Module 2 Geometric Construction · PDF fileAutoCAD 2D-1 . Module Objectives Upon the...
Transcript of Module 2 Geometric Construction · PDF fileAutoCAD 2D-1 . Module Objectives Upon the...
AutoCAD 2D-1
Module Objectives
Upon the completion of this module the student will be
able to:
1. Explain the difference between Isometric and
oblique drawing.
2. Correctly produce an isometric drawing for cubes,
circles, and cylinders.
3. Draw isometric drawings for a combination of
cubes, circles, and cylinders.
Module Contents
Topic Page no.
1 Introduction page 3
2 Types of Pictorial drawing page 3
3 Isometric drawing page 4
4 Activities page 8
Introduction
The pictorial drawing is a three dimensional drawing
that shows an object’s three principal planes, much as
they would be captured by a camera.
2. Types of Pictorial drawing:
There are three types of pictorial drawings:
A. Isometric
B. Oblique, and
C. Perspective.
In this module only Isometric and Oblique will be dealt with.
2.1 Isometric.
Isometric drawing represents an object in three dimensions.
It helps to visualize the features of an object on at
least three sides.
The three axes forms an angle of 120 degrees between one another. See Fig.3.1.
2.2 Oblique.
Oblique projection is a method of drawing objects in 3
dimensions.
It is quite a simple technique compared to isometric drawing.
In the Oblique drawing instead of the two 30 degrees guide lines, there are one horizontal line and one 45 degree guidelines.
There are two types of oblique drawing as
shown in Fig.3.2. (a) Cavalier. (b) Cabinet.
Fig.3.1: Isometric
drawing in full scale
Fig.3.2:Types of
Oblique drawing
3. Isometric drawing
3.1 Isometric drawing of a cube
1. Draw two basic 30 degree (to the horizontal line)
guidelines, one to the left and one to the right, plus a
vertical guideline in the centre of the drawing as
shown in Fig.3.3. This will guide the isometric drawing of
the cube. The required tools are shown in Fig.3.3a.
2. Draw guidelines to help start constructing the left and
right sides of the cube. Remember to use a 30 degree
set square for the 'angled' lines. Fig.3.4.
(a)
(b)
Fig.3.3: Isometric
drawing
Fig.3.4: Isometric drawing
of a cube
3. The top of the cube can be drawn quite easily by using the set square
to draw one edge of the top and then ‘flipping’ it over to draw the
other. See Fig.3.5.
Fig.3.5: Drawing the top
of the cube
4. The Final isometric drawing of the cube is shown in Fig. 3.6.
Fig.3.6: Final Isometric drawing
of the cube
3.2 Isometric drawing of circles and cylinders
1. Construct an isometric square 60 mm by 60mm
mm using 30, and 60 degree set square as
shown in Fig.3.7. The isometric square will be
used to draw the isometric circle.
2. Construct a perpendicular bisector from each
side of the isometric square, then draw two
perpendicular bisectors (center lines) from each
midpoint as shown on the Fig.3.9.
Fig.3.7: Isometric
Square
Fig.3.8: Constructing
bisectors
3. Locate the two centers. By campus,
draw the two arcs as shown on the
Fig.3.9.
4. Draw the arcs with these centers and
tangent to isometric square. The final
front side isometric circle (ellipse) is shown
on the Fig.3.10.
Fig.3.9: Locating the
centers and drawing the
arcs.
Fig.3.10: Completing
the ellipse
5. The isometric circle (Ellipse) in Front, Right and Top views is
shown in Fig.3.11.
6. Drawing an isometric cylinder will be simply by drawing two
isometric circles opposite to each other and then connecting
them together. i.e.: top and bottom or front and back …etc.
Fig.3.11: Different views of an
Isometric circle.
4.Activities
4.1.Class Work
a) Draw an isometric view of the component shown below to the given
dimensions on the same A3 sheet. All dimensions are in mm.
b) Draw an isometric view of the component shown below to
the given dimensions on A3 sheet. All dimensions are in mm