Chapter 8 Creating and Working with Solid Model Features
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Countersink
A countersinkis like a counterbore with angled sides. The sides allow a flat-headmachine k fl
screw or wood screw to sit fl ush with the surface of an object. A countersink can be drawn in fl fl
one of two ways. You can draw an inverted cone centered on a hole and subtract it from the
base or you can chamfer the top edge of a hole. Chamfering is the quickest method.
1. Draw a cylinder representing the diameter of the hole, Figure 8-31A.
2. Subtract the cylinder from the base object.
3. Select the
CHAMFER
or
CHAMFEREDGE
command.
4. Select the top edge of the base object.
5. Enter the chamfer distance(s).
6. Pick the top edge of the hole, Figure 8-31B.
Boss
A boss serves the same function as a spotface. However, it is an area raised above
the surface of an object. Draw a boss as follows.
1. Draw a cylinder representing the diameter of the hole. Extend it above the base
object higher than the boss is to be, Figure 8-32A.
2. Draw a second cylinder the diameter of the boss. Place the base of this cylinder
above the top surface of the base object a distance equal to the height of the boss.
Give the cylinder a negative height value so that it extends inside of the base object,
Figure 8-32B.
3. Union the base object and the second cylinder (boss). Subtract the hole from the
unioned object, Figure 8-32C.
4. Fillet the intersection of the boss with the base object, Figure 8-32D.
Figure 8-31.
Constructing a countersink. A—Subtract the cylinder from the base to create the hole. B—
Chamfer the top of the hole to create a countersink.
Edge to
chamfer
A B
Figure 8-32.
Constructing a boss. A—Draw a cylinder for the hole so it extends above the surface of the
object. B—Draw a cylinder the height of the boss on the top surface of the object. C—Union
the large cylinder to the base. Then, subtract the small cylinder (hole) from the unioned
objects. D—Fillet the edge to form the boss.
A B C D