2. Section 1 Introduction to Drafting
Chapter 4
CAD Commands and Functions
Section 1 Introduction to Drafting

3. Objectives
List several general categories of commands used in popular CAD programs.
Explain how points and objects are located using a coordinate system.
Explain the use of linear, angular, and leader dimensioning.
Identify and describe drawing aids.
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4. Objectives Discuss the purposes of colors, linetypes, and layers.
Explain layer naming conventions as related to CAD drawings.
Describe 3D drawing.
Explain rendering.
Explain animation.
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5. Types of CAD Commands File management Drawing Editing Display control
Dimensioning
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6. Command Entry Methods Pull-down menus Toolbars Command line Tablet
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7. File Management Commands
Used to create, save, or open file.
Files may originate from scratch or template.
Drawings should be saved every 10 to 15 minutes.
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8. Coordinate Systems Used to specify point locations for objects.
Cartesian coordinate system is most common.
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9. Cartesian Coordinate System
X axis and Y axis used to locate points.
Points designated as (X,Y).
XY drawing plane sufficient for 2D work.
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10. Types of Coordinate Entry
Absolute coordinates
Relative coordinates
Polar coordinates
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11. Absolute Coordinates Measured from origin (0,0).
Most basic way to locate points.
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12. Relative Coordinates Used to locate point from previous point.
Designated symbol.
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13. Polar Coordinates
Used to locate points at relative distance and angle.
Angles typically measured from 0 horizontal.
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14. Three-Dimensional Coordinates
Z axis used to define “vertical” measurement.
Points designated as (X,Y,Z).
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15. User Coordinate System (UCS)
Used to establish different origin from world coordinate system.
Commonly used with 3D drawing functions.
Created with UCS command.
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16. Drawing Commands Line Double Line Point Circle Arc Spline Ellipse
Rectangle
Polygon
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17. Line Command Used to draw straight lines. Two points specified.
Coordinates entered or picked on screen.
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18. Double Line Command Used to create parallel lines.
Allows user to set distance between lines.
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19. Point Command Used to create point objects.
Helpful for construction purposes.
Visibility modes used to change display.
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20. Circle Command Used to create circles based on user input.
Center and radius
Center and diameter
Three points
Two points
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21. Arc Command Used to create arcs based on user input. Three points
Start, center, end
Start, center, angle
Start, center, chord length
Start, end, radius
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22. Spline Command Provides several ways to create spline.
Picking points along curve.
Converting existing lines into spline.
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23. Ellipse Command Used to create ellipse.
Points specified for major and minor axes.
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24. Rectangle Command Provides several methods for drawing rectangles.
Width and height
Opposite corners
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25. Polygon Command Provides several options to create regular polygon.
Circumscribed
Inscribed
Side length
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26. Text Command Used to create text objects. Allows text font to be set.
Provides justification and rotation options.
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27. Hatch Command Used to “hatch” areas in section views.
Provides selection of standard material patterns.
Internal areas typically picked for hatching.
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28. Editing Commands Erase Undo Move Copy Mirror Rotate Scale Fillet
Chamfer
Trim
Extend
Array
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29. Mirror Command Used to “mirror” objects about mirror axis.
Useful for symmetrical features.
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30. Fillet Command Used to create fillet or round.
Creates radial curve between two selected objects.
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31. Chamfer Command Used to chamfer corners.
Operation similar to Fillet command.
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32. Array Command Used to copy objects in rectangular or polar pattern.
Rows, columns, and offset specified for rectangular array.
Number of objects, center point, and angle specified for polar array.
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33. Arrays
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34. Inquiry Commands List Properties Distance Area
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35. List and Properties Commands
Used to display object data.
Coordinates
Line lengths
Layer assignments
Linetype settings
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36. Area Command Used to make area and perimeter calculations.
Points picked to define enclosed area.
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37. Display Control Commands
Zoom
Pan
View
Redraw
Regenerate
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38. Zoom Command Used to enlarge or reduce display of objects.
Does not change actual size of objects.
Allows “real time” zooming and specified magnification factor.
Useful for “zooming in” on object details.
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39. Pan Command Used to move drawing on screen. Does not “zoom” drawing.
Helpful for large drawings with objects “off” screen.
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40. View Command Used to save current display of drawing.
Allows restoring certain display without zooming or panning.
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41. CAD Dimensioning Provides major advantage over manual drafting.
Permits flexibility for placement of text and dimension elements.
Types of commands relate to dimension method and content.
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42. Dimensioning Commands
Linear
Angular
Diameter
Radius
Leader
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43. Drawing Aids
Grid
Snap
Ortho
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44. Grid Used to show display grid on screen.
Composed of configuration of dots.
Provides visual cue for drawing size and spacing.
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45. Snap Permits alignment of cursor with specific points on screen.
Useful for “connecting” to endpoints, intersections, and centers.
Provides critical tool for ensuring accuracy of point locations.
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46. Types of Snap
Grid snap
Object snap
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47. Common Object Snaps Endpoint Center Midpoint Perpendicular Tangent
Intersection
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48. Ortho Forces lines to be drawn horizontally or vertically.
Useful when lines must be drawn “square.”
Must be deactivated to draw inclined lines.
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49. Layers Similar to overlays in manual drafting.
Each object has assigned layer.
Used to control visibility of drawing content.
Usage typically regulated by company or industry standards.
Same naming conventions should be followed by everyone working on project.
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50. Display Colors Typically assigned to layers to identify content.
Useful for distinguishing dimensions and text from object lines.
Usage often dictated by layer standards.
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51. Linetypes Used to follow conventions in Alphabet of Lines.
Scale settings used to control appearance.
Assigned by layer or by object type depending on standard practice.
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52. Blocks Provide way to store drawing symbols for repeated use.
