Autocad 3d Notes

Lecture Note 09162009 Extrude Command entry: extrude Current wire frame density: ISOLINES=4 Select objects to extrude: Specify height of extrusion or [Direction/Path/Taper angle] <default>: Specify a distance or enter p If you extrude a closed object, the result is a 3D solid. If you extrude an open object, the result is a surface.

You can select the objects to extrude before you start the command. The DELOBJ system variable controls whether the object(s) and path (if selected) are automatically deleted when the solid or surface is created or whether you are prompted to delete the object(s) and path. Object Selection

Specifies the objects to extrude. You can extrude the following objects and subobjects: 

Lines

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Arcs

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Elliptical arcs

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2D polylines

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2D splines

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Circles

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Ellipses

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2D solids

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Traces

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Regions

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Planar 3D polylines

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Planar 3D faces

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Planar surfaces

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Planar faces on solids Note: You can select faces on solids by pressing and holding CTRL, and then selecting these subobjects. You cannot extrude objects contained within a block or polylines that have crossing or selfintersecting segments. If a selected polyline has width, the width is ignored and the polyline is extruded from the center of the polyline path. If a selected object has thickness, the thickness is ignored. Note : You can use CONVTOSOLID to convert polylines and circles with thickness to solids. You can use CONVTOSURFACE to convert lines with thickness; arcs with thickness; and open, zero-width polylines with thickness to surfaces. Height of Extrusion Extrudes objects along the positive Z axis of the object's coordinate system if you enter a positive value. If you enter a negative value, the objects are extruded along the negative Z axis. Objects do not have to be parallel to the same plane. If all the objects are on a common plane, the objects are extruded in the direction of the normal of the plane. By default, planar objects are extruded in the direction of the object’s normal. Specify second point: Specify a point

Direction Specifies the length and direction of the extrusion with two points you specify. Specify start point of direction: Specify a point Specify end point of direction: Specify a point Path

Selects the extrusion path based on a specified object. The path is moved to the centroid of the profile. Then the profile of the selected object is extruded along the chosen path to create solids or surfaces.

Select extrusion path: Use an object selection method The following objects can be paths: 

Lines

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Circles

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Arcs

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Ellipses

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Elliptical arcs

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2D polylines

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3D polylines

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2D splines

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3D splines

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Edges of solids

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Edges of surfaces

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Helixes Note: You can select faces and edges on solids by pressing and holding CTRL, and then selecting these subobjects. The path should not lie on the same plane as the object, nor should the path have areas of high curvature. The extruded solid starts from the plane of the object and maintains its orientation relative to the path. If the path contains segments that are not tangent, the program extrudes the object along each segment and then miters the joint along the plane bisecting the angle formed by the segments. If the path is closed, the object should lie on the miter plane. This allows the start and end sections of the solid to match up. If the object is not on the miter plane, the object is rotated until it is on the miter plane.

Objects with multiple loops are extruded so that all the loops appear on the same plane at the end section of the extruded solid. Taper Angle Specify angle of taper for extrusion <0>: Specify an angle between -90 and +90 degrees, press ENTER, or specify a point If you specify a point for the taper angle rather than enter a value, you must pick a second point. The taper angle applied to the extrusion is the distance between the two specified points. Specify second point: Specify a point

Positive angles taper in from the base object. Negative angles taper out. The default angle, 0, extrudes a 2D object perpendicular to its 2D plane. All selected objects and loops are tapered to the same value. Specifying a large taper angle or a long extrusion height can cause the object or portions of the object to taper to a point before reaching the extrusion height. Individual loops of a region are always extruded to the same height. When an arc is part of a tapered extrusion, the angle of the arc remains constant, and the radius of the arc changes. Planar surface Command entry: planesurf You can create a planar surface by selecting closed objects or by specifying the opposite corners of a rectangular surface. When you specify the corners of the surface through the command, the surface is created parallel to the workplane.

The SURFU and SURFV system variables control the number of lines displayed on the surface.

