1. Sacramento City College Engineering Design Technology
Drawing Basic Shapes
Sacramento City College
Engineering Design Technology
Drawing Commands

2. Objectives The CIRCLE command Use the @ symbol function
The CIRCLERAD system variable
Use symbol function
The LASTPOINT system variable
The ARC command
The POLYGON command
The ELLIPSE command
The RECTANGLE command
The DONUT command.
Drawing Commands

3. Drawing Commands

4. Drawing Circles
Drawing Commands

5. Drawing Circles The CIRCLE command:
Enter C or CIRCLE at the Command: prompt OR
Pick the Circle button in the Draw toolbar
Select Circle from the Draw pull-down menu
Drawing Commands

6. Drawing Circles A circle can be drawn by: 1. Radius. 2. Diameter.
3. Two point.
4. Three point.
5. Tangent to two objects.
6. Tangent to three objects.
Drawing Commands

7. Drawing Circles By Radius
The radius
is the distance from the center to the circumference of a circle or arc.
The circumference is the perimeter or distance around the circle
Circumference
Radius
Drawing Commands

8. Drawing Circles By Radius
Method #1 – By Radius
To draw a circle by specifying radius:
Pick center point.
Specify radius with mouse.
The radius value chosen becomes the default setting for the next time you use the CIRCLE command.
Drawing Commands

9. The CIRCLERAD System Variable
Drawing Commands

10. The CIRCLERAD System Variable
Use the CIRCLERAD variable to set a radius default.
You can then draw circles of the exact same size.
Circle, pick center, [Enter]
CIRCLERAD variable is automatically reset every time you draw a circle.
Drawing Commands

11. The CIRCLERAD System Variable
When the CIRCLERAD variable is set:
Pick the circle center point.
Press [Enter].
Circle is drawn with radius = CIRCLERAD
Size of circle comes from value of CIRCLERAD
Set CIRCLERAD to 0 if you don’t want a default value for a circle OR
Pick new radius with mouse.
Drawing Commands

12. Drawing Commands

13. Drawing Circles
Drawing Commands

14. Drawing Circles By Diameter
Method #2 – By Diameter
A circle can also be drawn by specifying the diameter.
Command: C or CIRCLE
3P/2P/TTR/<Center point>: (pick the center point)
Diameter/<Radius>: D
Diameter: (Drag the circle to the desired diameter)
Command:
Drawing Commands

15. Drawing Circles By Diameter
Watch the screen carefully.
The pointer measures the diameter but the circle passes midway between the center and the cursor.
See Fig. 5-4.
Drawing Commands

16. Drawing Commands

17. Drawing Circles By Diameter
If you use the Diameter option,
the previous default radius setting is converted to a diameter.
If you use the Radius option,
the previous Diameter option is converted to a radius.
Drawing Commands

18. Drawing a Two Point Circle
Drawing Commands

19. Drawing A Two Point Circle
Method #3 – By Two Points
A circle can be drawn by specifying two points.
Pick two points on opposite sides of the circle.
Use when diameter is known, but the center is difficult to find.
Drawing Commands

20. Drawing Commands

21. Drawing A Three Point Circle
Drawing Commands

22. Drawing A Three Point Circle
Method #4 – By Three Points on Circle
A circle can be drawn by picking three points on the circumference of the circle.
Use when three points on the circumference of the circle are known.
AutoCAD calculates the radius from the three points picked.
Drawing Commands

23. Point #3 – not yet selected
Drawing Commands

24. Drawing a Circle Tangent to Two Objects
Drawing Commands

25. Circle Tangent To Two Objects
Method #5 – Tangent to 2 Objects at a given radius (TTR)
The term tangent refers to a line, circle or arc that comes into contact with an arc or circle at only one point.
That point is the point of tangency.
A line drawn from the circle’s center to the point of tangency is perpendicular to the tangent line.
Drawing Commands

26. Circle Tangent To Two Objects
Point of Tangency
Is an extremely important geometric relationship.
Is used in engineering/architecture
Examples
Constructing an exit ramp on freeway.
Determining the start/end point of a curve on an object.
Drawing Commands

27. Point of Tangency Point of Tangency Line forms a Right Angle at
the Point of
Tangency
Drawing Commands

28. Circle Tangent To Two Objects
Drawing Commands

29. Circle Tangent To Two Objects
Method #5 – Tangent to 2 Objects at a given radius (TTR)
The Tan, Tan, Radius (TTR ) option is used to
Draw a circle tangent to two objects and
To a specific radius.
Drawing Commands

30. Circle Tangent To Two Objects
Command: C or CIRCLE
3P/2P/TTR/<Center point>: TTR
Enter Tangent spec: (pick first item)
Enter second Tangent spec: (pick second item)
Radius <current>: (type a radius value, press [Enter])
Command:
Drawing Commands

