Lectures by pengtt

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									      COMPUTER AIDED
    ENGINEERING DRAWING
                               EE 220 (Electronics)
                           TE 103 (Telecommunication)


•   Pre Requisite : None
•   Credit Hours : 1+ 1
                    COMPUTER
                  FUNDAMENTALS
                               Academic Policies
 Assignment File = A4 Paper File                              File Color

SESSIONAL                             Quantity     Numbers Each    Total
Mid Term                                 1             25           25
Quizzes                                  5             2            10
Assignments / Project / Class            5              -            5
work
Viva / Project                                                       10
Total Sessional                                                      50
Final                                                               50
Subject Total                                                       100
                       Course Outline
Course Description:
• This course is about the drawing basics of two and three dimensional computer
  graphics. Auto CAD replacing conventional methods of drawing, command line
  interface, basic objects and their properties, advanced 2-D and 3-D commands &
  terminologies, Technical Engineering drawings, precisions, different scales of
  measurement, dimensions.

Course Contents
   Week 1:
   – Introduction to Computer Aided Engineering Drawing.
   – Basic info about Conventional drawing methods & techniques and AutoCAD.

    Week 2:
    – Getting familiar with the Auto CAD Environment.
    – Toolbars, working area, sub menus, working modes.
    – Starting with some basic commands.
                    Course Outline
Week 3:
– Engineering drawing basics, line types, shapes.
– Perspective drawing.
– Electronic drawings, basic symbols in electronic circuits.

Week 4:
– Angles of projection.
– Study addressing schemes with different commands.

Week 5:
– Studying basic objects and their commands e.g. circle, donut rectangle, arc,
  ellipse, polygon.

Week 6:
– Studying commands that duplicate objects e.g. array, offset and modify
  commands e.g. trim, break, chamfer, fillet.
                    Course Outline
Week 7:
– Studying Mirror, hatch, ltype, adding toolbars and object snap, zoom, text.
– Making Isometric objects with isometric settings.

Week 8:
– Mid Term Examination (Online Computer Based Exam)

Week 9:
– Applying dimensions (Aligned, Radius, Diameter, Angular, Leaders).
– Increasing / Decreasing working area, changing measuring scales.

Week 10:
– Changing properties of dimensions through style.
– Modifying properties of objects.
– Changing dimensions using stretch and extend.
                    Course Outline
Week 11:
– Studying setting of AutoCAD environment and Layers.
– Raster Images and External Reference Files.

Week 12:
– Changing views for 3d drawings, studying Solids and 3d objects box, sphere,
  cylinder, cone, wedge, torus, extrude, revolve.

Week 13:
– Converting basic shapes example circle, rectangle, polygon, ellipse to solids
  using extrude command.
– Applying revolve command on polyline.

Week 14:
– Subtracting solids and extruded objects. Studying 3d command.
                   Course Outline
Week 15:
– Working with AutoCAD Views, 3D orbit, continuous orbit.
– Generating finished objects by render.

Week 16:
– Basic programming techniques
– Memory addressing techniques in computer programming

Week 17:
– Final Examination (Online Computer Based Exam)
                   Course Outline
Week 15:
– Working with AutoCAD Views, 3D orbit, continuous orbit.
– Generating finished objects by render.

Week 16:
– Basic programming techniques
– Memory addressing techniques in computer programming

Week 17:
– Final Examination (Online Computer Based Exam)
                                   Readings
Course Book.
1. Engineering Graphics with AutoCAD by James D. Bethune

Reference Book.
1. Engineering Drawing by R.K DHAWANEngineering
2. Mastering AutoCAD (2000i *) by George O’ Moura.

*Version according to Latest release Available
                                       Lecture 1
Why a drawing Subject?
•   Drawings have been an essential part of Engineering since the birth of Engineering.
•   Civil Engineering is considered to be the oldest field of engineering.
•   Ancient & pre historic Architecture is flawless & highly Astonishing.
•   Even in those days drawings & simulations were made.
•   There were no computers at that time yet each historic piece is highly accurate.
                                         Lecture 1
Why AutoCAD?
•   It is general purpose drawing tool which means it is used by different professionals
     –    Civil Engineers,
     –    Mechanical Engineers,
     –    Electrical Engineers,
     –    Electronic Engineers,
     –    Computer Engineers.


