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 multi-view orthographic projection.
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Just as aircraft technicians need not be highly skilled in creating drawings, they need not be accomplished artists. However, in many situations, they 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 and dimensioning. [Figures 1 and 2]
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| Figure 1. The meaning of lines |
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| Figure 2. Correct use of lines |
Sketching Techniques
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 3.
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| Figure 3. Steps in sketching |
Basic Shapes
Depending on the complexity of the sketch, basic shapes may be drawn in freehand or by use of templates. If the sketch is quite complicated or the technician is required to make frequent sketches, use of a variety of templates and other drafting tools is highly recommended.
Repair Sketches
A sketch is frequently drawn for repairs or for use in manufacturing a replacement part. Such a sketch must provide all necessary information to those who must make the repair or manufacture the part.
The degree that a sketch is complete depends 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.