Advanced solid modeling in AutoCAD 2008: HELIX and SWEEP
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Author | Erhan Toker |
| Profession | Architect M.Sc. | |
| Autodesk Authorized Consultant | ||
| Software Specialist | ||
AutoCAD 2007 and higher versions
In my previous article about LOFTING, I have mentioned that I would make an application about drawing a screw. Thus, in this article, I will explain how to draw a basic screw. As I will focus on HELIX and SWEEP commands, I will not draw the screw head and thread end according to rules. First of all, let’s take a look at the final drawing that we would like to accomplish:
Fig. 1
In this drawing, you can see as M10×20 screw. When starting drawing, I created one single thread spacing according to ISO standards (Fig. 2).
Fig. 2
Section that is in orange color has a triangle in the base that has dimensions of 1.5 mm and 60 degree internal angles. We will FILLET the top of this triangle with 0.217 mm radius, and we are rounding roots of screw with the same radius as another triangle will come beside it. Then we obtain the section as shown in figure. By combining entities that make up this section by using PEDIT command, we obtain a closed POLYLINE. After this step, we will create the helix along which we will sweep this section.
Fig. 3
In order to draw the helix that is shown in Fig. 3, it will be better to draw the base square that is shown in Fig. 4.
Fig. 4
After drawing the square with 7.4 x 7.4 dimensions, let’s move on to HELIX command:
Command: HELIX( center of square )
Specify center point of base:
Specify base radius or [Diameter]:( at this point, select the position marked with cross )
Specify top radius or [Diameter] <3.7000>:( enter )
Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <20.0000>: h( thread size spacing )
Specify distance between turns: 1.5001
Specify helix height or [Axis endpoint/ Turns/ turn Height/ tWist]: 21
When you enter command, AutoCAD will prompt the center of helix. Select the center of square. In next step, it asks the base radius of helix. This question is critical, because, if you specify the radius with cursor, then point that you select will also be the starting point. For this reason, it is better to select the mid points of edges of square. Because, it will be easier to align the screw thread that we prepare to the starting point by this way. Next question is the top radius of our helix. We will enter 3.7 in the same manner. After entering these values, here comes the most important parameters of the command. Among these options, there are the axis end point, number of turns, thread size spacing and turning direction. As the thread size spacing is important for us, let’s select < H > and ‘Specify distance between turns’ prompt will come. Let’s enter 1.5001 which is the thread size spacing. Here, we are specifying 1/10,000 times the required. Reason is that, in SWEEP command it is not permitted to touch for the surface along which sweeping will be done. Finally, let’s enter height of our helix as 21. We will cut 1mm of it while we are adjusting the end.
Fig. 5
In next step, we will prepare the outer section surface perpendicular to starting point of helix. In order to do this, you can use ROTATE command once and 3DROTATE once more (Fig. 6).
Fig. 6
After doing this, let’s carry the middle point of base to the section surface so that this starting point will come correspond to starting point of helix. Next step is to make the spiral by using SWEEP command.
Command: SWEEP( orange section surface) 1 found
Select objects to sweep:
Select sweep path or [Alignment/ Base point/ Scale/ Twist]:( helix )
SWEEP command works quite simply. First, we select the section to be sweeped than the path over which the section will be sweeped along (helix). As our threads are formed now, we can draw a cylinder with R=3.75mm and H=20mm in the center of this entity and then combine these two shaped by using UNION command. After that, we can draw a hexagonal with 4mm height at the base and combine it with the previous entity by using UNION command (Fig. 7).
Fig. 7
Finally, let’s draw a cylinder with R=10, H=5 mm and position it as it intersects with the end of our screw and trim the end by using SUBTRACT command (Fig. 8). As I have made this article for advanced users, I quickly passed UNION and SUBTRACT commands. I hope that I could explain about HELIX and SWEEP commands.
Fig. 8
Technorati Tags: AutoCAD, AutoCAD 2007, modeling, 3D, solid, sweep, helix
Bu yazinin Turkce’sini okumak icin basiniz.
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March 26th, 2007 15:28
i am riki from the philippines…. i find your guide very simple yet very informative. i know that by reading this article of yours i can draw objects that i can’t draw before.
April 2nd, 2007 15:46
hello Sir,
I am Lingesh working as designer in harita Seating which is one of TVS Group of company. As I am involving in modelling of A class cushion surface. I tried to import IGES file in auto CAD. but it doesn’t accept that format.Whether can we import IGES in Auto CAD2004 or not? And also has one more doubt.
Can we make spring in Auto CAD 2004?. if it is possible can U send procedure.
Urs friendly
Lingeshan.J
April 27th, 2007 12:44
Yes you can make spring and threads in AutoCAD 2004 using thread.lsp & helix.lsp files if you want more information kindly contact me through this email : rgugr@yahoo.com
May 7th, 2007 11:46
my name is victor. i started learning autocad just one month now. i have mastered a lot in autocad especially from you tutorial. plz i would want u to help me more with information on drafting. bc i want to apply in an engineering company that builds bridge, and they needed me to know how to use civil 3d to draw. thank u
May 11th, 2007 00:56
Great tutorial! I’m using the principles I learned here to draw a spiral staircase. I now have it complete except for the 1/2″ thick acrylic balustrade panels, which I can’t figure out for the life of me. My instinct was to draw a 1/2 thick cylinder of the correct diameter and try to use the handrail (helix) as a boundary for slicing the cylinder, but CAD won’t recognize the helix for this purpose. Any suggestions?
