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Oct 18
Thursday
3D, 3D Modeling, AutoCAD 2007
Advanced solid modeling in AutoCAD 2008: HELIX and SWEEP

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
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
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
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
Fig. 4

After drawing the square with 7.4 x 7.4 dimensions, let’s move on to HELIX command:

Command: HELIX
Specify center point of base:
( center of square )
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
Specify distance between turns: 1.5001
( thread size spacing )
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
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
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
Select objects to sweep:
( orange section surface) 1 found
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
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
Fig. 8

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30 Responses to “ Advanced solid modeling in AutoCAD 2008: HELIX and SWEEP ”
  1. 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.

  2. Lingeshan.J

    Apr 2, 2007
    Reply

    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

  3. 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

  4. 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

  5. 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?

  6. Anil Sharma

    May 21, 2007
    Reply

    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…………….

  7. Maren Swakei Mr

    May 25, 2007
    Reply

    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

  8. Edme Focant

    Jun 22, 2007
    Reply

    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?

  9. Bryan Adkins

    Jul 3, 2007
    Reply

    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

  10. 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 :)

  11. sir toker,
    do you have any tuitorial how to make a spring in a curve path?

    Thank you very much

  12. 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

  13. I type helix into the command line on auto cad 2005 and it doesn’t recognise it. strange

  14. Hello John,
    HELIX command available after Acad 2007.
    How can I download your project and sample IGES files?

  15. 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.

  16. 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)

  17. 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..

  18. 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

  19. 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

  20. 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?

  21. Hello Chris,
    Be sure that profile polyline is closed. And also notice that no crosing or overlapped segments are allowed.
    Hope this helps..

  22. sir
    may I see how to draw a thread according to rules with ACAD 2004,2005,2006.

  23. 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….

  24. 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.

  25. PERCY KLEE

    Jul 2, 2008
    Reply

    hol soy latino quisiera me expliques como cargo el lisp helix qu ebaje de web par poder hacer helicoidales en esplaol pls

  26. Mark Loomis

    Jul 31, 2008
    Reply

    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.

  27. Ahmed Butt

    Sep 24, 2008
    Reply

    Thankyo you very much for this wonderful tutorial. I’ve been searching for this artical for many months on the net and i want to thank you deeply from my heart for this tutorial.

    Hoping to have more helpful tutorials like this in future…..

    Y O U R O K Z !!!!

  28. Syarip Hidayat

    Nov 10, 2008
    Reply

    Can we drawing bolt/nuts using autoCAD 2006? or is there any software to help it? please give your advices.

    Thanks and Best Regards,

    Syarip Hidayat

  29. Hi, I tried your helix tutorial but I have some problem. I put the pattern on position the same on instruction,but when i command sweep,the pattern is rotating and sweep in to path.


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