This document discusses isometric projection and drawing techniques in engineering graphics. It covers topics such as isometric axes, scales, views, and methods for drawing the isometric projections of planes, prisms, pyramids, and objects with non-isometric lines. Examples are provided to illustrate how to draw isometric views given orthographic projections of various objects.
2. Isometric projection
Pictorial representation of a 3D solid in one view.
The actual sizes can be measured directly from the view.
Isometric axes.
Isometric lines.
Isometric planes.
Isometric scale.
1 2
cos30 3
BA
BO
1 2
cos45 1
BP
BO
2 9
0.815
3 11
BA
BP
3. Isometric scale
The lines which are not to the isometric axes are not reduced according to any fixed
ratio. Such lines are called non-isometric lines.
4. Isometric view
The view drawn with the true scale is called isometric view or isometric drawing.
The view drawn with the isometric scale is called isometric projection.
Each horizontal face will have its sides to the
to sloping axes.
Each vertical face will have its vertical sides to
the vertical axis and the other sides to one of the
sloping axes.
5. Isometric drawing of planes
The front view of a square is given. Draw its isometric view.
6. Isometric drawing of planes
The top view of a square is given. Draw its isometric view.
7. Isometric drawing of planes
The front view of a hexagon whose surface is to the V. P. is given. Draw its isometric
view.
Box method
8. Isometric drawing of planes
The front view of a circle whose surface is to the V. P. is given. Draw its isometric view.
Method of points
9. Isometric drawing of planes
The front view of a circle whose surface is to the V. P. is given. Draw its isometric view.
Four-centre method
10. Isometric drawing of planes
The front view of a semi-circle whose surface is to the V. P. is given. Draw its isometric
view.
11. Isometric drawing of planes
Figure below shows the F. V. of a plane to the V. P. Draw its isometric view.
12. Isometric drawing of prisms and pyramids
Draw the isometric view of a square prism, side of the base 20 mm long and axis 40 mm
long, when its axis is vertical.
13. Methods of drawing non-isometric lines
Three views of a block are given. Draw its isometric view.
Box method
14. Methods of drawing non-isometric lines
Co-ordinate or offset method:
Used for objects in which neither non-isometric lines nor their ends lie in isometric
planes.
ヰ
s are dropped from each end of the edge to a horizontal or vertical reference plane. The
points at which the ヰ
s meet the plane, are located by drawing co-ordinates or offsets to the
edges of the plane.
15. Co-ordinate or offset method
Draw the isometric view of the truncated triangular pyramid shown below.