Engineering 22
©
AutoCAD
2D Construction-1
Bruce Mayer, PE
Licensed Electrical & Mechanical Engineer
BMayer@ChabotCollege.edu
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Learning Goals
 Become Proficient with invocation of
AutoCAD Drawing Commands
 Create Basic AutoCAD 2-Dimensional
Drawing Elements
• e.g.; Lines, Circles, Ellipses and PolyGons
 Use a Combination of ACAD 2D
Elements to construct more Complex
2D Shapes
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Initiating AutoCAD Commands

Generally There are
Three Ways to
Invoke AutoCAD
commands

Example – Draw a
Circle
1. By PullDown Menu
If you get
“Stuck” in ACAD
Try the
ESCAPE Key
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Invoke Commands cont
2. By Typing the
Command into the
Command line

The Typed
Commands often
have ShortCuts

Instead of typing
circle, type only c
Engineering 22 – Engineering Design Graphics
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3. Using a Tool from a
ToolBAR
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Drawing Lines
 To Random Points
• Type in line (or l),
or click the
Line Tool
• Pick Points
Using the Mouse –
The Line follows the
mouse.
• Click at each vertex
• Terminate Line by
Hitting Enter or Esc
Engineering 22 – Engineering Design Graphics
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 Many times these
“Assisters” Help with
Line Drawing
• SNAP
• GRID
• ORTHO
• OSNAP
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Random Pts Line
Mouse Click
Sets Vertex
• This Example uses SNAP and GRID, but NOT Ortho
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Closed Line

To Make a
CLOSED figure of
an arbitrary shape
1. Invoke line and set
at least 3 Vertices
2. With Line still
ACTIVE type in the
command-line one
of:
Line Ready to Close
Closed Line
– close
– c
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Erasing
 To delete drawing
elements use the
Erase command
 Invoke Erase by
• PullDown Menu
• Click the Erase Icon
on the Modify
ToolBar
• Type in Command
line erase or e
 To Erase:
Engineering 22 – Engineering Design Graphics
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• Start Erase
• Select Element(s)
with Mouse
• Hit Enter or RIGHT
Click
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Line by Coords
 Type in the
Command Line the
CoOrds, one at a
time
 Make a Box
 Be Sure That
“Dynamic Input” is
Turned OFF
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Line by Relative CoOrd
 To Draw a Line
RELATIVE to a
Given point
• @ x, y
 Invoke the line
command
• @ dist, <angle
 ID a Starting point
with the Mouse or
by CoOrds
– x & y are CoOrds
RELATIVE to the
Current Point
– The distance and
angle (in Degrees,
thakfully) Relative to
Current Point
 In the command
Line Type Either
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Relative Lines
 By X & Y
Engineering 22 – Engineering Design Graphics
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 By Distance & 
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Construction Lines
 Construction Lines
are Very Useful for
“Blocking In” or
“Aligning” Drawing
Objects
 They are lines of
Infinite (h) Length
that may be trimmed
later
Engineering 22 – Engineering Design Graphics
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 Invoke Construction
Line by
• Construction Line
Tool on Drawing Tool
Bar
• Command line →
xline or xl
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Some Construction Lines
Construction Line
Options
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Construction Line Offset
 Lets
• Make a Layer; Green
in Color
• Draw some Lines
• Offset a Construction
Line
Hit ENTER twice to
ReInvoke ConstrLn
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Drawing Circles
 To Draw a circle
Invoke the
Command
• Click the Circle Tool
• Use the PullDown
Menu: Draw →
Circle → option
• Type in the
Command Line one
of
– Circle or c
 Command Line Text
Command: circle
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 2p
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Drawing Circles cont

To Draw a Simple
Circle
1. Click the Circle Tool
2. Use the Mouse to
Pick a Center Point
 Circle by
• Pick Center Point
• Drag Radius
3. Do one of
– DRAG with the
mouse to Set the
Radius
– Type in a Number for
the radius
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Drawing Circles cont

The Circle
Command has
Many useful
options
Engineering 22 – Engineering Design Graphics
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 Default → Center,
Radius
 Center, Diameter
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Drawing Circles cont

2 Points
 Tan, Tan, Tan
Start
Pt

Tan, Tan Radius
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Circle Center Marks/Lines

