Blueprint Reading And Sketching Including Machine Drawings; Piping Systems; Electrical and Electronics Prints; Architectural and Structural Steel Drawings

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 produced.

Identify the information contained in blueprints.

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 waterproof
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 incorporate
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 Standards
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.