Department
of
Technological
Education
Graphic Communication
Cut Cones
Cut Cones
At the end of this unit you will be able to:
•Identify a Cone and draw orthographic
views of Cones with cut surfaces.
•Project a cut surface on a Cone
between the Elevation, Plan and
End Elevation.
•Construct a Surface Development of
a Cone.
•Draw the True Shape of a cut surface on a Cone.
Department of Technological Education
Cut cone
The given views
show the Front
Elevation and part
Plan of a cut cone.
Draw the following
views :Complete Plan
End Elevation
Development
True Shape of cut
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Finding position of End Elevation
Start drawing the End
Elevation by
projecting the height
and width from the
given views.
Department of Technological Education
Drawing Generators on Plan
Use 30o and 60o lines
to divide the Plan into
12 equal parts.
Number each of the
points on the Plan.
12
11
1
10
2
9
3
8
4
7
6
5
Department of Technological Education
Transfer Generators from Plan to Elevation
Project each of the
points from the Plan
onto the Elevation
base.
12
11
1
10
2
9
Number each of the
points on the
Elevation making sure
that the numbers
correspond with
those on the Plan.
3
8
4
7
910 11
8 7
6
12
6
5
1
5
23
4
Department of Technological Education
Drawing generator on Elevation
Draw generators from
the apex of the cone
to each of the points
1
0
found on the base of
the cone.
9
1
1
1
2
1
2
3
8
4
7
910 11
8 7
6
12
6
5
1
5
23
4
Department of Technological Education
Drawing generators onto End Elevation
Project the position of
the generators onto
the End Elevation by
10
projecting the points
from the Plan.
9
Number each of the
points on the End
Elevation.
12
11
1
1
2
3
8
4
7
6
5
Draw generators from
the apex to the base.
910 11
8 7
12
6
1
5
23
4
67
5
8
4
9
3
10 1112
2 1
Department of Technological Education
Finding cut points on End Elevation
Project the points
where the generators
on the Elevation cross
10
the cut onto the End
Elevation.
9
Mark each of the
points found with a
small dot.
12
11
1
2
3
8
4
7
910 11
8 7
6
12
6
5
1
5
23
4
67
5
8
4
9
3
10 1112
2 1
Department of Technological Education
Completing End Elevation
Complete the End
Elevation by drawing
a smooth curve
through each of the
point and then
darkening the other
outlines on the view.
1
1
1
2
1
1
0
2
9
3
8
4
7
910 11
8 7
6
12
6
5
1
5
23
4
67
5
8
4
9
3
10 1112
2 1
Department of Technological Education
Finding cut points on Plan
Project the points
from the cut on the
Elevation up to the
correct generator
lines on the Plan.
1
1
1
2
1
1
0
2
9
(Note that points 6
and 12 will not be
able to be found at
this time.)
3
8
4
7
6
5
Mark each of the
points found with a
small dot
910 11
8 7
12
6
1
5
23
4
67
5
8
4
9
3
10 1112
2 1
Department of Technological Education
Finding points 6 and 12 on Plan (alternative 1)
Project point 6 and 12
onto the outside
generator on the
Elevation.
1
1
1
2
1
1
0
2
9
Project this point
up to the centre line
of the Plan.
3
8
4
7
Use compasses to
rotate this point
onto the correct
generators for points
6 and 12.
Mark each of these
points with a small
dot
6
1
01
1 1
2
9
8 7
6
5
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
Department of Technological Education
Finding points 6 and 12 on Plan (alternative 2)
Project points 6 and
12 from the End
Elevation onto the
correct generators on1
0
the Plan.
1
1
1
2
1
2
9
3
8
4
7
6
1
01
1 1
2
9
8 7
6
5
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
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Completing Plan
To complete the Plan
draw a smooth curve
through each of the
12 points found.
1
0
1
1
1
2
1
2
9
3
8
4
7
6
1
01
1 1
2
9
8 7
6
5
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
Department of Technological Education
Development of surface (1)
Mark the position where
the apex of the
Development will be
placed.
Draw the first
generator.
Draw the base line of
the Development.
1
1
1
2
1
1
0
10
9
3
8
Step off the size to each
generator point along the
base.
9
2
11
4
7
6
12
5
1
2
Number each of the
points found.
3
4
Draw generator lines
from the apex to each
of the points on the
base.
5
6
1
01
1 1
2
9
8 7
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7
Department of Technological Education
Development of surface (2)
It is necessary to
find the ‘true length’
of the cut points
along each
generator.
1
1
1
2
1
1
0
1
0
9
To find these sizes
project a line
through each point
on the cut of the
Elevation to the
outside generator.
9
2
3
8
1
1
4
7
6
1
2
5
1
2
3
Mark each of the
found points with a
small dot.
4
5
6
1
01
1 1
2
9
8 7
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7
Department of Technological Education
If the development of the outer surface was to be made from sheet metal then
it would have been developed starting with the shortest edges to the outside.
The reason is that less work and materials would be required for the joins
Development of surface (3)
Measure the distance
from the apex to each
point on the outside
generator.
1
1
1
2
1
1
0
Transfer this size to
9
the correct generator on
the Development.
1
0
3
8
1
1
4
7
Mark each point with
a small dot.
9
2
6
1
2
5
1
2
Draw a smooth curve
through each point
found.
3
4
Darken each of the other
outlines on the
Development.
1
01
1 1
2
9
8 7
6
5
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7
Department of Technological Education
True Shape of cut (1)
Project each of the
points on the cut of
the Elevation away at
right angles to the cut1
0
surface.
1
1
1
2
1
1
0
9
Draw a datum line
on the True Shape
– in this case the
centre line has been
chosen.
9
2
3
8
1
1
4
7
6
1
2
5
1
2
Number each of the
lines projected up to
the True Shape.
3
4
5
6
1
01
1 1
2
9
8 7
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7
Department of Technological Education
True Shape of cut (2)
Measure the sizes
from the cut points to
the centre line on the
Plan and transfer each
0
of these sizes to the 1
correct lines on the 9
True Shape.
1
1
1
2
1
1
0
3
8
Note – These sizes
can also be measured
from the End
Elevation.
9
2
1
1
4
7
6
1
2
5
1
2
3
Mark each of the
points with a small
dot.
4
5
6
1
01
1 1
2
9
8 7
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7
Department of Technological Education
True Shape of cut (3)
To finish the True
Shape draw a smooth
curve through each of
1
0
the points found.
The final drawing
should look like
this.
1
1
1
2
1
9
2
1
0
9
3
8
1
1
4
7
6
1
2
5
1
2
3
4
5
6
1
01
1 1
2
9
8 7
6
1 23
5 4
6
8
4
9
3
1
01
1
1
2
2 1
9
8
7