Overview
CHAPTER 4
TECHNICAL DRAWINGS
Introduction
In the United States, modern technical drawing can be traced to the year 1849
when a Baltimore, Maryland, schoolteacher published what is widely believed
to be the first text on technical drawing. At that time, technical drawings were
fine line drawings that resembled copperplate engravings. With the
introduction of the blueprint process in 1876, fine line drawings became
obsolete and modern technical drawings evolved. The Industrial Revolution in
the early 1900s further refined, defined, and standardized technical drawing
techniques, nomenclature, and symbology. The term technical drawing
accurately suggests the broad scope of drawings for industry.
Objectives
The material in this chapter enables you to do the following:
Identify the application of freehand drawing techniques in technical
drawings.
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 page
4-1
