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Exploring Drafting
equilateral triangle. Specifying four sides draws
a square. Regular pentagons, hexagons, and
octagons can also be drawn.
After entering the number of sides, the center
point is specifi ed. The command sequence
includes prompts for the user to inscribe or
circumscribe the polygon. See Figure 7-16. As
you learned in Chapter 6, an inscribed polygon
is drawn within a circle. A circumscribed
polygon is drawn about and is tangent to a
circle. After specifying the orientation of the
polygon, the radius of the circle is entered.
Drawing Hatch Patterns
Hatch patterns are used to fi ll a closed
area with a predefi ned pattern representing
a material or a special graphic symbol. Hatch
patterns are frequently used to represent
materials in section views. Section views are
used to show internal features of an object and
are discussed in Chapter 11. There are different
types of hatch patterns corresponding to
specifi c materials, such as steel, brass, concrete,
and wood. A commonly used hatch pattern
is the general purpose section line symbol,
which consists of continuous lines drawn at
a 45° angle and approximately .125″ apart.
See Figure 7-17. The general purpose section
line symbol is often used when the material
specifi cation is indicated in another location
on the drawing.
axis, and a major axis. See Figure 7-15. The axes
divide the ellipse into four quadrants. Points
for the axis endpoints and center point can be
entered at the keyboard or picked on screen.
Elliptical arcs (portions of an ellipse) can
also be drawn by specifying start and end
angles after locating the axis endpoints. The
start and end angles represent points on the
curve relative to the angular locations of the axis
endpoints. The angles are measured counter-
clockwise from the fi rst axis endpoint, which
is designated as 0°. For example, an arc drawn
with a 0° start angle and 180° end angle
represents half an ellipse.
Drawing Polygons
The Polygon command can be used to draw
regular polygons. First, the number of sides
is entered. Specifying three sides draws an
Minor axis
Minor axis
endpoint
Center point
Major axis
endpoint
Major axis
endpoint
Major axis
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Goodheart-Willcox Publisher
Figure 7-15. An ellipse is drawn by specifying endpoints
for the minor and major axes or by specifying a center
point and the axis endpoints.
Inscribed Polygon
A
Circumscribed Polygon
B
Center point
Center point
Radius
Radius
Goodheart-Willcox Publisher
Figure 7-16. Drawing a polygon. Shown are examples of drawing a hexagon (a six-sided polygon). A—An inscribed
polygon is drawn by specifying the number of sides, a center point, and the radius of the circle within which the
polygon is inscribed. A—A circumscribed polygon is drawn by specifying the number of sides, a center point, and
the radius of the circle about which the polygon is circumscribed.
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