1. FREEHAND SKETCHING Part I Prof.T.JEYAPOOVAN Department of Mechanical Engineering Hindustan Institute of Technology and Science Chennai-603103, India www.EGlive.in

2. Freehand Sketching An engineer or designer conceives an idea of a non-existing object three dimensionally, which can be conveyed to another person only through a drawing. Initially the object is sketched on paper as an isometric or perspective drawing, then that will be given dimensions. Good practice in freehand sketching helps the engineer to think about the new design rather than to think about the method of preparing the drawing. When the designer’s mind thinks an idea that is sketched by him in freehand. An engineer who has a thorough idea in isometric and orthographic projections can prepare the sketches easily. www.EGlive.in

3. Freehand Sketching Practice For freehand sketching practice, soft grade pencil (HB), eraser and paper are required. Papers with thin cross-section guidelines (ruled paper) may be used for sketching which helps the inexperienced person to draw straight lines satisfactorily. www.EGlive.in

4. Sketching a straight line Mark the end points of the line to be sketched. Observe the two points carefully and make some trial movements between the points without sketching any line. Sketch light and thin trial lines connecting the two points. Complete the straight line by drawing a straight and dark line over the thin line. www.EGlive.in

5. Sketching a small circle Sketch the center lines for the circle horizontally and vertically and mark four points on them approximately equal to the radius of the circle. Sketch the light circle passing through these points. Complete the circle with dark lines. www.EGlive.in

6. Sketching a big circle Sketch the center lines for the circle horizontally and vertically and mark four points on them approximately equal to the radius of the circle. Sketch more diagonal lines in addition to the center lines for big circle. Sketch the light circle passing through these points. Complete the circle with dark lines. www.EGlive.in

7. Sketching Orthographic views from pictorial view Observe the shape of the object carefully. Sketch thin and light rectangles for the views to be drawn. Sketch and complete the views, then darken the lines. www.EGlive.in

8. Sketching Orthographic views from pictorial view Observe the shape of the object carefully. Sketch thin and light rectangles for the views to be drawn. Sketch and complete the views, then darken the lines. www.EGlive.in

9. Sketching Orthographic views from pictorial view Observe the shape of the object carefully. Sketch thin and light rectangles for the views to be drawn. Sketch and complete the views, then darken the lines. www.EGlive.in

10. Sketching Orthographic views from pictorial view Observe the shape of the object carefully. Sketch thin and light rectangles for the views to be drawn. Sketch and complete the views, then darken the lines. www.EGlive.in

11. 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

12. 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.

13. End of Lesson 14 Thank You www.EGlive.in