us think of a sketch as a freehand drawing, which is not always the case. You may sketch on graph paper to take advantage of the lined squares, or you may sketch on plain paper with or without the help of drawing instruments. Technical sketches are drawn without mechanical aid, like a t-square, compass, or straight edge, but, like other forms of architectural drafting, are drawn to scale and contain a variety of line weights and line styles (Figure 1). The pencil or pen is guided by the hand of the drafter alone and this is usually done on trace paper over a 1/4" grid paper. The grid paper becomes the guide helping to keep lines straight.
A technical sketch gives an idea that the design is still being developed while a mechanically drafted or CAD drawing implies an advanced state of planning and gives the impression the design has been finalized.
Figure 1. Examples of technical sketch showing ideas and scale of design
Mechanical drafting is a refined style of drawing in which the pencil or pen is guided by devices such as t-squares, parallel rules, straightedges, compasses, triangles, and French curves (Figure 2). These drawings are developed only after the conceptual phase of a project has been completed and the design is finalized. However, it is typical to see revisions of construction documents as well as