06 H191 W02 D02 1 V1 4 Projection Systems Ortho an

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Engineering H191 Engineering Fundamentals and Laboratory I: 

Engineering H191 Engineering Fundamentals and Laboratory I Week 02 Day 02 Projection Systems: Orthographic and Isometric

Objectives: 

Objectives Orthographic Projections View Selection Glass Box Approach First and Third Angle Projections Line Precedence Two View Drawings Tips

Orthographic Projections: 

Orthographic Projections Reference: Technical Graphics, Chap 3: Advantage – Represent features of an object more accurately Example Problem

Orthographic Projections: 

Orthographic Projections Orthographic Projections are a collection of 2-D drawings that work together to give an accurate overall representation of an object.

Defining the Six Principal Views or Orthographic Views: 

Defining the Six Principal Views or Orthographic Views

Which Views to Present?: 

Which Views to Present? General Guidelines Pick a Front View that is most descriptive of object Normally the longest dimension is chosen as the width (or depth) Most common combination of views is to use: Front, Top, and Side View Any other view different from the Principal Views is called an Auxiliary View (see 3.15 in the Technical Graphics text)

Glass Box Approach: 

Glass Box Approach Most powerful technique to understand orthographic projections Suspend the object with transparent strings inside a glass box Freeze the view from each direction (each of the six sides of the box) and unfold the box Animation illustrates glass-box approach

Glass Box Approach: 

Glass Box Approach Available on the FEH website: http://feh.osu.edu Lecture Notes Engineering H191 – Autumn 2006 Glass Box Animation

Glass Box Approach: 

Glass Box Approach

Glass Box Approach: 

Glass Box Approach

Glass Box Approach: 

Glass Box Approach

Glass Box Approach: 

Glass Box Approach

Glass Box Approach: 

Glass Box Approach

Glass Box Approach: 

Glass Box Approach

First and Third Angle Projections: 

First and Third Angle Projections First Angle – International Third Angle – U.S.

Conventional Orthographic Views: 

Conventional Orthographic Views

Is The Orthographic View OK?: 

Is The Orthographic View OK?

Orthographic Must Be In Projection: 

Orthographic Must Be In Projection

Hidden and Center Lines: 

Hidden and Center Lines

For Example:: 

For Example: 1. Visible 2. Hidden 3. Center

Precedence of Lines: 

Visible lines takes precedence over all other lines Hidden lines and cutting plane lines take precedence over center lines Center lines have lowest precedence Precedence of Lines

Example: Application of Precedence : 

Example: Application of Precedence

Intersecting Lines in Orthographic Projections: 

Intersecting Lines in Orthographic Projections Solid Line Intersections Dashed Line Special Case Intersections

Two-View Drawings: 

Two-View Drawings Some objects can be fully described by two views, look for: Symmetry or Bodies of Rotation Front View Right Side View Front View Right Side

Other Two-View Examples: 

Other Two-View Examples

Summary: 

Summary Introduced to orthographic projections We recommend the software animation exercise introduced in class. Animation can be found on Carmen – Glass Box Theory.

Review Questions: 

Review Questions Rectilinear grids are used for sketching isometric pictorials … True/False Based on the lines of sight, orthographic projection drawings are classified as ___________ projections There are ____ standard principal views of orthographic projections Each view in an orthographic projection concentrates on ____ dimensions of the object

Hints for Orthographic Projection Sketching: 

Hints for Orthographic Projection Sketching Identify the major features and overall dimensions of the object Do not use any straight-edge devices as a pencil guide when sketching by hand Start by drawing bounding boxes with light construction lines. Keep views aligned while sketching

Hints for Orthographic Projection Sketching: 

Hints for Orthographic Projection Sketching Title Information is required – follow conventions Usage of construction lines is encouraged. Mandatory for circle or ellipse Orthographic projection: Alignment of the views is important! Will not be graded, if not aligned

Hints for Orthographic Projection Sketching: 

Hints for Orthographic Projection Sketching Map inclined and oblique faces to all three views Follow the precedence of lines Darken all visible, hidden, and center lines

Sketching a Circle: 

Sketching a Circle Draw a square whose sides are the diameter of the circle. At the center of each side define the point of tangency for the circle. Draw the diagonals of the square. Orient the paper so you can draw equal arcs to construct the circle

Today's Assignment: 

Today's Assignment B11 TG 2.10 and 2.19

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