CALENDAR
PGHS 07 OCT 04

Basic Technical Drawing /
Computer Aided Drafting I


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FreeHand Sketching
     To view lesson Objectives
    
To view Grading Criteria for Sketches (pdf)
     To view Standards Addressed

Orientation

  Sketching is drawing freehand without the aid of any drafting equipment except paper and pencil. It is a very common form of visual communication that is used in virtually ALL areas of work and life. Listed below are some of the key elements to remember about "Freehand Sketching."

  • 1. Uses no drafting equipment - freehand
  • 2. Is an extremely fast form of visual communication.
  • 3. Sketches increase clarity and understanding of concepts, shapes, or directions.
  • 4. Is very convenient - can be done anywhere.
  • 5. Is an extremely valuable organizational tool, which helps to minimize or prevent errors.
  • 6. Is a collection of all necessary information required about an object - including detail, size and shape descriptions.
  • Critical Factors

    A. Key Reasons for Sketching
         1) Communicate
         2) Organize
         3) Realize Ideas

    B. Key Factors while Sketching
         1) Speed
         2) Accuracy
         3) Clarity

    Basic Elements

    A. Lines
         1) Construction
         2) Object
    B. Simple Shapes
         1) Squares, rectangles, triangles, polygons, etc...
    C. Objects
         1) A collection of simple shapes and details.

    Drawing Methods

    A. Construction Lines to Object Lines
        
    1) ALL single lines - NO "fuzzy" art type lines!
         2) Point to Point
         3) Dash to Dash
         4) Draw Left to Right OR Bottom to Top

    B. Block Technique
        
    1) Establish outer proportions of object(s)
         2) Divide into areas of major shapes
         3) Add detail as required
         4) Add text where necessary to clarify (notes or
              dimensions)

    C. Graph Technique (Resizing or Duplicating an Original)
        
    1) Use original photo or drawing OR a xerox copy.
         2) Draw Horizontal & Vertical grid lines on top of
              object spaced an exact distance apart (ex. ",
              ", etc.).
         3) On clean sheet of paper reproduce grid at
              desired size (enlarge / reduce)
         4) Add line detail a block at a time.

    D. Evaluation of Freehand Sketches
        
    1) Use and lightness of construction lines.
         2) Views in correct positions and aligned.
         3) Use of block technique to box in basic shapes.
         4) Use of text notes on every sketch.
         5) A reasonable reproduction of original.

    Types of Sketches / Assignments

    A. One View Orthographic Projection
        
    1) Always that view which would be considered the
              front of the object.
         2) Used when only one view is necessary to provide
              shape description.
    B. Two View Orthographic Projection
        
    1) Front View and Top View.
         2) Used for cylindrical objects when all side views
              are identical.
    C. Three View Orthographic Projection
        
    1) Front View, Top View, and Right Side View
         2) Provides the most complete shape and size
              description.
         3) Is the industry standard for the manufacture of
              objects.
    D. Enlargement / Reduction
    (Templates)
         1) Use of graph paper to enlarge or reduce grid
              size
         2) Complete sketch square by square, comparing
              individual squares as you proceed.
     E. Realize Ideas / Designing
        
    1) Front View, Top View, and Right Side View
         2) Clarity is essential, use text notes whenever
              necessary.
         3) Be sure finished sketch reflects what is in your
              mind.