•    It is easy to use and globally used in Educational Institutions, Universities.

•    It is highly accurate.
                                                      Lecture 2
•      To install AutoCAD 2000i Click on StartRun then type the following path
•      \\fileserver\Softwares\Graphics Section\AuCad 2000i.

AutoCAD Environment
•     Auto CAD 2000i version by AutoDesk USA will be used as a tool for this manual. AutoCAD is a highly developed and user friendly graphics
      design application.
•     AutoCAD files are stored with .dwg extension. Short way to store a file is Ctrl+S.
                                     Lecture 2
Standard Tool Bar / Menu Bar
•    Just like other windows based application AutoCAD also has a Standard Tool bar and a Menu bar for
     opening new files, saving, printing and some other options.




Zoom Bar
•   This bar is used for
    magnifying views. (Please
    note that the object size does
    not change, only the view is
    enlarged)

Drawing Area
•    Black background is working /
     drawing area where the
     drawings are made. In the
     drawing area a plus shaped
     cursor is also visible.
                                    Lecture 2
Cursor
•   This cursor works with the instruction and movements
    of mouse.
•   Depending upon the command it changes shapes.
•   In normal mode its shape is like a plus sign with a
    small square at center and in selection mode
•   it becomes a small square.

Draw / Modify Tool Bars
•   On the Left of the window is a draw tool bar which contains some basic objects like line,
    rectangle, arc, circle, ellipse etc. Next to draw tool bar is a modify tool bar which is used
    for the modification of existing objects e.g. erase, copy, move, rotate, trim etc. All the
    option on draw and modify tool bar will be further discussed in detail.

Command Line Window
•  This window prompts the user to issue commands. When it is in free mode it displays
   “command” written on it which means it is free and asking the user to type any command.
   Once it enters a command it is no more in free mode.

Status Bar
•    This bar reports the status of selected drawing modes e.g. snap, grid, ortho, polar, etc and
     it also reports the location of cursor on screen.
                                                 Lecture 2
 Working Modes
 •   Each action in AutoCAD can be performed in two ways,
 •   using a cursor or mouse
 •    using a command line window by input through key board.
 •   For this course both methods will be studied in detail and also with combination of both.

 Starting with some basic commands / options

 •      Line

                             Cursor                                                      Command Line


                                                                  On command line window type line and press enter 8.
                                                                  In the Specify first point option type 2,4 (where 2 is a co-
                                                                  ordinate on x axis and 4 on y axis). Specify next point give
Using cursor press the line button on the draw tool bar.         some other co-ordinates such as 5,6 or 7,8 etc. To exit line
                                                                  prompt press enter.
Clicking at different locations on the screen will make lines.   e.g.
                                                                  Command : line 8
Press enter to exit line command.                                Specify first point : 2,4 ( x , y )
                                                                  Specify next point or [Undo] : 5,6 8
                                                                  Specify next point or [Undo] : 7,8 8
                                                                  Specify next point or [Undo] : 8
                                               Lecture 2
   •      Erase


                            Cursor                                                       Command Line




Press the erase button on the modify tool bar.                   On command line window type erase. The command line will
                                                                  now read as select objects and the cursor will change to
The cursor will change to selection mode. Select the objects     selection mode. Select the objects by clicking on them one at
by clicking on them one at a time or at any location on the       a time or at any location on the screen click and make a
screen click and make a rectangle, any object that comes          rectangle, any object that comes inside this rectangle will be
inside this rectangle will be selected and its border line will   selected and its border line will become dotted. Press enter to
become dotted.                                                    stop selection mode.
                                                                  e.g.
Press enter to stop selection mode.                              Command : Erase
                                                                  Select Objects : 4 found
Automatically the selected objects are erased.                   Select Objects :       (press enter to exit)
                                                Lecture 2
    •      Copy

