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# Visualization and Sketching

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## 3.10 Isometric Drawings

When you make a drawing using foreshortened measurements, or when the object is actually projected on a plane of projection, it is called an isometric projection (Figure 3.40a). When you make a drawing using the full-length measurements of the actual object, it is an isometric sketch or isometric drawing (Figure 3.40b) to indicate that it lacks foreshortening.

The isometric drawing is about 25% larger than the isometric projection, but the pictorial value is obviously the same in both. Because isometric sketches are quicker (because you can use the actual measurements), they are much more commonly drawn.

#### Positions of the Isometric Axes

The first step in making an isometric drawing is to decide along which axis direction to show the height, width, and depth, respectively. Figure 3.41 shows four different orientations that you might start with to create an isometric drawing of the block shown. Each is an isometric drawing of the same block, but with a different corner facing your view. These are only a few of many possible orientations.

You may orient the axes in any desired position, but the angle between them must remain 120°. In selecting an orientation for the axes, choose the position from which the object is usually viewed, or determine the position that best describes the shape of the object, or better yet, both.

If the object is a long part, it will look best with the long axis oriented horizontally.