Advanced solid modeling: Loft
With AutoCAD 2007, 3 dimensional drawing capabilities have increased dramatically. From now on, it is possible to draw helix and spiral. Moreover, it is also possible to use these entities as PATH, so that you can drag different profiles along them and create new 3 dimensional entities. By this way, main disadvantage of AutoCAD against Microstation™ has been overcame, thus now it is possible to draw screws or similar 3 dimensional entities. Besides, LOFTING has been added to the program as of 2007 version, which is possible in 3D Studio for years but not possible in AutoCAD. In this article, I will try to explain LOFT command to you by giving two examples.
Fig. 1
In first example, we will create the 3-dimensional entity shown on the right side by dragging 3 circles and 1 square along the path with red color. Actually, dictionary meaning of LOFT is attic and LOFTING means to throw something into air. If you imagine an attic carefully, you will notice that it is created by dragging a triangle along a rectangular plan. LOFT command in AutoCAD works the same way. It creates a 3-dimensional entity by dragging a number of sections over a certain path. However, there are certain rules while drawing:
1. Entities that make up the sections must form closed surfaces. These entities can be arcs, elliptical arcs, ellipses, circles, 2D polylines and 2D splines.
2. Entities that make up section must be chosen at a definite number.
3. Drawing that makes up the path can be either a closed or open route. Line, arc, elliptical arc, spline, ellipse, helix, circle, 2 or 3-dimensional polyline can be used to draw the path. If more than one main entity will be used (arc, line, elliptical arc), then they must be aligned from end to end and they must be combined into one polyline by using PEDIT command.
4. If sections will be dragged along guide lines as shown in Fig. 2, then guide lines must be again made up of polylines and/or splines. Guide lines cannot be closed routes.
Now, let’s proceed to our example:
Prepare the drawing that is shown on the left side in Fig. 1. While creating this drawing, I drew the red circle with 200 diameter, small circle with 40 diameter and the square as 50×50 dimensions. You can create different entities by changing the dimension and form the section as you like and create different entities. After completing the drawing, let’s proceed to LOFT command:
Command: LOFT ( Modeling toolbar, ) Select cross-sections in lofting order: 1 found, 2 total
After entering command, it will prompt us to select the sections in order!. You can start from any section. For example, I selected 4 sections one by one by starting from square and moving on in clockwise direction. I suggest you to make selection in the same manner. After selecting of entities are completed, than you can end selection by pressing ENTER. After doing this, this is what you will see on the screen:
Enter an option [Guides/ Path/ Cross-sections only] : p
As we will drag the sections along a path in our first example, we will use PATH option, and we select red circle as path. After making selection, AutoCAD will create 3 dimensional entity that is shown on the right side in Fig.1. If you examine this entity carefully, you will see that a section, which is passing from square to circle and again back from circle to square, is dragged along a circular path. It is surprising but true. From now on, AutoCAD can draw such shapes. Now, let’s move on to next example
Fig. 2
In this example, we will use the second method and use guide lines. In this method, again, first the sections are entered. And, rules for entering a section are same. However, guide lines must be defined as they will show the outer boundaries of the section in 3rd dimension. In our example, I showed guide lines in red color.
Command: LOFT ( Modeling toolbar, )
Select cross-sections in lofting order: 1 found, 2 total
Enter an option [Guides/ Path/ Cross-sections only] : G
Select guide curves:
As soon as we select the entities that are shown in red color, we obtain 3-dimensional entitiy that is shown on the right side. By this way, we learned LOFT command. In my next article, I will try to explain how to draw a screw by using helix and SWEEP command.:
Fig. 1
In first example, we will create the 3-dimensional entity shown on the right side by dragging 3 circles and 1 square along the path with red color. Actually, dictionary meaning of LOFT is attic and LOFTING means to throw something into air. If you imagine an attic carefully, you will notice that it is created by dragging a triangle along a rectangular plan. LOFT command in AutoCAD works the same way. It creates a 3-dimensional entity by dragging a number of sections over a certain path. However, there are certain rules while drawing:
1. Entities that make up the sections must form closed surfaces. These entities can be arcs, elliptical arcs, ellipses, circles, 2D polylines and 2D splines.
