Arc
Select Arc (or type ARC ), then select the midpoint snap mode (or type: MID ) and select the left side of the bottom of the "diamond" polyline you drew before. Then use the midpoint snap to enter points on the right side at the bottom and then the top of the polyline (see figure 2).
Figure 3: Lab1 drawing
C , then type:
30000,24000 the circle centre 6000 the circle radius
(Circle , "C" is the alias for CIRCLE)
Next you will draw another circle, with the same centre, but with a 9500 radius. Press: to "recall"
the last command. Select the centre snap mode (or type: CEN ), then pick the first circle ( NOT the centre of the circle), then type:
9500 the circle radius
(Centre snap , to get AutoCAD to display the Object Snap Modes toolbar, select "Toolbars" from the "View" menu and then select "Object Snap )
Next draw a rectangle from the centre of the circles to 39500,33500. Once you have done that draw another rectangle to the right of the last, start at 39500,24000 and make the rectangle 1500x9500. (Hint: use a relative coordinate @1500,9500)
Now you will draw an arc on the end of the last rectangle (see figure 1). Select Draw - Arc - Start-
Center-End , then select the Endpoint snap mode (or type: END ) and select the bottom-right of the
last rectangle. For the centre point of the Arc, select the Midpoint Snap Mode (or type: MID ) and select the middle of the right edge of the last rectangle. For the end of the Arc, select the Endpoint Snap Mode and select the top-right of the rectangle.
(You might find the following section easier if you turn object snapping ON)
Endpoint Snap Midpoint Snap
Figure 1 showing the location of the ARC
Copy & Rotate...
Now we want to copy & rotate the two rectangles and the arc (3 times), AutoCAD provides the array command to achieve this.
Select Modify - Array , AutoCAD will prompt for the objects to be selected: click below and to the left of the bottom-left corner of the left rectangle and then move the mouse until the selection rectangle encloses the two rectangles and the arc - then click the mouse button (3 objects should be
selected). Then press to end the selection process.
(The array command is used to copy one or more objects in either a rectangular or circular pattern and when a circular pattern is used the objects can be rotated, it can be an incredibly powerful command)
AutoCAD will then prompt for the type of Array - rectangular or polar, type: P for polar. Then use the Centre snap mode to select the centre of the circles. Then type:
the number of items (including the existing item) accept 360 degrees accept "rotate as copied"
(Centre snap After selecting the Centre snap mode, pick the circle NOT the centre)
Figure 2 Drawing with all four "wings" in place
Stretching...
Now you need to stretch the "bottom-left wing" and then remove the inner lines.
Select stretch (or type: S which is the alias for stretch ). Type C and then draw a selection
window around the arc and through the small rectangle (see figure 4), press to terminate the
selection process, click with left mouse button near the selected objects, and type: @-10000, (this is the "stretch distance"). If that worked the building wing should stretch 10 metres (to the left).
Stretch The "C" tells AutoCAD that you want a "crossing" window. The normal selection window
Select only those objects wholly within the section window. A crossing selection window selects objects that are wholly or partly within the selection window.
A useful short-cut to know is that if you draw a selection rectangle left-to-right (in the positive X direction) AutoCAD interprets it as a "window" selection; but if you draw the selection rectangle right- to-left AutoCAD interprets it as a "crossing" selection.
Figure 4 Stretch selection rectangle Explode both the rectangles in the "bottom-left wing" and erase the vertical lines, except the line from the centre of the circles
One Last Circle...
The last object to add is a circle inside the arc of the "bottom-left wing". Select circle (or type: C ).
Select the Center snap mode (or type: CEN ) and click on the arc; then type 3600 (the circle's radius).
Circle Centre snap
More Explosions and Deletions....
The drawing is basically complete; all that needs to be done is to change some of the line-types.
Select: explode from the modify toolbar (or type X ), select all the rectangles at the centre of the
original circles (use a crossing selection window), and then press.
Explode AutoCAD should display a message saying that some objects could not be exploded - ignore the message - it's simply saying that some of the rectangles have already been
There are 8 lines going to the centre (4 are "covered" by the others). You need to erase 4 of them,
select erase from the modify toolbar (or type: E ), then click on each of the four lines and finally
press.
You should now be able to see the lines that were under the lines you erased.
Changing Line Types
Before changing some of the lines to dashed lines, we need to load the Linetype. Select Format - Linetype , then select "Load". AutoCAD will display a list of Linetypes, select "Hidden" (you will need to scroll through the list), then select "OK", then select "OK" again to dismiss the "Select Linetype" dialog box.
Select the 4 lines going to the circle centre and the arcs in the "top- left" and "top-right" wings (see figure 5), then select Modify - Properties , A dialog with the properties of the selected objects is displayed. Change the Linetype to HIDDEN and the Linetype Scale to 75 and dismiss the dialog.
The objects should be redrawn using dashed lines (see figure 5).