31. Circle Tangent To Two Objects
If the radius entered is too small, AutoCAD gives you the message:
“Circle does not exist.”
Drawing Commands

32. Drawing a Circle Tangent to Three Objects
Drawing Commands

33. Circle Tangent To Three Objects
Method #6 – Tangent to Three Objects (TTT)
The Tan, Tan, Tan option allows you to draw a circle tangent to three existing objects.
Command: C or CIRCLE
3P/2P/TTR/<Center point>: 3P
First point: TAN
Second point: TAN
Third point: TAN
Command:
Drawing Commands

34. Circle Tangent To Three Objects
You will see a deferred tangent marker when you select the first two objects.
A deferred tangent marker means AutoCAD is aware that you have chosen those objects, but it must wait for additional input before the circle can be drawn.
Drawing Commands

35. Drawing Commands

36. Drawing Commands

37. Drawing Commands

38. Drawing Commands

39. Using Symbol
Drawing Commands

40. Using the @ Symbol The @ symbol has 3 Functions
1. To draw with relative and polar coordinates.
2. To enter the sign.
3. To input the coordinates last entered (recall LASTPOINT system variable)
Drawing Commands

41. Using Symbol
Suppose you want to draw a circle with a center at the end of the line just drawn.
The LASTPOINT system variable is set to the x,y coordinate of the end of the line.
Execute the CIRCLE command, but
Enter symbol when asked for a center point.
The center point will be located at the endpoint of the line just drawn.
Drawing Commands

42. Using Symbol
LASTPOINT system variable is set to this X, Y value with the mouse click
The LASTPOINT system variable can then be used as the center of the circle by recalling that X,Y value with symbol
Drawing Commands

43. Using Symbol
symbol automatically recalls the last coordinates as the center of the circle.
symbol retrieves the LASTPOINT system variable value.
Drawing Commands

44. Using Symbol
The LASTPOINT value is the last X,Y coordinate set clicked with the mouse when asked for graphic x,y input.
Each time you make a pick with the mouse, the LASTPOINT system variable is reset.
Drawing Commands

45. Using Symbol #2
Another application of symbol is to draw concentric circles.
Execute the CIRCLE command and draw the first circle.
Execute the CIRCLE command again, and enter symbol when asked for the center point.
Drawing Commands

46. Drawing Arcs
Drawing Commands

47. Drawing Arcs An Arc Eleven options (!) are available for drawing arcs.
Is any part of a circle or curve.
Is dimensioned with a radius.
Can be drawn a number of different ways.
Eleven options (!) are available for drawing arcs.
Drawing Commands

48. Drawing Arcs Many ways to draw arcs Three point Arc.
Start, Center, End.
Start, Center, Angle.
Start, Center, Length.
Start, End, Angle.
Start, End, Radius.
Start, End, Direction.
Center, Start, End.
Center, Start, Angle.
Drawing Commands

49. Drawing Arcs Center, Start Length of chord.
Continuing Arcs from previously drawn lines/arcs.
Drawing Commands

50. Drawing Arcs An Arc can be drawn Clockwise CounterclockwiseOR
Counterclockwise
The arc is dragged into position as the endpoint is located.
Drawing Commands

51. Drawing Arcs Three-point arc. Specify Start point
Second point along the arc
The endpoint.
Drawing Commands

52. Drawing Arcs Three-point arc Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: (select the second point on the arc)
End point: (select the arc’s endpoint)
Command:
Drawing Commands

53. Drawing Arcs Start, Center, End option
Use this option if you know the start, center, and endpoints
Picking the start and center points establishes the arc’s radius
The point selected for the endpoint determines the arc length
The selected endpoint does not have to be on the radius of the arc
Drawing Commands

54. Drawing Arcs Start, Center, End option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Center: (select the arc’s center)
Angle/Length of chord/<End point>: (select the arc endpoint)
Command:
Drawing Commands

55. Drawing Arcs Start, Center, Angle option
When the arc’s included angle is known, this may be the best choice
The included angle is the angle formed between the center, start, and endpoints of the arc
The arc is drawn counterclockwise unless a negative angle is specified
Drawing Commands

56. Drawing Arcs Start, Center, Angle option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Center: (select the arc center point)
Angle/Length of chord/<End point>: A
Included angle: 45
Command:
Drawing Commands

57. Drawing Arcs Start, Center, Length option
Standard chord lengths are specified in the chord length table (Appendix I)
Arcs are drawn counterclockwise
A positive chord length gives the smallest possible arc with that length
A negative chord length gives the largest possible arc
Drawing Commands

58. Drawing Arcs Start, Center, Length option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Center: (select the arc center point)
Angle/Length of chord/<End point>: L
Length of chord: (enter the length of the chord)
Command:
Drawing Commands