Specify first corner or [Object]: Specify the first point for the planar surface Specify other corner: Specify second point (other corner) for the planar surface Object Creates a planar or trimmed surface by object selection. You can select one closed object or multiple objects that form a closed area. Similar to the REGION command, valid objects include: line, circle, arc, ellipse, elliptical arc, 2D polyline, planar 3D polyline, and planar spline. The DELOBJ system variable controls whether the object(s) you select are automatically deleted when the surface is created or whether you are prompted to delete the object(s). Select objects: Select one or more objects that define the area for the planar surface Push and pull Command entry: presspull Click inside bounded areas to press or pull. You can press or pull a bounded area by either clicking inside the bounded area or by pressing CTRL + ALT and then clicking the area. As you move the cursor, the area that you want to press or pull changes dynamically and creates a new 3D solid.

You can press or pull any of the following types of bounded areas: 

Any area that can be hatched by picking a point (with zero gap tolerance)

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Areas enclosed by crossing coplanar, linear geometry, including edges and geometry in blocks

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Closed polylines, regions, 3D faces, and 2D solids that consist of coplanar vertices

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Areas created by geometry (including edges on faces) drawn coplanar to any face of a 3D solid

Loft Command entry: loft

The cross sections can be either open or closed 2D objects such as circles, arcs, or splines.

With the LOFT command, you can create a new solid or surface by specifying a series of cross sections. The cross sections define the profile (shape) of the resulting solid or surface. Cross sections (generally, curves or lines) can be open (for example, an arc) or closed (for example, a circle). LOFT draws a solid or surface in the space between the cross sections. You must specify at least two cross sections when you use the LOFT command.

You can use the following objects when creating a lofted solid or surface:

Objects That Can Be

Objects That Can Be

Used as Cross Sections

Used as a Loft Path

Line

Line

Line

Arc

Arc

Arc

Elliptical arc

Elliptical arc

Elliptical arc

2D polyline

Spline

2D spline

2D spline

Helix

3D spline

Objects That Can Be Used as Guides

Circle

Circle

2D polyline Note2D polylines can be used as guides if they contain only 1 segment.

Ellipse

Ellipse

Points (first and last

2D polyline

3D polyline

cross section only) Region

3D polyline

Planar face of solid Planar surface Planar 3D face 2D solid Trace With the Path option, you can select a single path curve to define the shape of the solid or surface. With the Guides option, you can select multiple curves to define the contours of the solid or surface. The DELOBJ system variable controls whether the cross sections, guides, and path are automatically deleted when the solid or surface is created or whether you are prompted to delete these objects. You can select the cross sections before you start the command. Select cross sections in lofting order: Select open or closed curves in the order that the surface or solid will pass through Enter an option [Guides/Path/Cross sections only] : Press ENTER to use the selected cross sections, displaying the Loft Settings dialog box, or enter an option Guides Specifies guide curves that control the shape of the lofted solid or surface. Guide curves are lines or curves that further define the form of the solid or surface by adding additional wireframe information to the object. You can use guide curves to control how points are matched up on corresponding cross sections to prevent undesired results, such as wrinkles

in the resulting solid or surface.

Each guide curve must meet the following criteria to work correctly: 

Intersects each cross section

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Starts on the first cross section

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Ends on the last cross section You can select any number of guide curves for the lofted surface or solid. Select guide curves: Select the guide curves for the lofted solid or surface, and then press ENTER Path Specifies a single path for the lofted solid or surface.

The path curve must intersect all planes of the cross sections. Select path: Specify a single path for the lofted solid or surface

Sweep Command entry: sweep With the SWEEP command, you can create a new solid or surface by sweeping an open or closed planar curve (profile) along an open or closed 2D or 3D path. SWEEP draws a solid or surface in the shape of the specified profile along the specified path. You can sweep more than one object, but they all must lie on the same plane. When you select an object to sweep, it is automatically aligned to the object that is used as the path.

