Orthographic projections of solid objects, Front view, top view and left or right side view. Sketching orthographic projections in freehand.

1. FREEHANDSKETCHING
Part II
Prof.T.JEYAPOOVAN
Department of Mechanical Engineering
Hindustan Institute of Technology and Science
Chennai-603103, India
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2. Isometric Sketching Practice
• The idea of a new design is visualized
by designer/engineer and sketched in
isometric/perspective projections.
• Isometric sketching is used for small
objects but perspective sketching is
used for large objects like buildings.
• Isometric sketching can also be
prepared from the orthographic
drawings.
• The three isometric axes are drawn
with two axes at 30° to horizontal and
another axis vertical as shown in
figure.
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3. Sketching a circle in isometric
• Draw two isometric axes approx. at
30º to the horizontal.
• Construct the rhombus with the
sides approximately equal to the
diameter of the circle.
• Sketch lines through the midpoints
of the opposite sides of rhombus.
• Sketch short arcs tangent to the
sides of the rhombus.
• Sketch the ellipse by connecting the
arcs in thin light lines and complete
the ellipse by drawing dark lines.
• Ellipses drawn in left and right
isometric planes are shown in Fig.
Top Plane
Left Plane Right Plane
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4. Sketching fromPictorial view from
Orthographic views
• Beginners to the isometric sketching practice can use the
ruled papers with isometric lines. These lines are used as
guidelines for the isometric sketching.
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5. Sketching Isometric Drawing from
Orthographic views
• Sketch the rectangular box in isometric with proportional
dimensions after carefully observing shape and size of the object.
• Sketch the given orthographic views on the top, left and right
planes in thin light lines.
• Complete the isometric drawing by sketching the visible edges of
the object in dark lines.
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6. Sketching Isometric Drawing from
Orthographic views
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7. Sketching Isometric Drawing from
Orthographic views
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8. Tips to draw Freehand sketching
• The visible and invisible edges are usually identified
through visualization and understanding.
• Note that the dimensions of the lines sketched in the
views are taken in proportion to the dimensions of the
object.
• Sketches are not prepared to scale/actual dimensions.
• The rectangle to enclose the views can be omitted after
practicing many sketching exercises with an eye on
taking the proportional dimensions of the object.
• Complete the sketching of the object by drawing dark
lines.
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9. www.jeyapoovan.com
REFERENCE BOOKS
1. Jeyapoovan T, “Lesson Plans for Engineering
Graphics”, 2010, Vikas Publishing House Pvt
Ltd, New Delhi.
2. Jeyapoovan T, “Engineering Drawing and
Graphics”, 2011, Vikas Publishing House Pvt
Ltd, New Delhi.

10. End of Lesson 15
ThankYou
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