Typically saved to symbol library.
May include attribute definitions to indicate different sizes and types.
Used to generate schedules when created with attributes.
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53. Block and Attributes
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54. 3D Drawing Functions
Used for creating realistic representations of objects.
Available in more advanced programs.
Include analysis tools in some manufacturing applications.
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55. Isometric Drawing
Shows object in 3D, but it is actually two-dimensional.
Typically made using isometric grid and snap.
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56. Types of 3D Modeling Surface modeling Solid modeling
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57. Surface Modeling Creates 3D objects by giving wireframe “skin.”
Used for rendering and animation.
Not typically used in manufacturing applications.
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58. Solid Modeling Most realistic form of 3D modeling.
Permits testing for manufacturing purposes.
Rendering and animation functions typically supported.
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59. 3D Viewing Functions Preset isometric views Dynamic rotation
Hide command
Preset isometric views
Dynamic rotation
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60. User Coordinate Systems
Used to establish 3D drawing planes for modeling.
Particularly useful for models with many surfaces.
Icon used to identify system origin and orientation of XYZ drawing axes.
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61. User Coordinate Systems (Cont.)
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62. 3D Animation and Rendering Commands
Material
Used to define and apply surface textures to objects
Render
Used to “color” the drawing
Animate
Used to add movement to objects
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63. Rendered Model
(Bucyrus International)
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64. Review Questions
Distances, areas, and perimeters can be calculated using _____ commands.
A. editing
B. drawing
C. inquiry
D. file management
C. inquiry
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65. Review Questions
2. The _____ command is used to create a smooth curve through a series of points.
A. Line
B. Ellipse
C. Spline
D. Hatch
C. Spline
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66. Review Questions
3. The _____ command is used to reverse the last command operation.
A. Undo
B. Erase
C. Move
D. Copy
A. Undo
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67. Review Questions
4. The _____ command is used to create multiple copies of objects in rectangular or circular patterns.
A. Scale
B. Rotate
C. Layer
D. Array
D. Array
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68. Review Questions
5. The _____ command is used to enlarge or reduce the drawing display by changing the magnification factor.
A. Scale
B. Zoom
C. Pan
D. Hatch
B. Zoom
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69. Review Questions
6. _____ coordinates define point locations at a given distance and angle from a fixed point.
Polar
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70. Review Questions
7. A(n) _____ dimension measures the distance from the center of an arc to a point on that arc.
radius
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71. Review Questions
8. The _____ function allows you to align the cursor with points on screen.
A. snap
B. ortho
C. grid
D. redraw
A. snap
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72. Review Questions
9. A _____ is a virtual piece of paper on which objects are placed.
A. grid
B. hatch
C. layer
D. block
C. layer
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73. Review Questions
10. A(n) _____ is text information saved with a block.
A. layer
B. hatch
C. grid
D. attribute
D. attribute
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74. Review Questions
11. The _____ command is used to “color” a drawing for presentation purposes.
A. Render
B. Layer
C. UCS
D. Hatch
A. Render
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75. Review Questions
12. A(n) _____ drawing is a 2D drawing that shows a 3D representation of an object.
isometric
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76. Review Questions
13. A(n) _____ is a series of still images played sequentially at a fast rate.
animation
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77. Glossary Absolute coordinates Animation
Exact point locations measured from the coordinate system origin.
Animation
A series of still images played sequentially at a very fast rate to simulate motion.
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78. Glossary Attribute Block
In CAD applications, a string of text used to list information about a block in a drawing.
Block
In CAD applications, a predrawn symbol designed for multiple use, representing an object that can be inserted into a drawing.
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79. Glossary Cartesian coordinate system Command
A standard point location system typically used in a CAD system to define positions in space.
Command
An instruction to a computer that achieves a function when entered.
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80. Glossary Display grid Drawing aids
In CAD applications, a framework of dots displayed to serve as a reference for locating points at measured distances.
Drawing aids
CAD tools that simplify the tasks of locating positions on screen and on existing objects.
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81. Glossary Ellipse Fillet A closed circular object with an oval shape.
A small, rounded, internal corner.
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82. Glossary Isometric drawing
A pictorial drawing of an object positioned so that all three axes make equal angles with each other. Measurements on all three axes are made to the same scale.
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83. Glossary
Layer
On a CAD drawing, user-defined settings that permit the various parts of a drawing to be separated into different layers or “sheets,” much like the transparent drawing sheets in overlay drafting.
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84. Glossary Object snap Origin
A CAD drawing aid that allows the cursor to “jump” to certain locations on existing objects.
Origin
The “zero point” of the Cartesian coordinate system.
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85. Glossary Ortho Polar coordinates
A CAD drawing mode that forces all lines to be drawn orthogonal (vertical or horizontal).
Polar coordinates
Point locations measured by entering a given distance and angle from a previous point.
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86. Glossary Regular polygon Relative coordinates
An object with sides of equal length and included angles.
Relative coordinates
Point locations measured from a previous point.
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87. Glossary Rendering Round Snap
Finishing a presentation drawing to give it a realistic appearance. The term rendering also refers to the actual drawing.
Round
A small, rounded, external corner.
Snap
A CAD drawing aid that allows the cursor to “grab on to” certain locations on screen.
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88. Glossary Spline Symbol library
A smooth curve that passes through a series of points.
Symbol library
In CAD applications, a collection of standard shapes and symbols typically grouped by application for use on drawings.
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89. Glossary Template X axis
In CAD applications, a drawing file with preconfigured user settings.
X axis
The horizontal coordinate axis used to locate points in the Cartesian coordinate system.
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90. Glossary
Y axis
The vertical coordinate axis used to locate points in the Cartesian coordinate system.
Z axis
The coordinate axis used to locate points in relation to the XY drawing plane in three-dimensional drawing.
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