You can use the following objects and paths when creating a swept solid or surface:

Objects that Can Be Swept

Objects that Can Be Used as a Sweep Path

Line

Line

Arc

Arc

Elliptical arc

Elliptical arc

2D polyline

2D polyline

2D spline

2D spline

Circle

Circle

Ellipse

Ellipse

Planar 3D face

3D spline

2D solid

3D polyline

Trace

Helix

Region

Edges of solids or surface

Planar surface Planar faces of solid Note: You can select faces and edges on solids or surfaces by pressing and holding CTRL, and then selecting these subobjects. The DELOBJ system variable controls whether the profile(s) and sweep path are automatically deleted when the solid or surface is created or whether you are prompted to delete the profile(s) and path. You can select the objects to sweep before you start the command. Current wire frame density: ISOLINES=4 Select objects to sweep: Use an object selection method and press ENTER when you finish Select sweep path or [Alignment/Base Point/Scale/Twist]: Select a 2D or 3D sweep path, or enter an option Alignment Specifies whether the profile is aligned to be normal to the tangent direction of the sweep path. By default, the profile is aligned. Align sweep object perpendicular to path before sweep [Yes/No] : Enter no to specify that the profile is not be aligned or press ENTER to specify that the profile is aligned Note: If the profile curve is not perpendicular (normal) to the tangent of the start point of the path curve, then the profile curve automatically aligns. Enter No at the alignment prompt to prevent this. Base Point Specifies a base point for the objects to be swept. If the specified point does not lie on the plane of the selected objects, it is projected onto the plane. Specify base point: Specify a base point for the selection set Scale

Specifies a scale factor for a sweep operation. The scale factor is uniformly applied to the objects that are swept from the start to the end of the sweep path. Enter scale factor or [Reference] <1.0000>: Specify a scale factor, enter r for the reference option, or press ENTER to specify the default value Reference Scales the selected objects based on the length you reference by picking points or entering values. Specify start reference length <1.0000>: Specify a beginning length from which to scale the selected objects Specify end reference length <1.0000>: Specify a final length to which to scale the selected objects Twist Sets a twist angle for the objects being swept. The twist angle specifies the amount of rotation along the entire length of the sweep path. Enter twist angle or allow banking for a non-planar sweep path [Bank] : Specify an angle value less than 360, enter b to turn on banking, or press ENTER to specify the default angle value Select sweep path [Alignment/Base point/Scale/Twist]: Select a sweep path or enter an option Banking specifies whether or not the curve(s) being swept will bank naturally (rotate) along a 3D sweep path (3D polyline, 3D spline, or helix). 2D SOLID Command entry: solid Specify first point: Specify a point (1) Specify second point: Specify a point (2) The first two points define one edge of the polygon. Specify third point: Specify a point (3) diagonally opposite the second Specify fourth point or <exit>: Specify a point (4) or press ENTER

Pressing ENTER at the Fourth Point prompt creates a filled triangle. Specifying a point (5) creates a quadrilateral area. The last two points form the first edge of the next filled area. The Third Point and Fourth Point prompts are repeated. Specifying successive third and fourth points creates further connected triangles and four-sided polygons in a single solid object. Pressing ENTER ends SOLID. 2D solids are filled only when the FILLMODE system variable is on and the viewing direction is orthogonal to the 2D solid.

3D FACE Command entry: 3dface Specify first point or [Invisible]: Specify a point (1) or enter i First Point Defines the start point for the 3D surface. After entering the first point, enter the remaining points in a natural clockwise or counterclockwise order to create a normal 3D face. If you locate all four points on the same plane, a planar face is created that is similar to a region object. When you shade or render the object, planar faces are filled. Invisible Controls which edges of a 3D face are visible, allowing for accurate modeling of objects with holes. Entering i or invisible before the first point of an edge makes the edge invisible. The invisible specification must precede any object snap modes, XYZ filters, or coordinate input for that edge. You can create a 3D face in which all edges are invisible. Such a face is a phantom; it does not appear in wireframe presentations but can hide material in line drawings. 3D faces do appear in shaded renderings. You can combine 3D faces to model complex 3D surfaces.

