Oblique Projections, Continued
All dimension lines, extension lines, and arrowheads must lie in the planes of
the object to which they apply. Place dimensions outside the object outline
except when it helps to clarify. Align dimensions and notes shown with
leaders to the bottom of the drawing. Notes without leaders should also be
aligned with the bottom of the drawing. There are two systems to indicate
dimensions on drawings; the aligned dimension and the unidirectional
dimension systems. Select one system of dimensioning to use throughout the
drawing. You may show dimensions with either whole numbers and
fractions, decimals, or metric units of measure.
Drawings made with aligned dimensions have
all figures and notes aligned with a dimension line so that all read from the
sides or edges of the drawing. Aligned dimensions are sometimes referred to
as pictorial dimensions.
UNIDIRECTIONAL DIMENSIONS: In the unidirectional dimension system,
all dimension figures and notes are lettered horizontally and are read from the
bottom of the drawing. The unidirectional dimension system is preferred
over the aligned system because it is easier to read and understand.
Figure 6-11 are examples of both the aligned and unidirectional dimensioning