3D Modeling 8: Using SWEEP command
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Author | Orhan Toker |
| Profession | Architect M.Sc. | |
| Autodesk Authorized Consultant | ||
| Database Specialist | ||
AutoCAD 2007 and higher versions
SWEEP command, which is one of the new features that came with AutoCAD 2007, can be considered as an advanced version of EXTRUDE command. Both EXTRUDE and SWEEP commands are used for creating a 3D solid by dragging a profile along a path.
The main difference between the two commands is that in SWEEP command, you can automatically make the profile perpendicular to path; you can scale the profile along the path and rotate it. On the other hand, “taper angle” option of EXTRUDE command does not exist in SWEEP command.
Let’s come to SWEEP command. The first example that comes in mind for SWEEP command is a spiral spring. This example is very popular because it explains the fundamental use of this command very well. In my opinion, you can learn about the fundamental concepts of SWEEP command by reading “Advanced solid modeling in AutoCAD 2007: HELIX and SWEEP” that was written by Erhan. Let’s continue by drawing a spring 
Command: _sweep
Current wire frame density: ISOLINES=8
Select objects to sweep: (select the circle)1 found
Select objects to sweep: (press ENTER)
Select sweep path or [Alignment/Base point/Scale/Twist]: (press ENTER)
Fig.2
As you can see, this is the most basic way to show how SWEEP command works. Which is simply dragging an entity around a path. Unless you mention other vise, entity is automatically taken perpendicular to the path and centered to it.
Now, let’s take a look at options of SWEEP command:
Alignment: Unless you mention otherwise, it aligns the entity perpendicular to path. Another option is to accept the own angle of profile.
Base Point: Unless you mention otherwise, it aligns the places the profile on the center of path.
Fig.3
Scale: You can scale the profile along the path. In the example below, you can find the solid which is scaled and twisted by half rotation.
Fig.4
Command: _sweep
Current wire frame density: ISOLINES=8
Select objects to sweep: (select the square) 1 found
Select objects to sweep:
Select sweep path or [Alignment/Base point/Scale/Twist]: s
Enter scale factor or [Reference]<1.0>: 2
Select sweep path or [Alignment/Base point/Scale/Twist]: t
Enter twist angle or allow banking for a non-planar sweep path [Bank]<0.0>: 180
Select sweep path or [Alignment/Base point/Scale/Twist]:
Twist: This option is the most important option that separates SWEEP from EXTRUDE, just like “scale”. You can rotate, twist, the profile along the path.
Now, take a look at below examples to see what kind of variations you can make and repeat the examples by yourself.
Fig.5
In this example, after you select your circle for SWEEP, make the “scale” setting as 2 and try once more by selecting the path from its point 1 and then next time by selecting it from its point 2.
Fig.6
This time, try using the “basepoint” option after selecting the square.
Fig.7
In this example, use ‘basepoint’ and ‘twist’ options. You can download the file that can be used to work on the example from here.
Have a nice day.
See previous articles of series : See “3D Modeling” chapter in AutoCAD Lessons.Technorati Tags: AutoCAD, AutoCAD 2008, 3D Modeling, solid modeling
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August 2nd, 2007 12:32
Hi
Can you explain to me how to draw a curved-angled 3D object like this one: http://www.montkemijadd.hr/mont/mont_kut_Mallorca.html
The hole in bathtub is, as you can see, very non linear in design. Usually, to draw something like it, firstly i would draw a exact top view. Problem with this example is that when I draw a top view of a bath’s hole (which is non-linear curved) using combination of Polyline and Arc, and joining them together with pedit command, a final resoult would be a exactly same curved polyline, same as on top view on that web page, BUT I cant Extrude that poliline. I get error “Cannot sweep or extrude a self-intersecting curve” which I don’t know how to fix…
Please, send an answer to my email too.
Thanks in advance!
August 2nd, 2007 13:33
Hi Ivan,
Unfortunatally it’s very hard to create that kind of models in AutoCAD. You can use Rhine 3D to modeling it.
Thank you very much
August 3rd, 2007 23:31
Your sweep to create a sping in nice Orhan but unfortuately, most springs are closed at the ends so that they are flat and most are also ground. Creating a relistic and therefore useable spring in a bit more complex.
There are several coil spring routines that do that which have been around for several years. See if you can find 3dcspr.lsp for an example.
Bob Price
A*G*M
August 4th, 2007 09:17
You’re right RBPrice,
I’ll take care this point in my “SLICE” lesson.
Thank you
August 8th, 2007 11:28
Just to say, I’ve found a solution for my problem. The command is “presspull”. This command recognizes a drawing as a “face” and with it you can extrude any kind of face drawing, no matter if it is linear or curved…
Here’s the 3D picture of mentioned bathtub: http://imagedub.com/images/jdv1186565247v.jpg
BTW, GREAT BLOG! I’m enjoying it very much!
August 10th, 2007 21:17
Very well Ivan,
Dou you want to tell us how you did. I mean dou you want to write this as an article of daily autocad
September 6th, 2007 18:35
I am trying to locate a spiral command or at least get one to work in autocad 2007.
I used spiral command a lot before I upgraded. I previously had 2004LT and then 2006 LT. At that time the spiral command was a lisp file.
Any help would be greatly appreciated.
Thanks,
Bobby Green
September 11th, 2007 09:53
Orhan, thanks for offer. When I’ll manage to get some time I’ll post you an article about it.
Keep up the great work!
January 22nd, 2008 14:25
Dear sir,
I am very glad to see your web and I solve many of problem in 3d modeling.
thank you.
January 28th, 2008 19:11
Ivan you made my day thanks to that command presspull!. Really thankyou!!! and this post. Thanks for this web
February 9th, 2008 08:22
Dear sir,
I am very very thanks you. I don’t solve this modeling unless if you teach …….. God bless you!!!!!!!!!!
April 18th, 2008 23:01
Using this command along a spline will only allow you to twist in one direction. This would be fine if this was an ordinary polyline. You could just use a mirror command. Using a negative number such as -90 will make it twist 270 degrees. Do you have any ideas on how to remedy this?
Thanks,
Curt