me-104 engineering drawing-1 -3
TRANSCRIPT
Introduction to Engineering Drawing
ENGINEERING DRAWING-IDWG-101
Aamir Naveed
Lecture # 3
Orthographic Projection
► A system of drawing views of an object using perpendicular projectors from the object to a plane of projection
Orthographic Projection
► Orthographic Projections are a collection of 2-D drawings that work together to give an accurate overall representation of an object.
Orthographic Projection
► Revolving an Object to Produce the Six Basic Views
The Glass Box
► Imagine that the object you are going to draw is positioned inside a glass box, so that the large flat surfaces of the object are parallel to the walls of the box.
From each point on the object, imagine a ray, or projector perpendicular to the wall of the box forming the view of the object on that wall or projection plane.
The Glass Box Approach
The Glass Box Approach
The Glass Box Approach
The Glass Box Approach
The Glass Box Approach
The Glass Box Approach
The Glass Box : Example
Unfolding the Glass Box
The Six Basic Views
Why must views be arranged so that they align?To make it possible for someone to interpret the drawing.
TOPREAR LEFT FRONT RIGHT
BOTTOM
The Standard Arrangement of Views
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
Which Views to Present?
Third-angle Projection
First-angle Projection
First and Third Angle Projections
► First Angle Left - Front - Bottom► Third Angle Top - Front - Right (Conventional)
plan view
end view
front view
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2006Is The Orthographic View
OK?
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2006Orthographic Must Be In
Projection
Height
Depth
Width
Front View
Top View/Plan
Right
Side View
Conventional Orthographic Views
Using a Miter Line to Transfer Depth
1. Draw miter line at 45 degrees at a convenient distance to produce the desired view.
2. Sketch light lines projecting depth locations for points to miter line and then down into side view as shown.
3. Project additional points, surface by surface.
4. Draw the view locating each vertex of the surface on the projection and miter line.
Two-View Drawings
Some objects can be fully described by two views, look for: Symmetry or Bodies of Rotation
Front View
Right Side
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2006Examples