Basic Technology, JSS 1, Week: 4

Topic: Freehand Sketching

When we see a photograph of an object, we understand immediately its message. If we are thinking of an imaginary object, we cannot take its photograph immediately as we can only imagine it. What can be done is to sketch the imaginary picture of the object. So freehand sketching is of advantage because a good sketch reduces the amount of writing needed to describe an object.

A simple sketch of an object, a building or a machine will suggest the intention of the designer to the builder or the consumer better than lengthy description of the same design. Therefore we can say that freehand sketching is one of the quickest methods by which the shape of an object can be communicated to others without using any drawing instrument except a pen or a pencil. The ability to make freehand sketches is a valuable  asset acquired through practice. A student will find that sketching makes him observant and accurate.

Sketching a Straight Line

A straight line is defined as the shortest distance between two points. We can use freehand to draw a fairly straight line by the following procedures:

  1. Put a dash or dot far enough to the right hand side of the paper.
  2. Start to draw a line from the left hand side to join the dash or dot with your eyes fixed on the point.

Sketching a Curve

To draw a curve by freehand, it will be necessary to plot some points not too far from each other at different levels.

With the points in position, attempt to draw curves and join them.

Sketching a Circle

To draw circles, the easiest way is to draw lines which are equal in diameter to the circle in different directions.  Each line must be drawn as faint and straight as possible, each crossing one another at a central point.

Then, join the points by little curves from the tip of each line. Try to draw other circles by means of joining two large curves having half the size as radius and full size in diameter.

Sketching a Square Box

This can be sketched in an isometric or oblique view. Isometric views have the vertical heights and the baselines inclined at 300 to the horizontal. Oblique views have the height vertical and one baseline inclined at 450 to the horizontal while the second baseline is horizontal. Once it is decided which view to represent, the block is drawn by using a series of straight lines both vertical and horizontal, applying the techniques discussed earlier.

Picture-14

                                                              An Isometric square block  

 


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                                                                An Oblique Image

Sketching an Irregular Edge

Figures with irregular edges are best drawn by first sketching a rectangular or square block which can completely contain the object. The shape is then carefully shaped by using dotted lines joined to show the desired shape with appropriate curves.