                            Cursor                                                       Command Line



                                                                  On command line window type copy. The command line will
Press the copy button on the modify tool bar.
                                                                  now read as select objects and The cursor will change to
The cursor will change to selection mode. Select the objects
                                                                  selection mode. Select the objects by clicking on them one at a
by clicking on them one at a time or at any location on the
                                                                  time or at any location on the screen click and make a
screen click and make a rectangle, any object that comes
                                                                  rectangle, any object that comes inside this rectangle will be
inside this rectangle will be selected and its border line will
                                                                  selected and its border line will become dotted. Press enter to
become dotted.
                                                                  stop selection mode.
                                                                  e.g.
Press enter to stop selection mode.
                                                                  Command: copy
                                                                  Select objects: 1 found
Click any where on the drawing to specify base point (Fixed
                                                                  Select objects:
point with which the object copied).
                                                                  Specify base point or displacement, or [Multiple] : x , y
                                                                   (any location on screen , press M to make multiple copies)
Using cursor click at any location in drawing area. The click
                                                                  Specify second point or displacement, or [Multiple] : x , y
makes a new copy.
                                                                   (any location on screen)
                                                 Lecture 2
    •      Move


                            Cursor                                                       Command Line


                                                                  On command line window type move. The command line will
Press the move button on the modify tool bar.                    now read as select objects and The cursor will change to
                                                                  selection mode. Select the objects by clicking on them one at a
The cursor will change to selection mode. Select the objects     time or at any location on the screen click and make a
by clicking on them one at a time or at any location on the       rectangle, any object that comes inside this rectangle will be
screen click and make a rectangle, any object that comes          selected and its border line will become dotted. Press enter to
inside this rectangle will be selected and its border line will   stop selection mode.
become dotted.                                                    e.g.
                                                                  Command : move8
Press enter to stop selection mode.                              Select objects : 1 found
                                                                  Select objects : 8
Click any where on the drawing to specify base point (Fixed      Specify base point or displacement :x , y 8
point with which the object moves).                               (any location on drawing)
                                                                  Specify second point of displacement
Using cursor click at any location where the object is to be     Or
moved.                                                            <use first point as displacement> : x , y8(any location on
                                                                  screen)
                                                   Lecture 2
    •      Rotate

                            Cursor                                                       Command Line




Press the rotate button on the modify tool bar.
                                                                  On command line window type rotate. The command line will
                                                                  now read as select objects and The cursor will change to
The cursor will change to selection mode. Select the objects
                                                                  selection mode. Select the objects by clicking on them one at a
by clicking on them one at a time or at any location on the
                                                                  time or at any location on the screen click and make a
screen click and make a rectangle, any object that comes
                                                                  rectangle, any object that comes inside this rectangle will be
inside this rectangle will be selected and its border line will
                                                                  selected and its border line will become dotted. Press enter to
become dotted.
                                                                  stop selection mode.
                                                                  e.g.
Press enter to stop selection mode.
                                                                  Command: rotate8
                                                                  Select objects: 1 found
Click any where on the drawing to specify base point (Fixed
                                                                  Select objects: 8
point with which the object rotates).
                                                                  Specify base point: x , y8 (any location on screen)
                                                                  Specify rotation angle or [Reference]: 458 (any number)
Using cursor click where desired rotation is achieved.
                                              Lecture 2
•     SNAP & GRID

                               GRID                                                 SNAP
Grid is a pattern of equally spaced white                   Snap restricts the cursor movement
dots in drawing are.                                        in drawing area to grid dots.



                        Snap                Grid
     X axis              0.5                0.5
     Y axis              0.5                0.5


Snap and Grid options allow achieving accuracy in
drawings. For all the drawings for this course always
remember to turn on snap and grid setting from status
bar (the bar at the bottom of AutoCAD window). By
default the snap and grid spacing on both x and y axis
is 0.5. Gird dots are not visible in the final output /
printout. To change the snap and grid spacing right click
on snap or grid button on status bar and select settings
from drop list. A new window will appear which will
show x and y spacing of both snap and grid to 0.5. It
can be changed to required spacing. Its better to keep
the spacing below 1 and both snap and grid should
have same distance on x and y axis i.e.
                              Lecture 3
The drawing area works according to co-ordinate system with 3 dimensions X-axis,
Y-axis and Z-axis both in negative and positive directions. Origin is always at 0,0
and the angles are as shown in the diagram below. In order to access any location
in drawing area one of four methods discussed below can be used.

