Upload
hussein-hanoura
View
2
Download
0
Tags:
Embed Size (px)
DESCRIPTION
machine drawing
Citation preview
Engr. Faisal Nadeem Saher
PhD Research Scholar, UMP
http://saherfn.weebly.com/notes.html
BAA1112 ENGINEERING DRAWING
ORTHOGRAPHIC
LESSON OUTCOME
After this class, students should be able to do the following:
Understand the principles of first and third angle orthographic projection
Produced a detailed orthographic drawing of a component including all necessary information
ORTHOGRAPHIC PROJECTION
Engineering drawing are normally intended to indicate the shape and size of component or object
All components or objects have three dimensions; ie: length, breadth an depth
The use of technique called orthographic projection is to present the three dimensions object in two dimensions to convey an impression of shape for the component or object
ORTHOGRAPHIC PROJECTIONS
Orthographic Projections are a collection of 2-D drawings that work
together to give an accurate overall representation of an object The views are positioned relative to each other according to either
of two schemes: first-angle or third-angle projection They differ only in the position of the plan, front and side views
Third-angle Projection
First-angle Projection
First and Third Angle Projections
* Note: Only third angle is discussed in this course
First Angle Projection is used in Europe and most of the world. However America and Australia use a method known as Third Angle Projection.
1st and 3rd Angle of Projection
In First Angle Projection we place our object in the First Quadrant (see above figure). This means that the Vertical Plane is behind the object and the Horizontal Plane is underneath the object.
Defining the Six Principal Views or Orthographic
Views
Which Views to Present? Projection of view only needs combination of three
direction of views to complete the object shape; front, plan & side view
View direction is the front view of the object
General Guidelines The view with the biggest area compare to other view. Normally the longest dimension is chosen as the width (or depth) Pick a Front View that is most descriptive of object/the view with most information about the object shape
Glass Box Approach: Designation of third angle views
Place the object in a glass box
Freeze the view from each direction (each of the six sides of the box) and unfold the box
Glass Box Approach: Designation of third angle views
Glass Box Approach: Designation of third angle views
Glass Box Approach: Designation of third angle views
Glass Box Approach: Designation of third angle views
Glass Box Approach: Designation of third angle views
Glass Box Approach: Designation of third angle views
Understanding Section and Cutting Plan
Example of Orthographic Drawing [3rd Angle Projection]
Class Exercise 1 Prepare Orthographic drawing with 3rd Angle of projection using suitable scale.
Class Exercise 2 Prepare Orthographic drawing with 3rd Angle of projection using suitable scale.