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Sweep command rotating "swept" object


mrkmpn

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I am trying to create helical threads based on this tutorial by JD Mather: http://home.pct.edu/~jmather/content/CAD238/AutoCAD%202007%20Tutorial%204.pdf

 

I have done this in the past successfully, but now I can't figure out what I am doing wrong. If I draw the stud so that ends are tapered at a 45 deg. angle as in Mr. Mather's drawing, when I try to sweep the triangle along the helix it rotates the triangle which cuts into the tapered end a little but then only creates lines along the rest of the stud.

 

If I draw the stud so that is is flat on each end, just a plain cylinder, it sweeps properly and once subtracted, gives the proper helical threads.

 

Does anyone have any idea what causes this? Originally I thought maybe I was putting too little height between turns and tried several things before getting the idea that maybe it was the tapered end causing the issue... which seems to be the case.

 

I would also like to note that I am not drawing it to JD Mather's "specs" from the tutorial, I am using the Machinery's handbook to get measurements for diameter, pitch, etc... I made a 5/8 stud, and didn't have an issue, however on 3/4, and 7/8 I have the same problem.

 

 

*Edit*

If it helps any it appears that the triangle is rotating so that the side of the triangle is parallel with the base of the stud.

Edited by mrkmpn
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I'm surprised JD Mather hasn't commented since you reference one of his tutorials.

 

Well, as the learned man would say attach a copy of the drawing to your next post. Drawings speak louder than words. It's a graphical world; why are we using words? Thanks.

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You'd be surprised at how often words fail to describe the problem adequately. Why play 20 Questions? Just wastes everyone's time. Anyway, having an actual drawing does come in very handy for troubleshooting problems.

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Yeah, I've heard all the excuses. Most times we don't need the entire drawing rather we need just enough to see the problem manifest itself.

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I doubt it. It's a single 3D bolt. Once again, there are ways around that too. Does the word Dropbox ring any bells?

 

Thanks for the reply ReMark. When I get a minute I'll redo the drawing and upload it for you. I tried running the sweep command on Mr. Mather's drawing and it appears to also SLIGHTLY rotate the triangle when running the sweep command, but not nearly as bad... and it also works creating the threads. I'm not sure why mine is doing it so bad.

 

I have a few things to take care of 1st this morning and I'll get that uploaded.

 

Thanks again.

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I recall many instances of users having problems with swept objects twisting as they travel along a path (could be a helix or some other geometry). Anyways, I think the fix may be simple but I don't recall it off the top of my head. I'm still an Extrude > Path user and only use Sweep infrequently. Let me see what I can do to find you an answer.

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I recall many instances of users having problems with swept objects twisting as they travel along a path (could be a helix or some other geometry). Anyways, I think the fix may be simple but I don't recall it off the top of my head. I'm still an Extrude > Path user and only use Sweep infrequently. Let me see what I can do to find you an answer.

 

Yeah, I actually tried to extrude path on this but it gave me an error. Might try again when I redo the drawing. As many different things as I've tried to make this work I might have done something to make the EXT not work properly or something. I kind of lost track. Should be able to get something uploaded in the next hour or so.

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Thread Practice.dwg Ok. I redrew it. The 1st time I ran the sweep command, I selected the triangle as the object, then clicked the helix just under where it connects to the helix. When it finished, the triangle rotated to be inline with the base of the stud. I undid the command and this time clicked the end of the helix at the opposite end, and it doesn't appear to have rotated the triangle much, if at all this time.

 

However, when I try to subtract the swept helix from the revolved cylinder, it's not giving me the desired results... It looks like the same cylinder with helical lines across the surface. I am uploading the drawing "pre-subtracted" so you can see what I mean.

 

I also just realized, i recently installed service packs 1 and 2. Could this have caused a problem? If so can I roll back the updates or would I need to reinstall? If this is something I'm not doing right, for the life of me I can't figure out what it is.

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The "problem" is not attributable to service packs.

 

Ok thanks. I just wanted to inform you of any recent changes that could possibly affect the program. (Habit from working on computers)

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No rush ReMark. I've been messing with this for a few days now, and I appreciate the help. I'm not going to complain about having to wait for free help.

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#1 I have never visited this area of the forum before. I would expect this question to be posted in the 3D area. (look at the list of topic titles in this area - they have no interest to me) I just happened to see the Sweep in title by chance.

#2 If someone can't attach a simplified dwg that exhibits all of the behavior of their proprietary data - I don't think they are trying hard enough. (in response to the proprietary data concern) If I had a dollar for every time I suggested to someone that they recreate a "dummy" file that exhibits all the same behavior of their proprietary data, and in the process of creating this "dummy" they actually solved the problem on their own - I could retire.

 

#3 In the example(s) used in my tutorial(s) - notice that there are always lots of layers with all generating geometry preserved on (hidden) layers so that it is easy to reverse engineer, go back to the beginning, whatever....

 

I didn't see any 2D construction geometry or 3D curve to that would enable determining what was done to create the existing geometry. Kind of like an answer on a math test without showing the work required to derive the answer.

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Thanks for your reply sir. I apologize for posting in the wrong area, and honestly didn't necessarily expect you personally to answer my question. The reason I uploaded the drawing after revolving/sweeping everything was to show the results I was getting, as I thought that was being requested.

I didn't look into your drawing enough to notice that you had extra hidden layers, and had never thought of doing that. Thanks for that tip. I will re upload something that conforms to your reply once I have some more time. Busy day today....

 

Thanks for everyone's time and help.

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I didn't look into your drawing enough to notice that you had extra hidden layers, ....

 

 

I guess I need to add more information - should have been nearly impossible to miss?

Also, set DELOBJ=0 to turn off deletion of 2D objects when used to create the 3D. (this information is repeated frequently in the earlier tutorials)

 

Layers.png

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