Page 24 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

Exercise 2.2
Construct a Parabola given the base and axis of a rectangle; base 80 mm, axis 25 mm - Rectangle method. (Fig 2)
• Draw a rectangle ABCD of sides 80 mm & 25 mm.
• Mark centre points of AD and BC, as E and F, join EF.
• Divide AB & CD and into any number of equal parts say 5. Also divide AE and ED into the same number
of equal parts and number them as shown.
• From point E on AD, draw lines to the divisions on AB & CD.
• From the points on AED, draw parallel lines to EF.
• Mark the intersecting points P , P , P , P on either side of axis.
1 2 3 4
• Form the parabola by joining the points BEC and intersecting with a smooth curve, passing through P , P 2
1
Fig 2

Exercise 2.3

Construct a Parabolic curve with base as 80 mm and axis 30 mm - Tangent method. (Fig 3)
• Draw an isosceles triangle of base 80 mm and altitude 60 mm (double the abscissa).
• Join BD and mark mid point V, the vertex.
• Divide AB and BC into same number of equal parts using divider/other methods.

• Mark the points on AB as 1,2,3 etc in ascending order..
• Similarly mark 1', 2', 3' etc on CB but in descending order.
• Draw lines 1-1', 2-2'..... 7-7'.

• Join the points with A, V and C with a smooth curve. AVC is tangential to line 1 1', 2 2' etc and form the required
parabola.

Fig 3

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CITS :Engineering Drawing (Mechanical) - Exercise 2