CHAPTER 1 BLUEPRINTS When you have read and understood this chapter, you should be able to answer the following learning objectives: Describe  blueprints  and  how  they  are  pro- duced. Identify  the  information  contained  in  blue- prints. Explain the proper filing of blueprints. Blueprints (prints) are copies of mechanical or other types of technical drawings. The term blueprint reading, means interpreting ideas expressed by others on drawings, whether or not the drawings are actually blueprints.  Drawing  or  sketching  is  the  universal language used by engineers, technicians, and skilled craftsmen. Drawings need to convey all the necessary information to the person who will make or assemble the  object  in  the  drawing.  Blueprints  show  the construction details of parts, machines, ships, aircraft, buildings, bridges, roads, and so forth. BLUEPRINT PRODUCTION Original drawings are drawn, or traced, directly on translucent tracing paper or cloth, using black water- proof India ink, a pencil, or computer aided drafting (CAD) systems. The original drawing is a tracing or “master copy.” These copies are rarely, if ever, sent to a shop or site. Instead, copies of the tracings are given to persons or offices where needed. Tracings that are properly handled and stored will last indefinitely. The term blueprint is used loosely to describe copies of original drawings or tracings. One of the first processes  developed  to  duplicate  tracings  produced white lines on a blue background; hence the term blueprint.  Today,  however,  other  methods  produce prints of different colors. The colors may be brown, black, gray, or maroon. The differences are in the types of paper and developing processes used. A patented paper identified as BW paper produces prints  with  black  lines  on  a  white  background.  The diazo, or ammonia process, produces prints with either black, blue, or maroon lines on a white background. Another type of duplicating process rarely used to reproduce working drawings is the photostatic process in which a large camera reduces or enlarges a tracing or drawing. The photostat has white lines on a dark background. Businesses use this process to incor- porate reduced-size drawings into reports or records. The  standards  and  procedures  prescribed  for military drawings and blueprints are stated in military standards (MIL-STD) and American National Stan- dards Institute (ANSI) standards. The Department of Defense Index of Specifications and Standards lists these standards; it is issued on 31 July of each year. The  following  list  contains  common  MIL-STD  and ANSI  standards,  listed  by  number  and  title,  that concern  engineering  drawings  and  blueprints. Number MIL-STD-100A ANSI   Y14.5M-1982 MIL-STD-9A ANSI  46.1-1962 MIL-STD-12C MIL-STD-14A ANSI  Y32.2 MIL-STD-15 ANSI  Y32.9 MIL-STD-16C MIL-STD-17B,  Part  1 MIL-STD-17B, Part 2 MIL-STD-18B MIL-STD-21A MIL-STD-22A MIL-STD-25A Title Engineering Drawing Practices Dimensioning and Tolerancing Screw Thread Conventions and Methods of Specifying Surface  Texture Abbreviations for Use on Drawings Architectural Symbols Graphic Symbols for Electrical and Electronic Diagrams Electrical Wiring Part 2, and Equip- ment Symbols for Ships and Plans, Part 2 Electrical Wiring Symbols for Architectural and Electrical Layout Drawings Electrical and Electronic Reference Designations Mechanical Symbols Mechanical Symbols for Aeronautical, Aerospace craft and Spacecraft use Structural Symbols Welded-Joint  Designs,  Armored-Tank Type Welded  Joint  Designs Nomenclature and Symbols for Ship Structure 1-1