Technical Drawing
Practice Calls for
Marks and Lines to
ID Circle Centers
Center Mark
Only
Center Mark &
CenterLines
Engineering 22 – Engineering Design Graphics
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 CenterMark Sizing
 ACAD has many
Commands and
Parameters that Can
ONLY be accessed
thru the Command Line
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
SETVAR command
 Typing SetVar in the
Command Gives
access to 480
AutoCAD System
Variables
 For Example, The
acad.dwt has a
Center mark Size of
0.09”
 Use Variable
DIMCEN to Change
to 5X this Value
Partial Listing by
Setvar → ? → *
Note: Can type DIMCEN w/o SetVar
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
CenterLines by Dim Style
 The acad.dwt
default for Circle
Center is a MARK
only; NO Lines
 To Change, use
Dimension Styles
 Invoke the Dim Style
Dialog by one of
Engineering 22 – Engineering Design Graphics
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• Dim Style Tool on the
Dimension ToolBar
• PullDown Menus:
Dimension →
Dimension Style...
• Command Line →
DIMSTYLE
 Any of these actions
Activates the Dim
Style Dialog Box
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
CenterLines by Dim Style cont
 The DimStyle Dialog
Box
 Select Modify... To
activate next dialog
Engineering 22 – Engineering Design Graphics
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• Select the Symbols
and Arrows Tab
Can Use Instead
of DIMCEN
Check this Button to
Produce CntrLns
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
CenterLines by Dim Style cont
 After the change
Engineering 22 – Engineering Design Graphics
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 A new Circle
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
POLYLINE Command
 The PLINE
command allows
you to create
"grouped" objects
that can be
extruded, given line
width on the
screen, and can
contain arc
segments.
Engineering 22 – Engineering Design Graphics
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 To Invoke the
PolyLine Command
• PullDown Menu:
Draw → Polyline
• The Tool on the
Drawing ToolBar
• Command Line:
pline or pl
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Polyline Construction
 PolyLines Are Constructed using the
same methods as “Regular” Lines, but
the WIDTH of the Line is VARIABLE
 PLINE also has a List of OPTIONS
[Arc/Halfwidth/Length/Undo/Width]
• Width and
Halfwidth Set
the Starting &
Ending PolyLine
width(s)
Engineering 22 – Engineering Design Graphics
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• Arc Helps Fine
Tune PLine Arcs
• Length allows
typing of the Next
Segment Length
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Some PolyLines
Command: pline
Specify start point:
Current line-width is 0.2000
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: h
Specify starting half-width <0.1000>: .05
Specify ending half-width <0.0500>:
Specify next point or [Arc/Halfwidth/Length/Undo/Width]:
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]:
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]:
Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: *Cancel*
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Some PolyLines cont
PLINE
Specify
Current
Specify
Specify
Specify
Specify
Specify
start point:
line-width is 0.1000
next point or [Arc/Halfwidth/Length/Undo/Width]: w
starting width <0.1000>: 0
ending width <0.0000>: 1.2
next point or [Arc/Halfwidth/Length/Undo/Width]:
next point or [Arc/Close/Halfwidth/Length/Undo/Width]: *Cancel*
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Some PolyLines cont
Command: pl
PLINE
Specify start point:
Current line-width is 1.2000
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: h
Specify starting half-width <0.6000>: .05
Specify ending half-width <0.0500>:
Specify next point or [Arc/Halfwidth/Length/Undo/Width]: a
Specify endpoint of arc or
[Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width]:
*Cancel*
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
SPLINE command
 A spline is a smooth
curve that is fitted
along a number of
control points
 The ACAD Spline
command creates a
type of spline known
as a NonUniform
Rational B-Spline,
NURBS for short
Engineering 22 – Engineering Design Graphics
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 To Invoke the Spline
Command
• PullDown Menu:
Draw → Spline
• The Spline Tool on
the Drawing ToolBar
• Command Line:
spline or spl
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
SPLINE Construction
 Splines Are Constructed using the same
methods as “Regular” Lines, but the
segments are splined arcs
• Constructing a Spline
Command:
spline
Specify first point or [Object]:
Specify next point:
Specify next point or [Close/Fit
<start tangent>:
Specify next point or [Close/Fit
<start tangent>:
Specify next point or [Close/Fit
<start tangent>:
Specify next point or [Close/Fit
<start tangent>:
Specify start tangent:
Engineering 22 – Engineering Design Graphics
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tolerance]
tolerance]
tolerance]
tolerance]
*Cancel*
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
ELLIPSE command
 The Ellipse
 To Invoke the Ellipse
command includes a
Command
number of different
• PullDown Menu:
Draw → Ellipse
creation options.
• The default option is
to pick the two end
points of an axis and
then a third point to
define the
eccentricity of the
ellipse.
Engineering 22 – Engineering Design Graphics
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• The Ellipse Tool on
the Drawing ToolBar
• Command Line:
eLLipsE or EL
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
ELLIPSE Construction
Command: el
ELLIPSE
Specify axis endpoint of
ellipse or [Arc/Center]:
Specify other endpoint of
axis:
Specify distance to other
axis or [Rotation]: *Cancel*
ELLIPSE
Specify axis endpoint of
ellipse or [Arc/Center]: a
Specify axis endpoint of
elliptical arc or [Center]:
Specify other endpoint of
axis:
Specify distance to other axis
or [Rotation]:
Specify start angle or
[Parameter]:
Specify end angle or
[Parameter/Included angle]:
Engineering 22 – Engineering Design Graphics
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ELLIPSE
Specify axis endpoint of
ellipse or [Arc/Center]: c
Specify center of ellipse:
Specify endpoint of axis:
Specify distance to other axis
or [Rotation]: <Ortho on>
<Ortho off>
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
PolyLines & Ellipses
 Let’s Draw some of the Elements that
have many Options
• PolyLines
• Ellipses
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
All Done for Today
Not a CAD
Circle But a
Boat Circle
Engineering 22 – Engineering Design Graphics
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Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt
Engr/Math/Physics 25
Appendix
f x   2 x  7 x 
9x  6
3
2
Bruce Mayer, PE
Licensed Electrical & Mechanical Engineer
BMayer@ChabotCollege.edu
Engineering 22 – Engineering Design Graphics
35
Bruce Mayer, PE
BMayer@ChabotCollege.edu • ENGR-22_Lec-0_2D_Construction-1.ppt