210 Section 2 Drafting Techniques and Skills
Chapter Summary
Engineers, architects, designers, and drafters
regularly apply the principles of plane geometry
to solutions of technical problems. Knowledge
of these principles is very important in drawing
geometric constructions accurately. This is true
whether you are using manual drafting tools or
a CAD system.
There are a number of geometric construc-
tions the drafter needs to perform using straight
lines. These include bisecting lines, drawing
perpendicular and parallel lines, and dividing a
line into a number of equal parts.
Angles are also important geometric ele-
ments. The most common techniques for draw-
ing angular constructions include bisecting an
angle, transferring an angle, and laying out a
given angle.
Drafters need to know how to draw poly-
gons. Regular polygons have all sides and
interior angles equal. It is important to know
the techniques for drawing triangles, squares,
pentagons, hexagons, and octagons.
Circular constructions are commonly made
by drafters. Common procedures include draw-
ing a circle using three points, locating the center
of a circle or arc, and constructing a circle within
a square.
Other common geometric construction proce-
dures include drawing tangents to circles andarcs,
connecting parallel lines to circles and arcs, and
laying off the length of a circle circumference.
Review Questions
1. Designers and drafters regularly apply
the principles of _____ to the solutions of
technical problems.
2. The term _____ refers to dividing a line into
two equal lengths.
3. The Midpoint object snap can be used with
the _____ command to bisect an existing
line and locate its midpoint.
4. Using the manual drafting method, you can
draw a line through a point and parallel to
a given line using a triangle and _____.
5. Parallel lines are normally drawn in CAD
with what command?
6. In manual drafting, a line can be drawn
through a point and perpendicular to a
given line using a triangle and T-square or
a(n) _____.
7. Name two manual drafting methods used to
divide a line into a given number of parts.
8. Which CAD command is used to divide a
line into a given number of equal parts?
9. What two CAD commands can be used to
transfer an angle?
10. A _____ is a line or plane drawn at a right
angle to a given line or plane.
11. _____ coordinates are used to draw lines at
a given distance and angle from a specifiedfi
point.
12. Which of the following is not a regular
polygon?
A. Square
B. Pentagon
C. Hexagon
D. Trapezoid
13. What type of triangle has three equal sides
and three equal angles of 60° each?
14. What is the
Polygon
command used for?
15. What type of triangle has two equal sides
and two equal angles?
16. A right triangle has one _____ degree angle.
17. A(n) _____ is a regular polygon with four
equal sides.
18. The _____ option of the
Polygon
command
is used to inscribe a polygon within a circle.
19. In a regular pentagon, each of the interior
angles measures _____.
A. 108°
B. 110°
C. 112°
D. 114°
20. A(n) _____ is a polygon with six sides.
21. Using CAD, a plane fi gure can be trans- fi
ferred to a new location by using the _____
command.
22. In manual drafting, the first step in dupli- fi
cating a plane fi gure with irregular curves
is to _____.