This document provides 14 steps to draw the isometric projection of a frustum of a cone with given dimensions. Key steps include: 1) Drawing the top and front views of the solid with true dimensions and marking the dimensions. 2) Using a conversion factor of 0.816 to plot points and lines onto the isometric axes from the top and front views. 3) Drawing the base and top circles as ellipses within boxes representing their true circular shapes. 4) Joining the top and bottom ellipses tangentially to complete the isometric projection of the frustum of a cone.

1. Isometric Projection of
Frustum of a Cone
Drawing Steps By:
SUBIN B MAROSE
Assistant Professor
Department of Mechanical Engineering
PH: 9048572058

2. Question
• Draw the isometric projection of a frustum of
cone with base diameter 60 mm, top base diameter
35mm and axis length 50 mm.

3. Step 1
• Draw the top and front view of the solid in true
dimensions.

5. Step 2
• Mark the dimensions.
• Enclose the bottom circle inside a box and name it
1-2-3-4.
• Similarly enclose top circle in box 5-6-7-8.

7. Step 3
• Draw the isometric axes and plot point 1.

9. Step 4
•Important to take conversion factor=
0.816 since it is isometric projection.
• Note the length 1-2 which is 60 mm and plot its iso
length = 60 * 0.816 = 48.9 mm onto the isometric
axes.

11. Step 5
• Complete the box 1-2-3-4 in iso length.

13. Step 6
• Base circle will be represented as an ellipse which
we have drawn in several questions before.
• In this question, steps of drawing ellipse are not
repeated but it is visually represented.
• Any doubt, refer previous questions.

18. Step 7
• Draw a vertical line of height = iso height of
Frustum = 50 * 0.816 = 40.8 mm at point 2.

20. Step 8
• Similarly draw similar vertical lines from other
edges of the box.
• Join the end points of the lines.
• Name the top box also as 1-2-3-4 to avoid
confusion.

24. Step 9
• Now focus on top view.
• From point 6, draw a horizontal line and name the
meeting point as 'm'.
• From point 6, draw a vertical line and name the
meeting point as 'n'.

26. Step 10
• Lengths of 6-m and 6-n are equal here = 13 mm
• Plot the iso length of 6-m and 6-n = 13 * 0.816 =
10.6 mm onto edges 2-3 and 1- 2 respectively.

28. Step 11
• Draw parallel lines from points 'n' and 'm' as shown
in next slides.

31. Step 12
• You can complete the top box as shown in next
slide by taking similar dimensions.
• Name the box 5-6-7-8 which now you have created
and it is the isometric projection of the box 5-6-7-8
we have drawn in top view.

33. Step 13
• Since top of Frustum is also a circle, it will be seen
as an ellipse in the isometric projection.
• So we have to draw an ellipse in the box 5--6-78.
• Repeat all the steps we followed for drawing the
base ellipse.
• Refer the coming slides.

40. Step 14
• Join the top and bottom ellipse as shown
tangentially.
• Highlight the figure as shown.
• Please make sure that you darken the lines only at
the end.

43. Comments
• It is Isometric Projection.
• So take conversion factor.
• Draw lightly.
• Darken the figure only at the end.
• Practice and learn.
• Please feel free to rectify the doubts.

44. • End of presentation...