196 Section 2 Drafting Techniques and Skills
Construct a
Circle or Arc
of a Given Radius Tangent
to a Straight Line at a Given
Point
CAD
(Manual Procedure)
1. Using a triangle and straightedge, draw
a perpendicular to Line AB at the given
point (Point P), Figure 6-47A.
2. Lay off Radius CP on the perpendicular,
Figure 6-47B.
3. Draw the circle with the center at
Point C using a compass, Figure 6-47C.
The circle is tangent to Line AB at Point P.
An application of this construction to a
drawing problem is shown in Figure 6-47D.
Figure 6-47. Constructing a circle of a given radius tangent to a line at a given point. There are many applications
for this construction in drafting.
A
P
B
P
A
B
C
Application
A B C D
Using the Offset and Circle
Commands (CAD Procedure)
1. Line AB and Point P are given. Refer to
Figure 6-47A.
2. Make a copy of Line AB by offsetting the
line. Enter the
Offset
command
and specify the offset distance as
Radius CP. Refer to Figure 6-47B. Select
Line AB and then pick a point to the
side of the line to offset the line at the
given distance.
3. Enter the
Line
command and draw a
perpendicular line from Point P to the
offset line. Use the Perpendicular object
snap.
4. Enter the
Circle
command and specify
the endpoint of the perpendicular
as the center point. Enter the radius
value. The circle is drawn tangent to
Line AB.