59. Drawing Arcs Start, End, Angle option
An arc can be drawn by picking the start point, endpoint, and entering the included angle
A positive included angle draws the arc counterclockwise
A negative included angle draws the arc clockwise
Drawing Commands

60. Drawing Arcs Start, End, Angle option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: E
End point: (select the arc end point)
Angle/Direction/Radius/<Center point>: L
Included angle:
Command:
Drawing Commands

61. Drawing Arcs Start, End, Radius option
A positive radius value results in the smallest possible arc between the start and end points
A negative radius gives the largest arc possible
Arcs can only be drawn counterclockwise with this option
Drawing Commands

62. Drawing Arcs Start, End, Radius option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: E
End point: (select the arc end point)
Angle/Direction/Radius/<Center point>: R
Radius: (enter value of arc radius)
Command:
Drawing Commands

63. Drawing Arcs Start, End, Direction option
Enter start point, end point and direction of rotation in degrees
The distance between the points and the number of degrees determines the arc’s location and size
The arc is started tangent to the direction specified
Drawing Commands

64. Drawing Arcs Start, End, Direction option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: E
End point: (select the arc end point)
Angle/Direction/Radius/<Center point>: D
Direction from start point:
Command:
Drawing Commands

65. Drawing Arcs Center, Start, End option
This option is a variation of the Start, Center, End option
Use this option when it is easier to begin by locating the center
Drawing Commands

66. Drawing Arcs Center, Start, End option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Start point: (select the arc center point)
Angle/Length of chord/<End point>:
Command:
Drawing Commands

67. Drawing Arcs Center, Start, Angle option
This option is a variation of the Start, Center, Angle option
Use this option when it is easier to begin by locating the center
Drawing Commands

68. Drawing Arcs Center, Start, Angle option Command: A or ARC Command:
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Center: (select the arc center point)
Start point: (pick the start point)
Angle/Length of chord/<End point>: A
Command:
Drawing Commands

69. Drawing Arcs Center, Start, Length of chord option
This option is a variation of the Start, Center, Length option
Use when it is easier to begin by locating the center
Drawing Commands

70. Drawing Arcs Center, Start, Length of chord option Command: A or ARC
Center/<Start point>: (select the first point on the arc)
Center/End/<Second point>: C
Center: (select the arc center point)
Start point: (pick the start point)
Angle/Length of chord/<End point>: L
Length of chord: (pick or type the chord length)
Command:
Drawing Commands

71. Drawing Arcs Continue arc from previously drawn line or arc.
Pick Draw, Arc, Continue from the pull-down menu
When a series of arcs are drawn in this manner, each consecutive arc is tangent
The start points and endpoints are taken from the endpoint and direction of the previous arc.
Drawing Commands

72. Drawing Arcs Continue arc from previously drawn line or arc.
The Continue option can be used to quickly draw an arc tangent to the endpoint of a previously drawn line.
Drawing Commands

73. Ellipses
Drawing Commands

74. Drawing Ellipses Ellipses have a center, and major and minor axes.
Major axis is the long axis.
Drawing Commands

75. Drawing Ellipses
Drawing Commands

76. Drawing Ellipses
When a circle is viewed at an angle, an elliptical shape is seen.
A 30o ellipse is created if a circle is rotated 30o from the line of sight.
Drawing Commands

77. Ellipses
60 degree ellipse
Circle
Drawing Commands

78. The ELLIPSE Command When drawing ellipses
Choose the appropriate option based on
the information you know about locating and constructing the ellipse.
Drawing Commands

79. The ELLIPSE Command The ELLIPSE Command Options: Center Option
Specify center
Endpoint of first axis
Endpoint of second axis
Drawing Commands

80. The ELLIPSE Command The ELLIPSE Command Options: Axis, End Option
Specify first endpoint of an axis
Second endpoint of the SAME axis
One endpoint of second axis.
The axis can be the major or minor axis
Rotation Option
Drawing Commands

81. The ELLIPSE Command The ELLIPSE Command Options: Rotation Option
Specify the angle at which a circle rotates from the line of sight.
Center
Rotation angle
Drawing Commands

82. The ELLIPSE Command Axis, Endpoint option Command: EL or ELLIPSE
Arc/Center/<Axis endpoint 1>: select an axis endpoint
Axis endpoint 2/<Second point>: select the other endpoint of the axis
<Other axis distance>/Rotation: select a distance from the midpoint of the first axis to the end of the second axis and press [Enter]
Command:
Drawing Commands

83. The ELLIPSE Command Axis, Endpoint option Command: EL or ELLIPSE
Arc/Center/<Axis endpoint 1>: (select a major axis endpoint)
Axis endpoint 2: (select the other endpoint of the major axis)
<Other axis distance>/Rotation: R
Rotation around major axis: (type a rotation angle) 30
Drawing Commands

