A sketch is a simple, rough drawing that is made rapidly and without much detail. Sketches may take many forms - from a simple pictorial presentation to a multiview orthographic projection.

A sketch is frequently drawn for use in manufacturing a replacement part. Such a sketch must provide all necessary information to those persons who must manufacture the part.

A mechanic need not be an accomplished artist. However, in many situations, he will need to prepare a drawing to present an idea for a new design, a modification, or a repair method. The medium of sketching is an excellent way of accomplishing this.

The rules and conventional practices for making mechanical drawings are followed to the extent that all views needed to portray an object accurately are shown in their proper relationship. It is also necessary to observe the rules for correct line use (figure 2-15 and figure 2-16) and dimensioning.
To make a sketch, first determine what views are necessary to portray the object; then block in the views, using light construction lines. Next, complete the details, darken the object outline, and sketch extension and dimension lines. Complete the drawing by adding notes, dimensions, title, date and, when necessary, the sketcher's name. The steps in making a sketch of an object are illustrated in figure 2-21.

The degree to which a sketch is complete will depend on its intended use. Obviously, a sketch used only to represent an object pictorially need not be dimensioned. If a part is to be manufactured from the sketch, it should show all the necessary construction details.