The document discusses various types of engineering drawings including isometric drawings, which show a three-dimensional view of a component or assembly from three surfaces in one view. It also covers orthographic projections, which use front, top, side, and other views to represent a three-dimensional object in two dimensions. The document explains techniques for drawing boxes, more complex shapes, threaded parts, and using section views to show hidden details. It also discusses dimensions, title blocks, line types, and other aspects of creating technical drawings.
4. ISOMETRIC DRAWINGS
A technique called
exploded views is
used to show more
clearly how the parts
of an assembly fit
together.
5. Isometric projection : Drawing a box
1.Draw the front vertical edge of the cube.
2.The sides of the box are drawn at 30
degrees to the horizontal to the required
length.
6. Isometric projection : Drawing a box
3.Draw in the back verticals.
4.Drawn in top view with all lines drawn 30
degrees to the horizontal.
8. Isometric projection : Drawing more
complicated shapes
Draw a guide box.
The box is the size
of the maximum
dimensions. In this
case, 5 long, 3 wide,
and 5 high.
Draw the box in
very lightly.
5
5
3
9. Isometric projection : Drawing more
complicated shapes
Draw a box 4
x 1 x 5, the
shape that
needs to be
removed from
the box to
create the
shape we
require. Draw
the box in
very lightly.
10. Isometric projection : Drawing more
complicated shapes
Now draw in the outline
of the object using a
heavier line.
Using this technique
you can draw complex
shapes accurately
because you can use
the guide box as a
means to measure your
engineering drawing
views.
28. Difference between 1st
and 3rd
angle
Bottom view
Right view Rear viewLeft view
Top view
Front view
Bottom view
Top view
Front view Right viewLeft view Rear view
33. Line types
Visible lines - solid lines that
show visible edges and surfaces.
Hidden lines - short dashes that
show edges and surfaces not
visible in that view.
Centre Lines - alternate long
and short dashes. show the centre
of a circle, a shaft, or other
symmetrical part.
Extension lines - solid lines
that indicate where dimensions
start and end.
Dimension lines - arrows on
either side of a dimension showing
where it starts and ends.
34. Cutting Plane line
Cutting Plane line for short distances
AA
AA
Cutting plane line – can be thick alternately long
and double short dashes or thick medium dashed
lines ending in arrow heads. Used to define
sections for sectional views. Arrow heads indicate
the direction of viewing.
35. Section lines
A A
B
B
Section
AA
Section
BB
Section lines – are thin
lines in a parallel pattern
used to indicate surfaces
in section views resulting
from “cutting.” Section
lines are commonly
referred to as “cross-
hatching.”
37. Sectional views
Sections and sectional views are used to
show hidden detail more clearly
Created by using a cutting plane to cut the
object
A section view shows how the object
would appear if it was cut along the line of
the cutting plane.
38. Sectional views
Sectional views are produced to:
clarify details
show internal features clearly
reduce number of hidden detail lines
aid dimensioning
show cross-section shape
clarify an assembly
When drawn at 30 degrees all lines can be drawn to their true length.
Show how two or more parts of an assembly fit together
Allow you to see where parts are assembled by providing 'centre lines' that you can 'follow' (with your eyes or fingers)
Locate component parts or subassemblies within an assembly
Show how one component part or subassembly is assembled to another
Aid you in visualising what the text of the Process plan says you must do next in the assembly sequence
Show how an assembly could be taken apart, e.g. a repair situation
1st Angle mnemonic The Object comes first, (in front of the paper)
3rd Angle mnemonic The object comes third, (eye, paper, object)
To remember the projection angle rotate the rear of the cone to the right and draw what you see
To remember the projection angle rotate the rear of the cone to the right and draw what you see