Specify second point or [Invisible]: Specify a point (2) or enter i Specify third point or [Invisible] <exit>: Specify a point (3), enter i, or pressENTER Specify fourth point or [Invisible] : Specify a point (4), enter i, or press ENTER The Third Point and Fourth Point prompts are repeated until you press ENTER. Specify points 5 and 6 at these repeating prompts. When you finish entering points, press ENTER.

EDGE Command entry: edge Specify edge of 3dface to toggle visibility or [Display]: Select an edge or enter d Edge Controls the visibility of the edges you select. Specify edge of 3d face to toggle visibility or [Display]: The prompt is repeated until you press ENTER.

If the edges of one or more 3D faces are collinear, the program alters the visibility of each collinear edge. Display Selects invisible edges of 3D faces so that you can redisplay them. Enter selection method for display of hidden edges [Select/All] : Enter an option or press ENTER

All Selects the hidden edges of all 3D faces in the drawing and displays them. If you want to make the edges of the 3D faces visible once again, use the Edge option. You must select each edge with your pointing device to display it. AutoSnap™ markers and Snaptips are automatically displayed, indicating the apparent snap locations on each invisible edge. This prompt continues until you press ENTER. Select Selects hidden edges of a partially visible 3D face and displays them. Select objects:

If you want to make the edges of the 3D faces visible once again, use the Edge option. You must select each edge with your pointing device to display it. AutoSnap markers and Snaptips are automatically displayed, indicating the apparent snap locations on each invisible edge. This prompt continues until you press ENTER. 3D MESH Command entry: 3dmesh Enter size of mesh in M direction: Enter a value between 2 and 256 Enter size of mesh in N direction: Enter a value between 2 and 256 Note3DMESH is designed primarily for programmers. Other users should use the 3D command. A polygon mesh is defined by a matrix, the size of which is determined by M and N size values. M times N equals the number of vertices that you must specify.

Specify location for vertex (0, 0): Enter a 2D or 3D coordinate The location of each vertex in the mesh is defined by m and n, the row and column indices of the vertex. Defining vertices begins with vertex (0,0). You must supply the coordinate locations for each vertex in row m before specifying vertices in row m + 1.

Vertices may be any distance from each other. The M and N orientation of a mesh depends on the position of its vertices.

3DMESH polygon meshes are always open in both M and N directions. You can close a mesh with PEDIT.

TABULATED SURFACE Command entry: tabsurf Select object for path curve: The path curve defines the approximated surface of the polygon mesh. It can be a line, arc, circle, ellipse, or 2D or 3D polyline. The mesh is drawn starting at the point on the path curve closest to the selection point. Select object for direction vector: Select a line or open polyline

Only the first and last points on a polyline are considered, and intermediate vertices are ignored. The direction vector indicates the direction and length of the shape to be extruded. The end selected on the polyline or line determines the direction of the extrusion. The original path curve is drawn with wide lines to help you visualize how the direction vector dictates the construction of a tabulated mesh.

TABSURF constructs a 2 by n polygon mesh, where n is determined by the SURFTAB1 system variable. The M direction of the mesh is always 2 and lies along the direction vector. The N direction lies along the path curve. If the path curve is a line, arc, circle, ellipse, or spline-fit polyline, tabulation lines are drawn that divide the path curve into intervals of equal size set by SURFTAB1. If the path curve is a polyline that has not been spline fit, tabulation lines are drawn at the ends of straight segments, and each arc segment is divided into intervals set by SURFTAB1.

EDGE SURFACE Command entry: edgesurf Current wire frame density: SURFTAB1=current SURFTAB2=current

Select object 1 for surface edge: Select object 2 for surface edge: Select object 3 for surface edge: Select object 4 for surface edge: You must select the four adjoining edges that define the mesh patch. The edges can be lines, arcs, splines, or open 2D or 3D polylines. The edges must touch at their endpoints to form a topologically rectangular closed path. You can select the four edges in any order. The first edge (SURFTAB1) determines the M direction of the generated mesh, which extends from the endpoint closest to the selection point to the other end. The two edges that touch the first edge form the N edges (SURFTAB2) of the mesh.