Question

Draw the projections of a cone with base 30mm diameter and axis 50mm long resting on HP on a point of its base circle with the axis making an angle 45° with HP and paralla to VP

Answer 1

Answer:

Diameter of cone = $30$ mm

Axis length = $50$ mm

Resting on circular rim on HP

Axis inclination with HP = $45$°

Explanation:

Stage 1

Draw XY line.

Cone is resting on HP, so TV will be a circle and FV will be a triangle.

Draw TV as a circle of diameter $50$ mm.

Draw vertical and horizontal axis of circle.

Divide the circle into $12$ equal parts (You can divide it into 8 parts also). Name all the points $1, 2, 3, 12.$

Take the projections of all point into FV.

Complete the FV taking axis length $60$ mm. Draw all the generators of cone.

Name the FV of cone on base as 1’ 2’ 3’….12’ and O’ as apex.

Stage 2S

As axis is inclined at $30$° to XY line the base line 1’7’ will be inclined at 60° to XY line.

So first mark point 7’ at some convenient distance on XY line. Then draw line 1’ 7’ at angle of $60$°, so that the axis will be inclined at $30$°.

Using compass mark all the points from stage $1$ to stage $2$ on line 1’ 7’.

Complete the FV in inclined position using compass.

Take the vertical projections of all 12 points 1’, 2’, 3’, …12’ and apex points O’ in TV.

Take horizontal projection all points along with apex towards right side from the TV of 1st stage.

Mark the intersection points 1,2,3..12 and apex O.

Draw a smooth curve passing through all the 12 points.

Join end generators with apex.

Stage 3

Now in third stage the top view of an axis is inclined to VP.

Draw a line inclined at angle of $45$° to XY line.

Mark point O at some convenient distance below XY line.

Using compass complete the TV in inclined position

Take the projection all points along with apex into FV.

Take the projection all points along with apex towards right side from the FV of 2nd stage.

Mark intersection points 1’ 2’ 3’, ...12’ and apex O’

Draw a smooth curve passing through all the $12$ points.

Join end generators with apex O.

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