Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

514 Chapter 16 Engineering Drawings and Symbols

Engineered products generally consist of many parts. In today’s globally driven economy,

some of the parts made for a product in one place must be easily assembled with parts made

elsewhere. When you specify a dimension on a drawing — say, 2.50 centimeter — how close

does the actual dimension of the machined part need to be to the specified 2.50 cm for the part

to fit properly with other parts in the product? Would everything fit correctly if the actual

dimension of the machine part were 2.49 cm or 2.51 cm? If so, then you must specify a toler-

ance of 0.01 cm on your drawing regarding this dimension. Tolerancing is a broad subject

with its own rules and symbols, and as we mentioned earlier, the American National Standard

Institute sets the tolerancing standards that must be followed by those creating or reading

engineering drawings. Here, we have briefly introduced these ideas; you must consult the stan-

dards if you are planning to prepare an actual engineering drawing.

Example 16.2 Show the dimensions of the object in Figure 16.8 on its orthographic views.

1 

1.5

4 

1 

1 

0.5

0.5

0.5

1 

0.5

0.5

0.5

1 

0.5

f 0.5

f 0.5

1.5 1.5

1 

0.5

0.5

1.5

0.5 0.5

0.5

0.5

4  0.5

1.5

■Figure 16.8 An object and its dimensions.

16.4 Isometric View

When it is difficult to visualize an object using only its orthographic views, an isometric sketch

is also drawn. Theisometric drawingshows the three dimensions of an object in a single view.

The isometric drawings are sometimes referred to as technical illustrations and are used to show

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