INTRODUCTION TO PRINT READING
DOE-HDBK-1016/1-93
Introduction To Print Reading
Drawing Scale
All drawings can be classified as either drawings with scale or those not drawn to scale.
Drawings without a scale usually are intended to present only functional information about
the component or system. Prints drawn to scale allow the figures to be rendered
accurately and precisely. Scale drawings also allow components and systems that are too
large to be drawn full size to be drawn in a more convenient and easy to read size. The
opposite is also true. A very small component can be scaled up, or enlarged, so that its
details can be seen when drawn on paper.
Scale drawings usually present the information used to fabricate or construct a component
or system. If a drawing is drawn to scale, it can be used to obtain information such as
physical dimensions, tolerances, and materials that allows the fabrication or construction
of the component or system. Every dimension of a component or system does not have
to be stated in writing on the drawing because the user can actually measure the distance
(e.g., the length of a part) from the drawing and divide or multiply by the stated scale to
obtain the correct measurements.
The scale of a drawing is usually presented as a ratio and is read as illustrated in the
following examples.
1" = 1"
Read as 1 inch (on the drawing) equals 1 inch (on the actual
component or system). This can also be stated as FULL SIZE in
the scale block of the drawing. The measured distance on the
drawing is the actual distance or size of the component.
3/8" = 1'
Read as 3/8 inch (on the drawing) equals 1 foot (on the actual
component or system). This is called 3/8 scale. For example, if a
component part measures 6/8 inch on the drawing, the actual
component measures 2 feet.
1/2" = 1'
Read as 1/2 inch (on the drawing) equals 1 foot (on the actual
component or system). This is called 1/2 scale. For example, if a
component part measures 1-1/2 inches on the drawing the actual
component measures 3 feet.
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