Objective 4.05 Explain computer processes used in computerized 2D/3D modeling

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Objective 4.05 Explain computer processes used
in computerized 2D/3D modeling
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Computer Aided Design (CAD)

• A computer is a valuable technology tool. A
  common industrial application for computer
  systems is in preparing drawings and models.

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Computer Aided Design (CAD)

• CAD refers to the process that uses a computer
  and drawing software to assist the drafter in
  preparing mechanical and architectural drawings.

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Advantages of CAD

• Speed
• Quality
• Ease of modification
• Cost reduction

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Speed

• A drafter can produce more drawings in a given
  amount of time than using traditional drafting
  methods.

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Quality

• The overall quality of a design is improved by
  increasing line quality, neatness, legibility,
  and accuracy.

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Ease of modification

• CAD drawings are stored in memory and can be
  recalled and modified easily.

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Cost

• All of the previously listed reasons make CAD
  more cost effective than traditional drafting.

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The number of dimensions greatly affects the
ability to view and display pictorial views of
the object.
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Basic categories of CAD

• 2D packages store data for the X and Y
  coordinates only.
• 2.5D packages also store data points for the X
  and Y coordinates, but they also provide
  simplified 3D visualization for objects.
• 3D programs store X, Y, and Z coordinates of each
  data. A three dimensional database for each point
  of an object. The z axis represents the vertical
  axis in3 D modeling.

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3D Systems Stereo Lithographic Apparatus (SLA)

• SLA produces full-size, 3D plastic models
  directly from CAD drawings.

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CAD Terminology

• Commands- short words which, when entered, causes
  the computer to perform some function

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CAD Terminology

• Entity an object or text item created using CAD
  software

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CAD Terminology

• Grids-The grid dots assist the drafter in drawing
  entities. Most programs allow the drafter to
  adjust the spacing of the dots. This is referred
  to as grid spacing.

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CAD Terminology

• Snap Grids-When snap grid is on, the cursor jumps
  from grid point to grid point as it moves across
  the screen. With snap grid, the cursor can only
  be positioned at a grid point. Without snap
  grid, the cursor glides across the screen.

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CAD Terminology

• Rotation-The entity can be rotated by specifying
  a specific angle of rotation, or it can be
  rotated by grabbing on corner of the entity
  (called a handle point) and dragging that point
  around the base point.

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CAD Terminology

• Zoom-allows the drafter to move into a particular
  part of a drawing. By moving in on the drawing,
  the drafter can view more details. This function
  is extremely useful when working with very
  detailed drawings.

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CAD Terminology

• Tool bar a collection of tool buttons grouped
  together.

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CAD Terminology

• Windows- most CAD programs allow the screen to be
  split into separate windows. Each window is a
  separate display screen. The windows function is
  useful when working on very large drawings.

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Cartesian Coordinates System

• A method of graphical point location. All CAD
  systems use this system as a standard. It allows
  precise positioning of entities on the drawing
  surface.

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Coordinate pair

• Represents the position of a point. The first
  number represents the X coordinate while the
  second is the Y coordinate.

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X,Y, Coordinate

• The X coordinate is the point's distance from the
  origin along the X axis. The Y coordinate is the
  point's distance from the origin along the Y
  axis. The origin is the intersection of the two
  axes. The intersection of the X and Y axes
  creates four quadrants for plotting points.

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• Notice, X and Y points in quadrant I are
  positive. In quadrant 2, X is positive and Y is
  negative. In quadrant 3, both X and Y are
  negative, while in quadrant 4, X is negative and
  Y is positive.

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Absolute Coordinates

• Give the position measured from the origin of the
  drawing. Absolute coordinates refer to precise
  locations on the Cartesian coordinate grid. For
  example, coordinates of 4,2 defines a point four
  units to the right and two units above the
  origin.

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Relative Coordinates

• Refer to a point or location measured from a
  previous point. For example, coordinates could be
  specified for a second point that is at 8,4 from
  the original point 4,2. To plot this second
  point, you would move eight units to the right
  and four units above the point 4,2. The absolute
  coordinates for this second point would be 12,6.