2004

Table Of Contents
Modify 3D Solids | 433
Boundary sets are sets of faces defined by a closed boundary, which consists of
lines, circles, arcs, elliptical arcs, and spline curves. When defining a
boundary set on a solid object, you first select an internal point on the solid,
highlighting the face. If you select the same point on the face again,
AutoCAD highlights the adjoining face.
You can also select individual faces or edges with your pointing device or use
a crossing window, an irregular shaped polygon, or a fence that selects faces
or edges it passes through.
Extrude Faces on 3D Solids
You can extrude planar faces along a path, or you can specify a height value
and a tapered angle. Each face has a positive side, which is the side in the
direction of the face’s normal (the current face you’re working on). Entering
a positive value extrudes the face in its positive direction (usually outward);
a negative value extrudes in the negative direction (usually inward).
Tapering the selected face with a positive angle tapers the face inward, and a
negative angle tapers the face outward. The default angle, 0, extrudes the face
perpendicular to its plane. If you specify a large taper angle or a long extru-
sion height, you can cause the face to taper to a point before it reaches the
extrusion height; AutoCAD rejects the extrusion. Face extrusion along a path
is based on a path curve (lines, circles, arcs, ellipses, elliptical arcs, polylines,
or splines).
You can also extrude the face of a solid object along the path of a specified
line or curve. All profiles of the selected face extrude along the chosen path
to create the extrusion. You can select lines, circles, arcs, ellipses, elliptical
arcs, polylines, or splines as paths. The path should not lie on the same plane
as the selected face or have areas of high curvature.
To extrude a face on a solid object
1 From the Modify menu, choose Solids Editing Extrude Faces.
2 Select the face to extrude (1).
3 Select additional faces or press
ENTER to extrude.
4 Specify the height of extrusion.