EXPERIMENT NO – 03 & 04
Advance 2-D drawing
Objective
The objective of this lab is to produce the diagram below.
During whole this procedure I’ll introduce a number of AutoCAD construction commands: offset mirror and a number of AutoCAD editing commands: fillet, trim, break, and extend In case all that isn't enough for you, you will also learn about layers, hatching , and grip editing.
Layers
Most CAD systems have some kind of overlay concept. AutoCAD uses layers. Layers are used to separate and structure drawings; layers can be turned on and off (for example to vary the amount of detail in a drawing), and can have Linetypes associated with them....
Figure 1: The Layer status area (Object Properties toolbar)
When using AutoCAD, the graphics appears on the current layer, so be careful that the current layer is correct. Look near the top-left of the screen: the current layer and its color is displayed there ( see figure 1 ).
Select the Layers icon or select Format - Layers... , AutoCAD will display the "Layer Properties Manager" dialog. Click on the "New" button and then type CONST (to change the default "layer1" name to something more meaningful), then click on the "Current" button to make this the current layer.
Layers icon (The current layer is the layer to which new graphics is added. The properties command can be used to change a graphics object's layer)
Change the color and then "OK" the dialog box.
Draw "Construction" Lines
Draw a line from the centre: select then line icon (or type L ), and then type:
Line icon
terminate the command
Before continuing, you should "zoom in" to the lines, select zoom-window (or type Z W ), and enclose the lines in the selection rectangle.
Zoom Window
Select offset from the Modify toolbar (or type [the letter 'o'] O ), and then type:
Offset (The offset command makes it easy to set up a series of grid line or (drawing) construction lines)
250 the offset distance select the short horizontal line pick a spot anywhere above the line select the new line pick a spot anywhere above it terminate the command
This should produce one vertical and three horizontal lines.
extend the two lines until they connect to each other.
(The Fillet command is exceptionally useful. It basically extends two lines until they meet, and optionally, inserts a curve where the lines join)
Next, you will trim the sloping line back to the line from the centre.
The trim command is another command that you use very often. The first point you specify selects the "cutting edge", that is, the line to which you are trimming back to. While succeeding selections identify lines to be trimmed.
Figure 4: Points to be selected for the Trim
Select the trim icon from the Modify toolbar (or type TR ), for the "cutting edge" select a spot near
"first point”, press (to end the selection process), select the line to be trimmed ("second point");
and press (to end the command).
Trim icon When picking lines to be trimmed, the part of the line that you select is important. In the example in figure 3, if you pick to the left of the first line selected (rather than to the right of it), then the line will be trimmed from the fillet point to the boundary line. In other words, you'll undo the fillet you just did.
Repeat the fillet and trim process for the other two inner lines.
Creating another Layer
Now you'll create a new layer, select the layers icon (or type LA ), create a new layer and make it the current layer.
To draw the horizontal lines of the pattern, select line (or type L ), and type 0,-6500 @5000,
and press again (to end the command). This line will be trimmed later....
Layers Offset icon
Select offset (or type OFFSET or just o ), type 625 (the offset distance), select the line just
drawn, click below the line to indicate the direction of offset, and press again. Press (to start
another offset), type 1375 (offset distance), select the last line created by the offset, click below the
line to offset down, and press again to end the command.
Offset this line 625 down, If that worked, you should have two pairs of lines. These lines will form the octagonal pattern in the centre. Continue offsetting the "last" line, using the following offsets:
500, 750, 500, 4625, 500
That's most of the horizontal lines in the plan. Next, you will now draw the rest of the pattern.
Firstly, offset the vertical (centre) line 2000 to the right, and then select : trim (or type TR ), pick the
vertical line just created press (end the selection process), type F (this tells AutoCAD that you will draw a fence line - see figure 5), draw a fence line like that shown in the figure (it must cross the
four lines shown), after you pick the second point of the fence line, press twice (firstly to end the fence line and secondly to end the command).
Figure 5: Trimmed line
The following section uses a number of snap modes. The easiest way to work with snaps is to pre-set them and then let AutoCAD dynamically show which snap it can use...
Right-click on "OSNAP" (in the status area at the bottom of AutoCAD's window) and select “Settings” then turn "Endpoint" and "Midpoint" ON (by clicking on them). It would probably be a good idea to turn OFF any of the other snaps that are ON. Finally, make sure the "OSNAP" button is IN.
Select erase from the Modify toolbar (or type E ), select the vertical line used as the "trim guide",
press (end the command).
Now you will draw the line and arc for the pattern, select line (or type L ) then, using the Endpoint snap mode (which should automatically be set by moving the cross-hair near the endpoint), select the right edge of the "bottom" trimmed line and (again using the Endpoint snap mode) select the right
edge of the line above it, then press (end the command).
Select Draw - Arc - Center-Start-End (do NOT pick the arc icon) then, using the Midpoint snap mode
select the middle of the line just drawn, then type @0,-1800 @0,3600. That should have drawn an arc to the right of the vertical line.