May 21st, 2007 15:42
Hello sir i got a lot of knowledge by these web pages.
but sir i want to do some practicle work plz guide
me kindlly…………….
May 25th, 2007 13:51
Hello Gentle Men,
Thanks very much for this blog.
It’s very informative, well designed, and user friendly.
Your photos add a very professional touch to the site.
Maren
June 22nd, 2007 21:54
Sir,
I want to draw the thread of a bolt and for that I did draw a spiral with the helix lisp and extrude a triangle with the helix as a path (using ACAD2004).
The result is that the shape of the triangle is rotating along the helix path.
What is the trick to keep the triangle parallel to the outside of the bolt?
July 3rd, 2007 03:16
Mr Toker, Very Informative and a very direct approach to this problem, I have been wondering how to approach a similar situation I believe this information will apply. On another subject, I have been working with some Autolisp code and have a great deal of success creating a variety or subroutines in a varied area of application. I have reached a dead end and am looking for some example code of how to deal with / Modify Solids with code. Am I confined to only (command “whatever” “” ) approach, can I work with solids from an “entmake” approach assigning 3d coordinates ? Where do I look for an answer to this problem. ,, PS I use a Legal Registered version of Architectural Desktop 2007, is there an online resource from Autodesk that I am not aware of. Thank you very much, Sincerely Bryan
July 3rd, 2007 08:34
Hi Bryan,
I’m afraid you can not modify or create solids with standard AutoLISP functions. You have to checkout Visual LISP (vla_xxxxx) functions. Or please ask this question to Muharrem. He’s a real Visual LISP expert
August 19th, 2007 09:58
sir toker,
do you have any tuitorial how to make a spring in a curve path?
Thank you very much
September 7th, 2007 21:47
sir toker,
we have developed a product to import iges file into autocad, could you please evaluate our software and make some comments?
thanks
John
September 8th, 2007 13:15
I type helix into the command line on auto cad 2005 and it doesn’t recognise it. strange
September 10th, 2007 08:50
Hello John,
HELIX command available after Acad 2007.
How can I download your project and sample IGES files?
September 19th, 2007 14:09
John,
You can download 3D spiral autolisp routine from the t’interweb which will allow you to create 2D and 3D spirals in earlier versions.
October 23rd, 2007 11:41
Hello John,
can you help me with lofting error in AutoCAD?
I have two different cross-sections: one big and one small triangle. When I use lofting by path solid object has correct bounds, like this:
X = 0.0000 , Y = 0.0000 , Z = 0.0000
X = 100.0000 , Y = 100.0000 , Z = 100.0000
But when I use lofting by cross-sections only solid has incorrect bounds:
X = -0.0010 , Y = -0.0010 , Z = -0.0010
X = 100.0010 , Y = 100.0010 , Z = 100.0010
And this error reflect to other operation. When I try to union conus and lofting solid difference in 0.001 units at the edge sometimes cast ACIS modeling error.
Alexander (Russia)
November 3rd, 2007 09:50
hello toker..i found that your manual on drawing screw is very helpful..but now i have difficulties on how to draw internal thread in a cylinder,.hope that u could help me on that matter..thank you..
December 13th, 2007 21:30
does anybody knows how to make a roller chain or an engine belt with teeth? or array an object in elleptical shape or any other shape besides a circle. thanks
December 14th, 2007 20:33
does anybody knows how to make a roller chain or an engine belt with teeth? or array an object in elliptical shape or any other shape besides a circle. thanks
March 21st, 2008 18:32
I have followed everything as far as I can tell but when I go to sweep my object I get a message saying ‘Unable to sweep the selected object’. What am I doing wrong?
March 22nd, 2008 10:40
Hello Chris,
Be sure that profile polyline is closed. And also notice that no crosing or overlapped segments are allowed.
Hope this helps..
April 29th, 2008 11:31
sir
may I see how to draw a thread according to rules with ACAD 2004,2005,2006.
May 2nd, 2008 05:08
Hi,
Where can i find some information about the thread end?? If you really want to draw a real thread, you have to know how make the real shape for the thread end.
I really need to know that….
June 26th, 2008 09:55
chris,
i had the ‘unable to sweep the selected object’ error as well. turns out that the object i was trying to sweep (in my case a circle) overlapped on itself around the bends of the path i was sweeping along, so i increased the diameter of the bends and the object swept fine.
July 2nd, 2008 00:55
hol soy latino quisiera me expliques como cargo el lisp helix qu ebaje de web par poder hacer helicoidales en esplaol pls
July 31st, 2008 17:06
I am having trouble with the Helix command in AutoCAD 2008. I have a PDF screen capture file that I would like to send to you to illustrate my problem. Thank you.