Lesson 15-freehand-sketching-ii


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Lesson 15-freehand-sketching-ii

  1. 1. FREEHAND SKETCHING Part II Prof.T.JEYAPOOVAN Department of Mechanical Engineering Hindustan Institute of Technology and Science Chennai-603103, India www.EGlive.in
  2. 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. www.EGlive.in
  3. 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. www.EGlive.in Top Plane Left Plane Right Plane
  4. 4. Sketching from Pictorial 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. www.EGlive.in
  5. 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. www.EGlive.in
  6. 6. Sketching Isometric Drawing from Orthographic views www.EGlive.in
  7. 7. Sketching Isometric Drawing from Orthographic views www.EGlive.in
  8. 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. www.EGlive.in
  9. 9. 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. www.EGlive.in
  10. 10. End of Lesson 15 Thank You www.EGlive.in