TECHNICAL

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TECHNICAL SKETCHING
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Drafting

• The Universal Language
• Drafting is the process of accurately
  representing three-dimensional objects and
  structures on a two-dimensional surface, usually
  paper.
• An accurate drawing process used for nearly every
  product or structure made today large or small.
• Drawings are also used to communicate ideas
  effectively and accurately.

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Sketching

• Rough Sketches are the most common recording
  method. The term rough describes the state of
  the design ideas. It suggests that the designs
  are incomplete and unrefined.
• Refined Sketches are refined design ideas. They
  may not look anything like the original rough
  sketches.
• Detailed Sketches communicate size, in addition
  to the shape and proportion communicated in the
  first two drawings. It also communicates the
  information needed to build a model of the
  product or structure.

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Pictorial Sketches
Different techniques are used to show the
artifact as the human eye would see it.
Therefore, a single view is used to show how the
front, sides, and top would appear.
Perspective Sketches
Oblique Sketches
Isometric Sketches
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Pictorial Drawings
Pictorial drawings show several sides at the same
time.  Many people find pictorial drawings easier
to understand.  They do not provide as much
information as orthographic views. 
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Oblique Sketches

• The easiest pictorial sketches to produce.
• Show the front view as if you were looking
  straight at it.
• Sides extend back from the front view.
• Sides shown with parallel lines that are
  generally drawn at 45 degrees to the front view.

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Oblique Sketches

• Cavalier Oblique drawings cause the sides and top
  to look deeper than they are.
• Cabinet Oblique drawings shorten the lines that
  project back from the front to one-half their
  original length.

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Isometric Sketches
Isometric means equal measure.
Angles formed by the lines at the upper right
corner are equal to 120 degrees.
Object is shown as if viewed from one corner.
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Isometric Sketches
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Isometric Sketches
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Isometric Sketches
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Perspective Sketches

• Show how the human eye and camera would see it.
• Realism is obtained by having parallel lines meet
  at a distance vantage point.
• Most realistic, yet, most difficult of the three
  sketches.

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Types Of Perspective

• Three major types one-point, two-point, and
  three-point.
• One-point perspective shows an object as if you
  were directly in front of it.
• Two-point perspective shows how an object would
  appear if you stood at one corner.
• Three-point perspective shows how the eye sees
  the length, width and height of an object.

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1 POINT PERSPECTIVE
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1 POINT PERSPECTIVE
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2 POINT PERSPECTIVE
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3 POINT PERSPECTIVE
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3 POINT PERSPECTIVE
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Detail Drawings

• Most are prepared using the multi-view method.
• This method places one or more views of the
  object in one drawing.
• Generally, a top, right side, and end view are
  shown.
• Multi-view drawings use orthographic projection
  to project information at the right angles to new
  views.
• Front view is drawn in the lower left quadrant of
  the paper.
• Projection lines are extended to the top and
  right of a front view to form the top and side
  views.

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Orthographic Drawings

• Orthographic views are two-dimensional drawings
  used to represent or describe a three-dimensional
  object. The ortho views represent the exact shape
  of an object seen from one side at a time as you
  are looking perpendicularly to it without showing
  any depth to the object

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Orthographic Drawings

• Primarily, three orthographic views (top, front,
  and right) adequately depict the necessary
  information to illustrate the object.

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Drawing Lines
Different lines are used to show the outlines and
major details on an object. Object lines are the
darkest lines which show the outlines and major
details. Hidden lines are dotted lines used to
show outlines which are not visible in a certain
view. Center lines locate holes in a part.
These lines pass through the center of the
hole. Extension lines, used in dimensioning,
indicate the points from which the measurements
are taken. Between the extension lines are the
dimension lines. These have arrows pointing to
the extension lines that indicate the range of
the dimension.
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Computer Aided Drafting

• CAD is used in every drafting discipline.
• Mechanical Engineering
• Architectural Engineering
• Construction
• Electrical Engineering
• 2 Dimensional
• AutoCAD
• CADD
• 3 Dimensional
• Solid Works
• 3D Studio

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Computer Aided Drafting

• CAD (Computer-Aided Design) refers to a process
  that uses a computer and drawing software to
  assist the drafter in preparing mechanical or
  architectural drawings. CADD (Computer-Aided
  Design and Drafting) is closely related to CAD.
• CADD systems use extra functions that simulate
  testing products. Professional designers use CADD
  to increase the quality of their work.

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Cartesian Coordinate 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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Computer Aided Drafting

• The graphic primitives are defined geometrically
  in terms of the normal Cartesian Coordinate
  System (right-handed system with positive X-axis
  to the right, positive Y-axis up the screen and
  positive Z-axis coming out of the screen towards
  the user).

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Computer Aided Drafting

• Advantages of CAD - The heart of a CAD system is
  the computer. A computer is capable of producing
  drawings much faster than humans. Computers can
  be programmed to perform certain complex
  functions with just the push of a single key. A
  traditional drafter may have to complete dozens
  of pencil strokes to perform the same function.
  Computers are generally more accurate than
  humans, and they can perform the same function
  over and over without errors or deviations. CAD
  has several advantages over traditional drafting
  methods.
• Four advantages of CAD are speed, quality, ease
  of modification, and cost.

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CAD Terminology

• Commands- short words which, when entered, causes
  the computer to perform some function.
• Entity-an object or text item created using CAD
  software.
• Grids-help the drafter easily locate position on
  the drawing. They are used like lines on graph
  paper. The grid assists the drafter in drawing
  entities. Most programs allow the drafter to
  adjust the spacing of the dots. This is referred
  to as grid spacing.
• Snap Grids-is used to lock the drawing cursor to
  grid points as it is moved across the screen.
  When snap grid is on, the cursor jumps from grid
  point to grid point as it moves across the
  screen.

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CAD Terminology

• Rotation-used to rotate an entity around a base
  point.
• Zoom-allows the drafter to move in on 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.
• 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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Solid Works