Addressing Schemes
AutoCAD supports 4 addressing modes of physics co-ordinate system. These 4
modes can also be defined as 4 different ways to reach any location on screen.
Addressing modes help drawing conveniently i.e. effort and number of cursor clicks
is reduced, logical drawings can be made easily and lengthy calculations are
avoidable. In the previous lab one of these 4 addressing modes was discussed
which is also widely used in real world that is Absolute Rectangular Co-ordinate
system.

                                                  Absolute           Relative

                             Rectangular            x,y              @x,y
                                Polar             u < angle         @ u< angle
                                            Lecture 3
Absolute Rectangular                                           Relative Rectangular
With this scheme screen can accessed using normal co-          This scheme is similar to Absolute Rectangular system except
ordinate system which implies x,y where x will be any number   it has an additional @ sign which means that the origin is
on x-axis and y a number on y-axis.                            temporarily shifted from its actual position to the last point
e.g.                                                           selected by the user.
Command : line                                                 e.g.
Specify first point : 2,4 ( x , y )                            Command : line
Specify next point or [Undo] : 5,6                             Specify first point : @2,4 ( x , y )
Specify next point or [Undo] : 7,8                             Specify next point or [Undo] : @5,6
Specify next point or [Undo] :                                 Specify next point or [Undo] : @7,8
                                                               Specify next point or [Undo] :



Absolute Polar                                                 Relative polar
This method has a metric distance followed by a less than      This scheme is similar to Absolute Polar system except it has
sign and an angle.                                             an additional @ sign which means that the origin is
e.g.                                                           temporarily shifted from its actual position to the last point
Command : line                                                 selected by the user.
Specify first point : 2,4 ( x , y )                            e.g.
Specify next point or [Undo] : 5<90                            Command : line
Specify next point or [Undo] : 4<45                            Specify first point : 2,4 ( x , y )
Specify next point or [Undo] :                                 Specify next point or [Undo] : @5<90
                                                               Specify next point or [Undo] : @4<45
                                                               Specify next point or [Undo] :




Of these four addressing schemes Absolute Polar system will be excluded from the course.
                                 Lecture 3
Example
The following figure has been drawn with combination of Absolute Rectangular and Relative
Polar system.         .

                                             Command: line
                                             Specify first point: 0,0
                                             Specify next point or [Undo]: 0,4
                                             Specify next point or [Undo]: 2,4
                                             Specify next point or [Undo]: 2,2
                                             Specify next point or [Undo]: 4,2
                                             Specify next point or [Undo]: 4,0
                                             Specify next point or [Undo]: 0,0
                                             Command: line
                                             Specify first point: 0,4
                                             Specify next point or [Undo]: @2<45
                                             Specify next point or [Undo]: @4<0
                                             Specify next point or [Undo]: @1<225
                                             Specify next point or [Undo]: @2<270
                                             Specify next point or [Undo]: @2<180
                                             Specify next point or [Undo]: @2<90
                                             Specify next point or [Undo]: @2<0
                                             Command: line
                                             Specify first point: 2,4
                                             Specify next point or [Undo]: @1<45
                                             Command: line
                                             Specify first point: 2,2
                                             Specify next point or [Undo]: @1<45
                                             Command: line
                                             Specify first point: 4,2
                                             Specify next point or [Undo]: @1<45
                                             Command: line
                                             Specify first point: 4,0
                                             Specify next point or [Undo]: @2<45
                                             Specify next point or [Undo]: @4<90
                             Lecture 3
Exercise
Draw the following diagram using combination of Absolute Rectangular and Relative
Polar system.      .
                                         Lecture 4
All object commands in AutoCAD are syntaxed after their names e.g. command syntax for circle is circle,
rectangle is rectangle etc. Almost All commands in AutoCAD have more than one option in them. Once a
command is issued it will show its different options at different levels. Each option may be selected by typing
                          .
its name. Remember that values can be assigned in both ways i.e. through keyboard or by a click of a
mouse.

