Copyright Goodheart-Willcox Co., Inc.
204
AutoCAD and Its Applications—Advanced
Hole
A B C
Counterbore
Figure 8-30.
Constructing a
counterbore. A—
Draw a cylinder to
represent a hole.
B—Draw a second
cylinder to represent
the counterbore.
C—Subtract the two
cylinders from the
base object.
the
3points
option. Pick three points on the cutting plane and then select the side of
the object to keep.
Exercise 8-10
www.g-wlearning.com/CAD/
Complete the exercise on the companion website.
Removing Features Removing Features
Sometimes, it may be necessary to remove a feature that has been constructed. For
example, suppose you placed a R.5 fi llet on an object based on an engineering sketch.
Then, the design is changed to a R.25 fi llet. Subobject editing is the best technique to
accomplish this. Subobject editing is covered in Chapter 11.
Constructing Features on Constructing Features on
Solid Models Solid Models
A variety of machining, structural, and architectural features can be created using
some basic solid modeling techniques. The features discussed in the next sections are
just a few of the possibilities.
Counterbore and Spotface
A counterbore is a recess machined into a part, centered on a hole, that allows the
head of a fastener to rest below the surface. Create a counterbore as follows.
1. Draw a cylinder representing the diameter of the hole, Figure 8-30A.
2. Draw a second cylinder that is the diameter of the counterbore and center it at the
top of the first cylinder. Move the second cylinder so it extends below the surface
of the object to the depth of the counterbore, Figure 8-30B.
3. Subtract the two cylinders from the base object, Figure 8-30C.
A spotface is similar to a counterbore, but is not as deep. See Figure 8-31. It provides
a fl at surface for full contact of a washer or underside of a bolt head. Construct it in the
same way as a counterbore.