Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 1Autumn Quarter Orthographic Projection Lecture 3

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 2Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 3Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 4Autumn Quarter From Fundamentals of Graphic Communications by Bertoline, McGraw-Hill

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 5Autumn Quarter First Angle Vs. Third Angle Third-angle Projection First-angle Projection From Fundamentals of Graphic Communications by Bertoline, McGraw-Hill

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 6Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 7Autumn Quarter 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.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 8Autumn Quarter 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.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 9Autumn Quarter 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.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 10Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 11Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 12Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 13Autumn Quarter 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

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 14Autumn Quarter Remember - Six Principal Views

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 15Autumn Quarter And… Set up Conventional Three-View Height Depth Width Front View Top View Right Side View

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 16Autumn Quarter Steps in Creating the Three-View Sketch Completed Sketch

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 3P. 17Autumn Quarter Assignments Dwg 5 – A11 –Orthographic Sketches from an Isometric –Due tomorrow morning Dwg 6 – Team Agreement –Due tomorrow morning