Circle
The circle command shows 5 options or five different ways of making a circle. It will be read as center point,
3P, 2P, Ttr. Default method is the center point.
Command: circle
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]:
center point : In this method any point is defined followed by another point. An invisible line is created upon
these points which will be the radius of circle.
3P: This option means any 3 points defined by user upon which a circumference is created.
2P: Any two points upon which an invisible line will be created which will be the diameter of the circle.
Ttr: Two tangent lines should be previously available. These lines will be defined as tangents to the circle.


Donut
This command draws a donut and requires two diameters,
one for inner circle and other for outer.
Command: donut
Specify inside diameter of donut <0.5000>: 2
Specify outside diameter of donut <1.0000>: 3
Specify center of donut or <exit>:
                                          Lecture 4
Rectangle
Command: Rectangle
Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]:
  first corner point: In this method any point is defined followed by another point. An invisible line is created
                          upon these points which will be the diagonal of this rectangle.
Chamfer: Replaces 1 sharp edge of rectangle with 2 sharp edges.
Elevation: elevates the rectangle to a height on z-axis.
Fillet: Replaces 1 sharp edge of rectangle with a smooth edge.
Thickness: Changes the thickness of rectangle.
Width: Changes the width of rectangle.



          Rectangle                                 Chamfer                                    Fillet



Arc                                                                                 Center
Command: arc
Specify start point of arc or [Center]:                       Start                                      En
                                                                                                         d
Specify second point of arc or [Center/End]:
Specify end point of arc:
The order of drawing arc is not fixed. End point can also be defined
before center point.
                                       Lecture 4
Ellipse
Command: Ellipse
Specify axis endpoint of ellipse or [Arc/Center]:
Specify other endpoint of axis:
Specify distance to other axis or [Rotation]:
                                                            Axis end pnt                 Other endpoint
                                                                           Distance to
                                                                           other axis




Polygon
This command is used for drawing objects having
minimum 3 sides andmaximum of 1024 sides.

Command: polygon
Enter number of sides <4>: 5
Specify center of polygon or [Edge]:
Enter an option [Inscribed in circle/Circumscribed about circle]
<I>:
Specify radius of circle:
                                            Lecture 4
Polyline
Polyline is a line with a non zero width.

Command: pline
Specify start point:
Specify next point or [Arc/Halfwidth/Length/Undo/Width:
Arc: An arc of polyline will be made
Halfwidth:
Length:
Undo:
Width:
                                                       Starting
                                                        width
                                                                  Ending
                                                                   width




                                                                           Width

                                               Half
                                               width
                                          Lecture 4
Multiline
A multi line creates two lines parallel to each other. Scale is the distance between two lines.
Justification is the edge of end points.
Command: mline
Specify start point or [Justification/Scale/STyle]: scale
Enter mline scale <0.25>:
Specify start point or [Justification/Scale/STyle]: justification
Enter justification type [Top/Zero/Bottom] <top>:
Lecture 4
                                      Lecture 4
Exercise
Convert the following drawing to equivalent Axonometric and Oblique drawings.
                                              Lecture 5
Copy, Offset and array commands are used for making one or more duplicates/copies of any object. Where
as trim, break, chamfer and fillet are modification commands.



Offset
This command creates a copy of object at some specified distance and side such that all sides are
parallel to the new copy

Command: offset
Specify offset distance or [Through] <1.0000>: 1.5
Select object to offset or <exit>: Select objects using cursor
Specify point on side to offset: Click on any one side of the object to be offset
                                        Lecture 5

Array
This command is used to make multiple copies at one time. It has two working methods Rectangular and
Polar.
Command: array
After typing array command press enter.
Array window will appear.
Click on select objects button, the window will disappear and on the drawing area select the objects to be
arrayed.
After selecting objects press enter to return to array window.
After supplying suitable values in respective Rectangular or Polar arrays click on the preview button.
If the preview is ok press accept or press modify to make changes.
                                     Lecture 5
                   Rectangular                                                 Polar


                                                     This method copies objects on circle concept. Like a
This method has number of rows, number of columns,
                                                     circle polar array has a center, in addition to it the
distance between rows and distance between
                                                     total number of objects on the circular path and angle
columns. Rows multiply by columns gives the total
                                                     to be filled. For 360 degrees the entire circular path is
number of copies than can be made.
                                                     covered. Items can also be rotated along with angle.
                                      Lecture 5

