Monday

AutoCAD 2007, Command

Commands retired with AutoCAD 2007

I will be talking about the commands that have now retired with the AutoCAD 2007 release. You can still make use of them, but they neither appear in the toolbars or the menus, they can only be accessed from the command prompt.

Note: I won’t mention the group command that has long been retired.

CHANGE:
Command: change
Shortcut: -ch (with the hyphen)

The change command has been AutoCAD’s property editing tool for a long time. It’s been there right from the earli est versions. Although no one takes it seriously nowadays, you should know that in the earlier versions, there was no other way for changing properties. Change command can modify both the primary properties and the coordinates of the object.

Fig.1 Changing end points of lines using the old Change command.

Change Point: This feature moves a point of the object nearest to the cursor while you were selecting the object, to another point that you specify. You can edit Line, Circle, Text, Attribute Definition and Block objects using this feature. Select only objects of the same kind, as the software might get confused. When applied on a line, it gives the same result as if the Line had been modified using Stretch. When applied on circles, you will notice that the diameter also changes. If ORTHO mode (F8) is on while selecting a point, the endpoint of your line will not go to the point that you specify but will move only in X or Y axis.

Properties: You can adjust the Color, Elevation, Linetype, Layer, Line Type Scale, Line Weight, and Thickness along Z-axis. You can change more than one property of an object in a row. If you select objects with different properties, you will see “varies” as the property value.

3Dxxx:

This command can be used to draw three dimensional primitive geometries, called Mesh objects. You can call these objects either from the right-click menu of the 3D command or from the command prompt. They have the advantage of file-size over solids, as meshes use up less memory. You can choose these objects if you will not be making any “solid editing” operations on them. Materials can be applied on them, and through the use of grip points, theu can easily be edited.

Fig.2 The retired ones.

Box (ai_box): Creates a 3D rectangular prism. Just specify lenght, width, height, and the angle of rotation. When asked for width, you can create a cube with the “cube” option.

Cone (ai_cone): They are generally seperated as sharp edged cones and frustum cones. Both with cylinders and cones, the main properties are circular base, top face and the height. You can specify the sizes of the base and the top as either raduis or diameter. Cones help you to define three basic shapes depending on the value of the top radius;

• For a usual cone with a pointed top, 0
• A value different than the raduis for the base for a frustum cone
• The same value as the base radius to obtain a cylinder

Dish (ai_dish): Used to draw a bowl or inverted dome. You specify the radius or the diameter, and then the number of longitudinal and latitdunial segments. These numbers determine how accurate the curvature will appear.

Dome (ai_dome): Used to draw dome. You specify the radius or the diameter, and then the number of longitudinal and latitdunial segments. These numbers determine how accurate the curvature will appear.

Mesh (ai_mesh): Used for drawing a two dimensional mesh. Just like a net. The net consists of a number of flat polygonal surfaces. Firstly you specify the end points of the mesh or you can either specify the vertex points one by one or type in the coordinates. You will see that a flat surface appears once you specify the vertex points. Then you will be asked to determine the density of the net along its width and length.

Pyramid (ai_pyramid): Use this to draw a pyramid with a quadrilateral base (5 faces) or with a triangular base (4 faces). The important properties are the base and the height. If you select Ridge when prompted to specify the apex point, you will have to specify the beginning and ending points of the ridge line. With this feature, you will have a pyramid that has triangular sides on an opposing pair of faces, while the other sides are quadrilaterals. It will end up looking like a roof. In the same step, if you select Top (when prompted for Apex..) you will have to specify all the top points, First, Second, Third and the Fourth top points in order to draw a frustum pyramid (or a pyramid with the top cut off..). You cannot use the ridge feature with tetrahedrons, but you can define a top surface for a frustum pyramid or define an apex point. Don’t select the apex points by clicking with the mouse at an approximate place. Use either cartesian coordinates or snap on to another predrawn object.

Sphere (ai_sphere): Draws a sphere about a given center point. The sphere consists of many little flat surfaces arranged to appear like a sphere. You have to specify the center/starting point and then the radius(or the diameter) and then the resolution along the lattitudes and the longitudes (Number of Longitudinal Segments, Number of Latitudinal Segments).

Torus (ai_torus): A torus is like a 3D ring or a real donut. This command is used to draw a torus. It consists of a cylindrical tube bent around a circular path. Try to keep the diameter of the tube less than that of the circular path, or else the torus cannot be drawn. After specifying the center point of the torus (aslo the center point for the circular path), you have to specify the radius/diameter for both the path and the tube, and then the number of longitudinal and lattitudinal segments.

Wedge (ai_wedge): draws a triangular prism with a face parallel to the XY plane. The details are just like that of ai_box.

Rotate 3D
Command: _rotate3d

Although it looks like the ordinary rotate command, ROTATE3D is a very useful command for those working on 3d modelling. It can rotate a 3d object at any angle, about any axis. Although I advice you to use the first two, lets look at all the methods to rotate a 3d object;

2 Points: Asks you to specify two points on along the axis of rotation. The rotation angle can be entered directly or as a reference.

Object: Aligns the axis of rotation to the selected object. If the object is a line, then the axis is coincident with the line, if the object is a circle or an arc, the axis will pass through the center point perpendicular to the plane containing the circle/arc. If you select a polyline, the axis will be aligned along the selected line segment. After assigning the obkect of rotation, you have to provide the angle of rotation (Rotation Angle/Reference).

Last: Recalls the last used axis of rotation and asks for an angle of rotation.

View: Aligns the axis of rotation along the View direction axis using a point that you will specify. Then enter the angle of rotation. You mayhave to try a few times to get it right.

X Axis: Rotates the object along the X axis, passing from a specified point in the drawing.

Y Axis: Rotates the object along the Y axis, passing from a specified point in the drawing.

Z Axis: Rotates the object along the Z axis, passing from a specified point in the drawing.

SECTION:
Command: _section

SECTION, works just like the slice command. ‘Slice’ splits an object into two by cutting it along a given plane. Very useful while creating solids but requires much attention when preparing for presentations. Whereas there is already a useful command for getting 2D represantations of your 3D models on your layouts; SECTION. This command doesn’t in any way cut your drawing into halves. It will be very useful when you have to draw secitons of complex models. It’s application is just like the SLICE command.

3 points: Used to define the cutting plane using any three points in the drawing.

Object: Asks you to select a Polyline object so that the cutting plane can be aligned with it.

Z Axis: Used to obtain a section perpendicular to the Z axis, by specifying two points on the XY plane.

View: Aligns the cutting plane perpendicular to the direction viewed. Especially useful in perspective view angles.

XY: By specifying a point on the object, you can obtain a section through a plane parallel to the XY plane, passing from that point.

YZ: By specifying a point on the object, you can obtain a section through a plane parallel to the YZ plane, passing from that point.

ZX: By specifying a point on the object, you can obtain a section through a plane parallel to the ZX plane, passing from that point.

Fig.3 A simple application of the SECTION command.

Note: This article has been summarized from the book: AutoCAD 2007 (Pusula Yayıncılık) by the author himself for this purpose.

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