Command: _3Dorbit

Those who make drawing in 3D by AutoCAD may want to rotate objects also out of Z axis. Most of us try to do this by changing UCS. However, it is a very laborious work to change UCS first and then use ROTATE command and change UCS back to its original. For this reason, AutoCAD introduced a new command named as 3DROTATE. Now, let’s take a close look at this command together…:
Fig. 1
In Fig. 1, our final aim is to draw the half bowl on the right side. Each user determines a different drawing strategy for each drawing. Here, we will first start by drawing a half circle to any location, and then use ROTATE3D command to rotate it in upwards direction. After doing this, we will draw an axis line and make a half tour for our arc around this axis. Now, you draw the horizontal arc and axis lines. And then, let’s apply ROTATE3D command together.

Command: 3DROTATE Current positive angle: ANGDIR=counterclockwise ANGBASE=0

As we will mostly deal with angles, AutoCAD will give us information about current angle direction (ANGDIR) and current starting angle (ANGBASE). Right handle rules, which we are already familiar from vectors in physics, are also adopted by the engineers who made AutoCAD. While thumb of your right hand show the axis direction, keep your remaining fingers as if you are holding something, so these fingers will show the rotation direction.
Fig. 2
Select objects:
Specify first point on axis or define axis by
[Object/Last/View/Xaxis/Yaxis/Zaxis/2points]: 2p

Before converting our arc into half bowl, we have to bring it to upwards direction. In order to do this, we have to rotate our arc around 1-2 axis (Fig.1). As it can be seen, AutoCAD offers us many options for defining axis. As I am familiar with the right hand rule, my favorite is always 2 points. If we look at right hand rule in Fig. 2, if we select 1-2 axis line first from ends no.1 and later no.2; then, while our thumb is pointing point 2, our other fingers will show + (plus) rotation direction.

Specify first point on axis : [1]
Specify second point on axis : [2]
Specify rotation angle or [Reference] : 90

When the command is completed, then our arc will be upwards. Before this stage, we will need an aiding line in Z direction as a rotation axis. This line is marked with red in Fig. 1. Final command that we will use is REVSURF. This command revolves any entity around any axis selected.

Command : REVSRURF
Select object to revolve : (select our line here)
Select object to define axis of revolution : (select red line here)
Specify start angle <0> :
Specify included angle (+=ccv, -=cw) <360> : 180

Answer of this prompt is 180 degree. If we have drawn the red axis line from up to down ( as there is no aiding line, it will be very hard in this example ), then our bowl would be exact mirror copy of bowl shown in Fig. 1.

Command:_Extrude

Let us first remember what EXTRUDE command is before going into detail. This information provides you to better understand the use of EXTRUDE command. The definition of EXTRUDE can be put in this way: Forcing to flow a pre-heated metal or plastic material in high pressure through a mold which is constructed for forming an target object.
Fig.1
The modeling toolbar is newly designed in AutoCAD 2007. Yet, some functions of it have already been exist in older versions. Likewise, the method of solid modeling and EXTRUDE command are ways of transforming the object from 2D to 3D which is frequently used in other versions.
Let us examine the method.
Fig.2
Typing ‘Extrude’ into the command line and pressing enter or selecting the icon marked in the modeling toolbar above request the object to be extruded.
Select objects to extrude:
Fig.3
Upon the selection of the object, we are asked for which one of the four extruding methods will be used.
Specify height of extrusion or [Direction/ Path/ Taper angle] <36.2829>:

Let us go on with the first method. You can enter a value that designates the height among the Z axis or point dynamically with mouse.
Fig.4 An Extrude generated by entering the height only.

Let us extrude an object with Taper Angle option.

In this case, our object is a circle. Run the command and select the object.
Select objects to extrude:
Fig.5
Taper angle is selected.

Specify height of extrusion or [Direction /Path /Taper angle] <0>: T

The value of angle is entered.
Specify angle of taper for extrusion <0>:15

The desired height is chosen.

Specify height of extrusion or [Direction/Path/Taper angle] <0>:100

When the input parameters are set, an object like the one below should be formed.
Fig.6
Now let us check for what the input parameters (angle and height) are used by looking the object sideways.
Fig.7
Let us extrude an object with Path option.
Specify height of extrusion or [Direction/ Path/ Taper angle] <0>: P
Fig.8
A POLYLINE can be selected for path (You can construct a pline by typing it into the command line). The solid model should be seen like the one below after the command is concluded and appropriate view angle is selected.
Fig.9
Direction option
Direction method is similar with path option. The coordinates of the points that the object is going to be extruded have to be specified. Let me explain it with an example.
Run the extrude command and choose the direction option.
Select objects to extrude: Specify height of extrusion or [Direction/Path/Taper angle] <0>: D

The start and end points of the direction are specified.
Specify start point of direction: 0,0,0 Specify end point of direction: 0,10,40
Fig.10
To better understand it, run the ‘DIST’ command and choose the first and the second points.

Command:di
DIST Specify first point: Specify second point:
Delta X = 0.0000, Delta Y = 10.0000, Delta Z = 40.0000