Trim
This command is illustrated on two overlapping lines.
Select the objects as shown in the diagram.
Command: Trim
Select object:
Select object to trim:




                                                        Result
                                      Lecture 5
                                                                        Specify first
                                                                        break point



                                                       Specify second
                                                       break point
Break
This command works on one object
and is illustrated on a circle.
Select the objects as shown in the diagram.
Command: Break
Select object:
Specify second break point or [First point]: first
Specify first break point:
Specify second break point:


                                                     Result
                                       Lecture 5
Chamfer
Chamfer converts one sharp edge into two edges. It has two methods, distance and angle.
Command: Chamfer
Select first line or [Polyline/Distance/Angle/Trim/Method]:
Select second line:

             Object                      Chamfer with trim                 Chamfer with no trim




            Chamfer by distance method                        Chamfer by angle method

                         Second
                         distance                                          Angle
                                                                First
                                                                distance
              First
              distance
                                       Lecture 5
Fillet
Fillet converts one sharp edge into one smooth edge.
Command: Fillet
Select first object or [Polyline/Radius/Trim]: Radius
Specify fillet radius <0.5000>: 1
Select first object or [Polyline/Radius/Trim]: Radius
Select second object:



                Object                    Fillet with trim   Fillet with no trim
                                        Lecture 5
First Angle Projection
Front, Right and top view of any object are known as frist angle projection.
                                           Lecture 6
Mirror command makes a mirror copy of an object. Hatch is an object command which fills a closed boundary
with some pattern. Ltype is used to modify the type of line.
During drawings some special areas or points may be required to approach but may be out of range or may
not accurately be accessible e.g. intersection of two lines, midpoint or end points of line, center of a circle etc.
All these points can be accessed by activating object snap tool bar. Zoom command or zoom tool bar is used
for zooming views.



     Mirror
     This command makes a mirror copy or a copy with inverted sides of object at some specified
     distance.
     Command: Mirror                                                Original        Mirror Object
     Select objects: Specify opposite corner: 3 found               Object             Object

     Select objects:
     Specify first point of mirror line: Specify second point of mirror line:
     Delete source objects? [Yes/No] <N>:
                                                        Lecture 6
Bhatch
This command is used a closed boundary (e.g. rectangle, circle, polygon) with a pattern.
Command: Bhatch




1)Click Swatch to change the hatch design / pattern.
                                                                   1)On the hatch window click Advanced and check other options.
2)Click Pick Point to pick a closed boundary.
                                                                   2)Click Remove Islands and pick a closed boundary and check its
3)Click Preview to check the preview before applying.              Impact.

4)During preview the Hatch window disappears. Make a right click
  or press enter to return to hatch window
                                          Lecture 6
Ltype
This command is used to change the style of a line. Once
    a line type is made current it is applicable to all
    objects that will be drawn including circle, rectangle,
    arc, ellipse, polygon, etc.
Command: Ltype
      Click Load to and choose a line type design /
           pattern.

     Select and highlight the line type recently added
         and want to appear on the objects and make it
         current by clicking Current button. Line type
         will not be applicable until it is set to current.

     If the details are not visible select Show Details
          button.
     Change the Global Scale Factor and Current
          Object Scale to adjust the line type scale in
          case if line type is not properly visible.
                                        Lecture 6
Adding Tool Bars
To add toolbars, on the standard toolbar click View and select Toolbars and from the toolbar window activate
Object Snap.
                                                   Lecture 6
Object Snap
This option helps select some special points that may not be accurately accessible but may be required to
access e.g. intersection of two lines, midpoint or end points of line, center of a circle etc. Press F3 to activate
object snap option or on the standard toolbar click View, select Toolbars and from the toolbar window
activate Object Snap.