84. Drawing Regular Polygons
Drawing Commands

85. Drawing Regular Polygons
A regular polygon is
any closed-plane geometric figure
with three or more equal sides and equal angles.
Drawing Commands

86. The POLYGON Command To draw a regular polygon. Command: POL Command:
Enter number of sides: <4>
Enter number of sides desired
Specify center of polygon or [Edge]: pick center of polygon.
Enter an option [Inscribed in circle/Circumscribed about circle] <I>: I
Specify radius of circle: specify radius with mouse
Command:
Drawing Commands

87. The POLYGON Command Inscribed Polygons
A polygon is inscribed when it is drawn inside a circle and
its corners touch the circle.
Drawing Commands

88. Inscribed
Drawing Commands

89. Drawing Regular Polygons
Circumscribed Polygons
are drawn outside of a circle
the sides of the polygon are tangent to the circle.
Specify the radius of the circle with the mouse.
Drawing Commands

90. Circumscribed
Drawing Commands

91. Drawing Regular Polygons
The Edge option
Use when location of center of polygon is unknown.
Specify first endpoint of one side of polygon
Specify second endpoint of same side of polygon
Drawing Commands

92. Drawing Polygons - Hexagons
Bolt heads and nuts on mechanical drawings are commonly drawn as hexagons and are normally dimensioned across the flats.
Draw bolt and nut polygons with circumscribed.
The radius you enter is equal to 1/2 the distance across the flats.
Drawing Commands

93. Drawing Commands

94. The RECTANGLE Command
Drawing Commands

95. Drawing Rectangles Rectangles are constructed with polylines
Can be edited with the PEDIT command.
We will learn the PEDIT command later.
A rectangle, since it is a polyline
is treated as one entity until it is exploded.
We will learn the EXPLODE command later.
Drawing Commands

96. Drawing Rectangles Rectangles are drawn with the RECTANGLE command.
Pick first corner of rectangle.
Pick second corner of rectangle.
Drawing Commands

97. Drawing Rectangles Command: REC or RECTANG Command:
Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: select the first corner
Specify other corner point or [Area/Dimensions/Rotation]: select the second corner
Command:
Drawing Commands

98. The RECTANGLE Command RECTANGLE Command Options Chamfer Fillet
Width - used to adjust the width of line of rectangle
Elevation – 3D application – not discussed here
Thickness – 3D application – not discussed here
Area
Dimensions
Rotation
Drawing Commands

99. The RECTANGLE Command RECTANGLE Command Options
Chamfer - specify by chamfer distance
Fillet - specify by fillet radius
Drawing Commands

100. Drawing Rectangles Drawing Rectangles with Line width Width option
is used to adjust the width of the line of rectangle in the X-Y plane.
Command: REC or RECTANG
Chamfer/Elevation/Fillet/Thickness/Width<First corner>: W
Width for rectangles <current> : .03
Command:
Drawing Commands

101. Drawing Commands

102. Drawing Rectangles Drawing chamfered rectangles
A chamfer is an angled corner on an object.
To draw chamfers on a rectangle use the Chamfer option.
Provide the chamfer distances.
Drawing Commands

103. Drawing Commands

104. Drawing Rectangles Drawing filleted rectangles
A fillet is a slightly rounded corner on an object.
Drawing Commands

105. Drawing Rectangles Command: REC Command:
Current rectangle modes: Fillet= Width=0.1000
Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: C
Specify first chamfer distance for rectangles <1.0000>: 2
Specify second chamfer distance for rectangles <1.0000>: 2
Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]:
Specify other corner point or [Area/Dimensions/Rotation]:
Command:
Drawing Commands

106. Drawing Commands

107. The RECTANGLE Command RECTANGLE Command Options Area Dimensions
Rotation
Drawing Commands

108. The DOUGHNUT Command
Drawing Commands

109. The DOUGHNUT Command The DOUGHNUT Command
Creates a circle with a thick line OR
A filled circle
Doughnuts drawn in AutoCAD are actually circular polylines.
Drawing Commands

110. The DOUGHNUT Command Command: DONUT (DOUGHNUT) (DO) Command:
Specify inside diameter of donut <0.5000>:
Specify outside diameter of donut <1.0000>: 2
Specify center of donut or <exit>:
Command:
A “0” inside diameter the produces a solid circle.
Drawing Commands

111. Drawing Doughnuts The FILL mode
When the FILL mode is turned off, donuts appear as segmented circles or concentric circles.
When the FILL mode is turned on, donuts appear as filled in circles.
Drawing Commands

112. Fill ON
Drawing Commands

113. Drawing Doughnuts FILL can be used transparently
Enter ‘FILL wile inside the DONUT command
Enter ON or OFF as needed.
The fill in previously drawn doughnuts remain on until the drawing is regenerated
Drawing Commands

114. Fill OFF
Drawing Commands