ORTHOGRAPHIC PROJECTIONS
TOPIC: TECHNICAL DRAWING 2
SUB-TOPIC : ORTHOGRAPHIC PROJECTIONS
CONTENT :
INTRODUCTION
The orthographic projection of a point on a plane is given by the foot of the perpendicular from the point to the plane. A solid can be shown on a plane surface such as drawing paper.
Orthographic drawing simply means drawing at right angles.
Orthographic projection is a multi-view drawing of an object (solid) showing three faces of the object as viewed on vertical and horizontal planes.
PLANES OF PROJECTION
There are three planes of projection:
1.Horizontal Plane : Any view of an object on the horizontal plane is called PLAN.
2.Vertical Plane : Any view of the object on the vertical plane on approach is called FRONT ELEVATION.
- Side Vertical Plane : It is also a vertical plane but it is used to show the side or end views of an object. Any view of an object on this plane is called SIDE or END ELEVATION.
ANGLES OF PROJECTION
A circle is divided into four quadrants. A quadrant represents an angle of projection. Each quadrant has a horizontal and a vertical plane.
Basically, drawings are made on the first and third angles.
The second and fourth angles are not used because of tendency of drawings to overlap.