      _________________Temporary Tracking point
      _________________Snap From

      _________________Snap to end points (e.g. end points of a line)
      _________________Snap to mid point (e.g. mid point of a line)

      _________________Snap to intersection (e.g. intersection of any two lines)
      _________________Snap to apparent intersection (lines that currently don‟t intersect but will intersect if extended in their paths)
      _________________Snap to extension

      _________________Snap to center of a arc, circle or ellipse
      _________________Snap to either of the four quadrants of a circle
      _________________Snap (a line) to tangent (it becomes a tangent) to a circle

      _________________Snap a line perpendicular to another line
      _________________Snap a line parallel to another line


      _________________Snap to a node

      _________________Snap a point nearest to object
      _________________Snap to none

      _________________Open Object Snap Settings Window
                                        Lecture 6
Zoom
This command changes the view.
Command: Zoom
[All/Center/Dynamic/Extents/Previous/Scale/Window] <real time>:
real time: Zooms the views with the upward and downward movement of mouse. Upward movement = zoom
in and downward movement = zoom out.
All: Zooms such that the drawing (even if not on working area) and the working area (dotted region) both are
visible.
Center: Zooms by prompting the user to define any point on working area which will be the center of working
area in the new view.
Dynamic: Zooms using a resizable and movable window.
Extents: Zooms such that drawing is perfectly covered with all its extents visible.
Previous: Shows the previous zoom view.
Scale: Zooms by defining a scale.
Window: Zooms by prompting the user to define an area using a rectangular window. The area defined
becomes the new view.
                                    Lecture 6
Text
This command is used to write a multi line text.
Command: Mtext. (make a rectangle on screen after issuing the command)
After defining the text area the texst window will appear.
      Select Properties tab window.
      Change the width to No Wrap.
                                     Lecture 7
Settings For Isometric
Another approach to make isometric drawing while reducing steps is to change the setting.
Right Click on SNAP or GRID button on status tool bar (at the bottom of AutoCAD window) and select
    settings.
On the Drafting Settings window under the tab of Snap and Grid change Snap type & style to Isometric
    and press ok.
The grid dots of drawing area on screen have changed to 30 degree projection.
                                            Lecture 7
Drawing Isometric Objects
Activate ORTHO from the status tool bar (at the bottom of
AutoCAD window). After the activation of ORTHO the cursor
restricts drawing to only two directions vertical and horizontal
axis. SNAP, GRID
and ORTHO visibly active in the snap shot on left.

1)Issue the line command and specify any starting point.

2)Just position the cursor in the direction where the line is to be
drawn (as shown in fig on left).

3)On the command prompt type the length (e.g. 5). Press enter.

Isometric objects have 3 visible sides (left, right and top) hence
Isometric Settings work one by one for these three sides.
Default side of Isometric setting is left. Once a side (e.g. left) of
the object has been made press F5 key to change the side.
                                       Lecture 7
The command prompt will show <Isoplane Right> (as shown in diagram below) and the cursor will project to
right side axis. Draw the other side with the same procedure.
                                       Lecture 8
Dimensions describe the measurement of length, height, width, angle etc of any object.

Dimensions
Dimension option is visible on the standard toolbar.
Make some objects to apply dimensions (e.g. lines, circles, as shown below).
Under the option of dimension select aligned.
Click one by one on the two endpoints of any available line.
Similarly check all other options i.e. Radius, Diameter, Angular and Leader.
                                       Lecture 8
Increasing or Decreasing Working Area
Working area needs to be changed according to drawing and their dimensions. Limits command is used to
change the dimension.

Limits
Command: limits
Specify lower left corner or [ON/OFF] <0.0000,0.0000>: (It’s a good approach to keep this limit unchanged)
Specify upper right corner <12.0000,9.0000>: 20,20



Changing Measuring Scales
AutoCAD supports 5 types of measuring scales. Type units. Units
window will appear. Following are five types of scales
•Architectural
•Decimal           (Default)
•Engineering
•Fractional
•Scientific
Civil engineering maps and house plans are made on Architectural
Scale.
                                        Lecture 9
All objects previously created on drawing area may need changing or editing.


Editing Dimensions
Dimensions may sometimes not look appropriate to size of objects. Hence they can be modified.


On the menu bar click on dimension and select style.

A new window Dimension Style Manager will open.

