Introduction to Freehand Sketching
A freehand sketch is a drawing made without the use of drawing instruments. It is not drawn to scale, but should be in good proportion as accurately as possible by eye judgment. It does not mean that it is a crude and inaccurate drawing without care for the rules of projection. In fact in a freehand sketch, all the rules of the graphic language are as rigidly observed as in a scale drawing. Yes, a fair knowledge of theory of orthographic projection, sections, etc. is a pre-requisite for a good freehand sketching. A freehand sketch should contain all the necessary details such as dimensions and actual shape. It requires a soft pencil preferably of HB grade.
The importance of freehand sketching is often under-estimated. A young person preparing for an engineering career, when beginning his/her studies should understand that freehand sketching will be his/her ultimate form of expression and that he/she must be also to prepare complete sketches to present his/her ideas and decisions to subordinates in an understandable manner.
A proficiency in freehand sketching is an untold asset in the profession. Trainees may find how poor their first attempts are in sketching. The proverb “Practice makes a man perfect” applies very strongly in this case.
Technique of Sketching
(a) Sketching lines. Long lines may be drawn with the forearm motion while short lines drawn with wrist motion. Horizontal lines are drawn from left to right. Vertical lines are drawn from top to bottom with the finger movement in a series of overlapping strokes. Inclined lines running upward from left to right may be sketched upward with the same movement used for horizontal lines.
1. The pencil is held with freedom and not close to the point, say about 30 mm from the tip. The pencil point need not be as sharp as for an instrument drawing.
2. In drawing any straight line between two points keep your eyes on the point to which the line is to go rather than on the point of the pencil.
3. Do not try to draw the whole length of the line in a single stroke.
4. An eraser is permitted, but it is advised to use it sparingly.
(b) Sketching a Circle. The circle which is the most difficult part of freehand sketching, is drawn in stages. In this, first sketch lightly the enclosing square. Mark the mid-points of the sides and draw the centre lines. Now the centre and radius of the circle are obtained. Also draw the diagonals on which mark points for the diameter by eye judgment. Finally draw arcs tangential to the sides & draw a smooth circle passing through the eight points so obtained.
(c) Sketching an Ellipse. First draw the centre lines and then a rectangle with sides equal to the major and minor axes. Draw the portion of the curves at the ends of the major and minor axes and thus complete the ellipse.