2. Entities that make up section must be chosen at a definite number.
3. Drawing that makes up the path can be either a closed or open route. Line, arc, elliptical arc, spline, ellipse, helix, circle, 2 or 3-dimensional polyline can be used to draw the path. If more than one main entity will be used (arc, line, elliptical arc), then they must be aligned from end to end and they must be combined into one polyline by using PEDIT command.
4. If sections will be dragged along guide lines as shown in Fig. 2, then guide lines must be again made up of polylines and/or splines. Guide lines cannot be closed routes.
Now, let’s proceed to our example:
Prepare the drawing that is shown on the left side in Fig. 1. While creating this drawing, I drew the red circle with 200 diameter, small circle with 40 diameter and the square as 50×50 dimensions. You can create different entities by changing the dimension and form the section as you like and create different entities. After completing the drawing, let’s proceed to LOFT command:
Command: LOFT ( Modeling toolbar, ) Select cross-sections in lofting order: 1 found, 2 totalAfter entering command, it will prompt us to select the sections in order!. You can start from any section. For example, I selected 4 sections one by one by starting from square and moving on in clockwise direction. I suggest you to make selection in the same manner. After selecting of entities are completed, than you can end selection by pressing ENTER. After doing this, this is what you will see on the screen:
Enter an option [Guides/ Path/ Cross-sections only] : p
As we will drag the sections along a path in our first example, we will use PATH option, and we select red circle as path. After making selection, AutoCAD will create 3 dimensional entity that is shown on the right side in Fig.1. If you examine this entity carefully, you will see that a section, which is passing from square to circle and again back from circle to square, is dragged along a circular path. It is surprising but true. From now on, AutoCAD can draw such shapes. Now, let’s move on to next example
Fig. 2In this example, we will use the second method and use guide lines. In this method, again, first the sections are entered. And, rules for entering a section are same. However, guide lines must be defined as they will show the outer boundaries of the section in 3rd dimension. In our example, I showed guide lines in red color.
Command: LOFT ( Modeling toolbar, )
Select cross-sections in lofting order: 1 found, 2 total
Enter an option [Guides/ Path/ Cross-sections only] : G
Select guide curves:
As soon as we select the entities that are shown in red color, we obtain 3-dimensional entitiy that is shown on the right side. By this way, we learned LOFT command. In my next article, I will try to explain how to draw a screw by using helix and SWEEP command.:
With AutoCAD 2007, 3 dimensional drawing capabilities have increased dramatically. From now on, it is possible to draw helix and spiral. Moreover, it is also possible to use these entities as PATH, so that you can drag different profiles along them and create new 3 dimensional entities. By this way, main disadvantage of AutoCAD against Microstation™ has been overcame, thus now it is possible to draw screws or similar 3 dimensional entities. Besides, LOFTING has been added to the program as of 2007 version, which is possible in 3D Studio for years but not possible in AutoCAD. In this article, I will try to explain LOFT command to you by giving two examples.
Fig. 1
In first example, we will create the 3-dimensional entity shown on the right side by dragging 3 circles and 1 square along the path with red color. Actually, dictionary meaning of LOFT is attic and LOFTING means to throw something into air. If you imagine an attic carefully, you will notice that it is created by dragging a triangle along a rectangular plan. LOFT command in AutoCAD works the same way. It creates a 3-dimensional entity by dragging a number of sections over a certain path. However, there are certain rules while drawing:
1. Entities that make up the sections must form closed surfaces. These entities can be arcs, elliptical arcs, ellipses, circles, 2D polylines and 2D splines.
2. Entities that make up section must be chosen at a definite number.
3. Drawing that makes up the path can be either a closed or open route. Line, arc, elliptical arc, spline, ellipse, helix, circle, 2 or 3-dimensional polyline can be used to draw the path. If more than one main entity will be used (arc, line, elliptical arc), then they must be aligned from end to end and they must be combined into one polyline by using PEDIT command.
4. If sections will be dragged along guide lines as shown in Fig. 2, then guide lines must be again made up of polylines and/or splines. Guide lines cannot be closed routes.
