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Orthographic Projection

Orthographic Projection. Lecture 3. Today’s Activities . Today More On Multi-view Orthographic Drawings BTG Chap 4 Orthographic Projection Teamwork Workshop Tomorrow Learn how to do isometric drawings First AutoCAD Lesson. Projection Methods (BTG pg 123). Perspective projections

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Orthographic Projection

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  1. Orthographic Projection Lecture 3 Autumn Quarter

  2. Today’s Activities • Today • More On Multi-view Orthographic Drawings • BTG Chap 4 • Orthographic Projection • Teamwork Workshop • Tomorrow • Learn how to do isometric drawings • First AutoCAD Lesson Autumn Quarter

  3. Projection Methods (BTG pg 123) • Perspective projections • Linear 1, 2, or 3 Vanishing points • Aerial • Parallel projections • Oblique projection: cavalier, cabinet, or general • Orthographic projection • Axonometric • Isometric, dimetric, or trimetric • Multi-view • First-angle or third-angle Autumn Quarter

  4. From Fundamentals of Graphic Communications by Bertoline, McGraw-Hill Autumn Quarter

  5. Third-angle Projection First-angle Projection First Angle Vs. Third Angle From Fundamentals of Graphic Communications by Bertoline, McGraw-Hill Autumn Quarter

  6. Review - Why Multi-view?Give 3 reasons • Most accurate description of 3-D objects for engineering, manufacturing, and construction • Dimensions of features are presented in true size in one or more views • Easy transition to 3-D database and computer modeling Autumn Quarter

  7. Principals Of Orthographic Projection • Every point or feature must be aligned on a parallel projector in any adjacent view. • Distances between any two points in a related view must be equal. • Features are true length or true size when the lines of sight are perpendicular to the feature. Autumn Quarter

  8. Principals Of Orthographic Projection • Features are foreshortened when lines of sight are not perpendicular to the feature. • Areas that are the same feature will always be similar in configuration from one view to the next, except when viewed on the edge. - Example: Triangular surface always has three sides in all views • Parallel features will always appear parallel in all views. Autumn Quarter

  9. Principals Of Orthographic Projection • Surfaces that are parallel to the lines of sight will appear as lines or edge views. • No two contiguous (adjacent) areas can lie in the same plane. Autumn Quarter

  10. Hints For Multiview Sketching • Identify the major features and overall dimensions of the object • Do not use your scale as a pencil guide when sketching by hand • Start by drawing bounding boxes with light construction lines. • Keep views aligned while sketching Autumn Quarter

  11. Hints For Multiview Sketching • Only measure along the primary axes fi you are working from a pictorial. • Map inclined and oblique faces among all three views • Follow the precedence of lines • Darken all visible, hidden, and center lines Autumn Quarter

  12. Defining Hidden and Center Lines • Hidden Line – used to represent features that cannot be seen in the current view • Centerlines – used to represent symmetry and to mark the center of circles and the axes of cylinders, and the axes of symmetrical parts, such as cylinders and bolts Autumn Quarter

  13. Precedence of Lines VISIBLE LINES takes precedence over hidden and center lines HIDDEN LINES take precedence over center lines CENTER LINE does not have precedence Autumn Quarter

  14. Remember - Six Principal Views Autumn Quarter

  15. Width Depth Top View Right SideView Front View Height And… Set up Conventional Three-View Autumn Quarter

  16. Steps in Creating the Three-View SketchCompleted Sketch Autumn Quarter

  17. Assignments • Dwg 5 – A11 • Orthographic Sketches from an Isometric • Due tomorrow morning • Dwg 6 – Team Agreement • Due tomorrow morning Autumn Quarter

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