OverviewCHAPTER 4TECHNICAL DRAWINGSIntroductionIn the United States, modern technical drawing can be traced to the year 1849when a Baltimore, Maryland, schoolteacher published what is widely believedto be the first text on technical drawing. At that time, technical drawings werefine line drawings that resembled copperplate engravings. With theintroduction of the blueprint process in 1876, fine line drawings becameobsolete and modern technical drawings evolved. The Industrial Revolution inthe early 1900s further refined, defined, and standardized technical drawingtechniques, nomenclature, and symbology. The term technical drawingaccurately suggests the broad scope of drawings for industry.ObjectivesThe material in this chapter enables you to do the following:Identify the application of freehand drawing techniques in technicaldrawings.Describe freehand technical sketching techniques.Differentiate between technical sketching and technical drawings.Understand the importance of proportion and accuracy in technical drawing.Recognize graphic symbols for electrical and mechanical drawings.Recognize graphic symbols for structural drawings.Identify machine drawing screw thread technology.Interpret piping blueprints.Continued on next page4-1
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