FREEHAND SKETCHING
A freehand sketch is a drawing in which all the proportions and measurements are
judged by the eye and all the lines are drawn without the use of drawing instruments: the only tools used are pencil, eraser and paper. If drawing of an existing building is to be made, it will not be possible to carry all the drawing instruments at the site and to make the formal drawings there. Instead the engineer will make a sketch in his note-book after taking the measurements, then, later on, at a favorable time sitting in his office, he may carry out the detailed drawing work. Further an engineer usually draws sketches only and it is the job of draftsmen to carry out the drawing work Sketches should be made such that they are easily readable by the same person and by the others.
Following points may be kept in mind while making sketches:
1. All the dimensions should be in some proportions that means bigger dimensions should actually be bigger than the smaller ones. If a pictorial view is provided, it may be enclosed in a rectangle and divisions of a suitable length may be marked on it to judge the proportions. If the object is bigger one like a building, the proportions may be
Fig. 3.16 Guessing Proportions of Bigger Objects
estimated by the procedure illustrated in Fig. 3.17. A pencil is held in the fully stretched
right hand. End of the pencil is coincided with the start of the dimension to be estimated and the dimension is marked on the pencil with the tip of the thumbnail. Depending upon size of the paper this dimension may be enlarged or reduced. The other dimensions may be estimated in the same way which must also be enlarged or reduced by the same factor. This method enables the working person to maintain the ratio between all the dimensions.
2. Straight lines should be as straight as possib1e multi stroke lines are generally used
for the bigger lengths.
3. To draw a circle,, first sketch the center-lines, then draw the 45 construction lines as
shown in Fig. 3.18. By guess, mark a distance equal to radius on all these lines and
join by a smooth curve.
Fig. 3.17 To Draw Freehand Circle