Now, let’s proceed to our example:
Prepare the drawing that is shown on the left side in Fig. 1. While creating this drawing, I drew the red circle with 200 diameter, small circle with 40 diameter and the square as 50×50 dimensions. You can create different entities by changing the dimension and form the section as you like and create different entities. After completing the drawing, let’s proceed to LOFT command:
Command: LOFT ( Modeling toolbar, ) Select cross-sections in lofting order: 1 found, 2 total
After entering command, it will prompt us to select the sections in order!. You can start from any section. For example, I selected 4 sections one by one by starting from square and moving on in clockwise direction. I suggest you to make selection in the same manner. After selecting of entities are completed, than you can end selection by pressing ENTER. After doing this, this is what you will see on the screen:
Enter an option [Guides/ Path/ Cross-sections only] : p
As we will drag the sections along a path in our first example, we will use PATH option, and we select red circle as path. After making selection, AutoCAD will create 3 dimensional entity that is shown on the right side in Fig.1. If you examine this entity carefully, you will see that a section, which is passing from square to circle and again back from circle to square, is dragged along a circular path. It is surprising but true. From now on, AutoCAD can draw such shapes. Now, let’s move on to next example:
F. 2
In this example, we will use the second method and use guide lines. In this method, again, first the sections are entered. And, rules for entering a section are same. However, guide lines must be defined as they will show the outer boundaries of the section in 3rd dimension. In our example, I showed guide lines in red color.
Command: LOFT ( Modeling toolbar, )
Select cross-sections in lofting order: 1 found, 2 total
Enter an option [Guides/ Path/ Cross-sections only] : G
Select guide curves:
As soon as we select the entities that are shown in red color, we obtain 3-dimensional entitiy that is shown on the right side. By this way, we learned LOFT command. In my next article, I will try to explain how to draw a screw by using helix and SWEEP command.ig
Fig. 1In first example, we will create the 3-dimensional entity shown on the right side by dragging 3 circles and 1 square along the path with red color. Actually, dictionary meaning of LOFT is attic and LOFTING means to throw something into air. If you imagine an attic carefully, you will notice that it is created by dragging a triangle along a rectangular plan. LOFT command in AutoCAD works the same way. It creates a 3-dimensional entity by dragging a number of sections over a certain path. However, there are certain rules while drawing:
1. Entities that make up the sections must form closed surfaces. These entities can be arcs, elliptical arcs, ellipses, circles, 2D polylines and 2D splines.
2. Entities that make up section must be chosen at a definite number.
3. Drawing that makes up the path can be either a closed or open route. Line, arc, elliptical arc, spline, ellipse, helix, circle, 2 or 3-dimensional polyline can be used to draw the path. If more than one main entity will be used (arc, line, elliptical arc), then they must be aligned from end to end and they must be combined into one polyline by using PEDIT command.
4. If sections will be dragged along guide lines as shown in Fig. 2, then guide lines must be again made up of polylines and/or splines. Guide lines cannot be closed routes.
Now, let’s proceed to our example:
Prepare the drawing that is shown on the left side in Fig. 1. While creating this drawing, I drew the red circle with 200 diameter, small circle with 40 diameter and the square as 50×50 dimensions. You can create different entities by changing the dimension and form the section as you like and create different entities. After completing the drawing, let’s proceed to LOFT command:
Command: LOFT ( Modeling toolbar, ) Select cross-sections in lofting order: 1 found, 2 totalAfter entering command, it will prompt us to select the sections in order!. You can start from any section. For example, I selected 4 sections one by one by starting from square and moving on in clockwise direction. I suggest you to make selection in the same manner. After selecting of entities are completed, than you can end selection by pressing ENTER. After doing this, this is what you will see on the screen:
Enter an option [Guides/ Path/ Cross-sections only] : p
As we will drag the sections along a path in our first example, we will use PATH option, and we select red circle as path. After making selection, AutoCAD will create 3 dimensional entity that is shown on the right side in Fig.1. If you examine this entity carefully, you will see that a section, which is passing from square to circle and again back from circle to square, is dragged along a circular path. It is surprising but true. From now on, AutoCAD can draw such shapes. Now, let’s move on to next example:
F. 2In this example, we will use the second method and use guide lines. In this method, again, first the sections are entered. And, rules for entering a section are same. However, guide lines must be defined as they will show the outer boundaries of the section in 3rd dimension. In our example, I showed guide lines in red color.
Command: LOFT ( Modeling toolbar, )
Select cross-sections in lofting order: 1 found, 2 total
Enter an option [Guides/ Path/ Cross-sections only] : G
Select guide curves:
As soon as we select the entities that are shown in red color, we obtain 3-dimensional entitiy that is shown on the right side. By this way, we learned LOFT command. In my next article, I will try to explain how to draw a screw by using helix and SWEEP command.ig
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