On this window click Modify.
                                        Lecture 9
Another new window of Modify Dimensions Style opens.
The current tab option active on this window is the first
available Lines and Arrows.

On this tab under the Arrowheads area change the
arrow size according to requirements.




                                                     On the second tab i.e. Text change the text height
                                                     according to requirements.

                                                     Also check other settings which may look appropriate.
                                         Lecture 9
Editing Objects
Objects previously created may later need some modifications. Properties of objects can be modified by
first selecting the objects and then clicking on the properties button. If a single object was selected before
clicking the properties button then all the properties applicable to it will be visible. If multiple objects of
different types are selected then only the common properties applicable to all the select objects will be
visible.



                                                                Properties Button
                                            Lecture 10
AutoCAD Working environment Settings
Auto CAD environment‟s default settings can be
changed according to user‟s needs.
Example the background colour, cursor colour, etc.

Any where on the black drawing area right click and select options.




                                                     A new window Options will open. On this window click the second tab
                                                     Display.

                                                     From the Display tab option select colors. Again a new window of
                                                     colour option appears.
                               Lecture 10
Select what ever is appropriate or select Default All for default settings.
                                       Lecture 10
Layers
Layers in drawing tools are a very powerful and helpful aid in the way they work as real world plastic
transparencies. Hence a drawing on one layer may only be visible on the other to help draw some other object
without modifying the previous one.

Default layer is layer Zero or „0‟. Its always there and has been through all the labs previously worked out in
this lab manual. It‟s a good approach to leave this layer unmodified.
To create a new layer, click on the Layers button, the second button from left on the Layer tool bar as marked
below.




                                                 A layer will only work if it is set to current is in unlock mode
                                                 and it is turned on.
                                         Lecture 10
                            Layer Name




                                           An Illustration of Laywe Tool Bar
                         Layer Colour


                        Lock or Unlock
                               A Layer


         Turn a Layer
          On or Off




Raster Images
Raster Images are the external image files which can be
inserted in Autocad and are helpful in drawing and tracing.
                            Lecture 10
Picture on right shows an example of a raster image.
                                       Lecture 10
External Reference Files
External Reference files are one with drawings inserted as a reference from an other or say a parent file.
Once any changes are made in the drawings of parent file, automatically the drawing in all the files in which
this drawing has been externally referred will show this change.
                                      Lecture 10
This diagram shows a parent file and some nascent files which contain the drawings which are externally
referenced from the parent file.
                                      Lecture 10
This diagram shows the changes in parent file and their impact on
the referred files.
                                      Lecture 11
In order to view the 3d objects properly view settings should be changed.

From the View option on standard tool bar activate the Shade toolbar.




 Or from the Standard tool bar simply click on View then select Shade and
 then Flat Shaded
                                       Lecture 11
Activate the Solid toolbar. There are five solid objects visible on this tool bar. Click on any one and supply
the proper values at different command prompt options for respective objects.
                                       Lecture 12
Extrude
All the basic commands studied in experiment 3 e.g. circle, rectangle, polygon, ellipse were just 2 dimensional
objects but they can be converted to 3 dimensional from there 2-D statistics using extrude command.

Before using extrude command activate Shade & View toolbars.

From the Shade tool bar click on Flat Shade and from the View tool bar click

Make any object circle, rectangle, polygon or an ellipse. Type extrude and select that object.




Extrude
This command converts 2-D objects to 3-D objects.
Command: Extrude
Select objects: Select objects to extrude using cursor
Specify height of extrusion or [Path]: Enter any suitable number
Specify angle of taper for extrusion <0>:
                            Lecture 12
This picture shows a circle and its extruded form
                                      Lecture 13
Subtract command subtracts a portion of two overlapping 3D objects.

Subtract
Draw any two 3D solid or extruded objects and place them in such a way that they overlap each other.
(As shown in the diagram below)




Subtract
This command converts 2-D objects to 3-D objects.
Command: Subtract
Select solids and regions to subtract from .. (Select the cube)
Select solids and regions to subtract .. (Select the sphere)
                       Lecture 14

2 overlapping objects before subtraction




                                           Object after subtraction
           Lecture 15
Projects
           Lecture 15
Projects
           Lecture 16
Projects

								
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