Inventor General Discussion

Inventor General Discussion

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LeedsLad8t6
Posts: 21
Registered: ‎02-07-2014
Message 1 of 8 (366 Views)

Loft ellipse troubles

366 Views, 7 Replies
02-07-2014 12:27 PM
Hello everyone, This is my first post so be gentle :-). I am trying to loft a profile that follows between 2 ellipses but can only get the loft to follow one. Hope the image attached makes things clear enough, I can only have the outer ellipse or the inner, i cannot get the arc profile to follow both these lines at its base. Have narrowed the tool I need to be using down to the loft tool having read "similarish" issues on the forum. Any help would be greatly appreciated. p.s I think it may have something to do with the fully constrained base but am unsure how I would get the arc shape true to the ellipse without it, possibly a tangent contraint somewhere? Kind regards Daniel
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mcgyvr
Posts: 6,845
Registered: ‎12-01-2004
Message 2 of 8 (358 Views)

Re: Loft ellipse troubles

02-07-2014 12:56 PM in reply to: LeedsLad8t6

Always a good idea to 

#1-post the version of Inventor you are using (many of us like to include our Inventor version and even computer hardware in our signatures so its always there)

#2-post the Inventor files

#3-if you can't post the files due to "company secret" info then see if you can post a non secret file that exhibits teh same behavior.
#4-if you can't do 2 or 3 at least post a screenshot showing the problem.

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Contributor
LeedsLad8t6
Posts: 21
Registered: ‎02-07-2014
Message 3 of 8 (343 Views)

Re: Loft ellipse troubles

02-07-2014 03:21 PM in reply to: LeedsLad8t6
Sorry,

I must have not pressed upload, I thought I had attached an image of the problem.

Will upload again in the morning.


Daniel
Contributor
LeedsLad8t6
Posts: 21
Registered: ‎02-07-2014
Message 4 of 8 (326 Views)

Re: Loft ellipse troubles

02-08-2014 04:54 AM in reply to: mcgyvr

Ok I have attached the part and an image, version is 2013 (educational ver. not that it makes a difference here).

 

 

 

Hopefully someone can help.

 

Many thanks

 

Daniel

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JDMather
Posts: 26,585
Registered: ‎04-20-2006
Message 5 of 8 (318 Views)

Re: Loft ellipse troubles

02-08-2014 06:03 AM in reply to: LeedsLad8t6

LeedsLad8t6 wrote:
... having read "similarish" issues on the forum.
...

The problems

1. Sketch 1 is not fully constrained (not even 1 dimension).  You need a horizontal and vertical construction line.  Notice that the sketch points can be dragged anywhere (one of them even off of the ellipse).

After fixing this problem do a Manage>Rebuild All - notice the "sick" sketches.  As a beginner, I recommend that you simply start over rather than getting into what it takes to fix a sick sketch (not that it is hard to fix these two, but as a beginner you need to learn to avoid creating sick sketches altogether - so start over).

 

2. You were using the wrong Loft settings (use Rails, not Centerline).

 

3. You will need to either trim the rails and mirror or create two more profiles at 90° - I recommend the second option as mirror of a loft doesn't always give you the correct geometry.

 

Attach your second attempt here.

 

Please mark this response as "Accept as Solution" if it answers your question.
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Contributor
LeedsLad8t6
Posts: 21
Registered: ‎02-07-2014
Message 6 of 8 (274 Views)

Re: Loft ellipse troubles

02-10-2014 12:58 PM in reply to: JDMather

Hello again,

 

Sorry for the non constrained sketch (I do have some idea of constraints but was seeing if that itself was an issue with the loft not following the rail/s).

 

I have attached a second attempt which I believe to be fully constrained, I have added a sketch at 90deg as you suggested but still no luck with a loft following 2 rails. I have also tried to introduce a third sketch at 45deg but for some reason when I construct it as I did the others the intersections of the projected geometry end slightly past where I need them to be?

 

I have tried using the rails rather then center line but it isn't working, the closest thing i can get is an area loft but even this isn't following the rails. offsetting one of the ellipses to use as a rail doesn't work either as they differ in thickness still in areas :-/.

 

Thank you very much for the help you are giving me.

 

Kind regards

Daniel

 

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JDMather
Posts: 26,585
Registered: ‎04-20-2006
Message 7 of 8 (261 Views)

Re: Loft ellipse troubles

02-10-2014 01:40 PM in reply to: LeedsLad8t6

I would try trimming the ellipse.

Please mark this response as "Accept as Solution" if it answers your question.
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Autodesk AutoCAD 2013 Certified Professional
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Inventor Professional 2015 64-bit
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http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm
Contributor
LeedsLad8t6
Posts: 21
Registered: ‎02-07-2014
Message 8 of 8 (234 Views)

Re: Loft ellipse troubles

02-11-2014 05:14 AM in reply to: LeedsLad8t6

When you say trim the ellipse do you mean the parts beyond the profiles I am trying to loft?

 

I have attached an image of what I mean, the green being what I do not trim.

 

 

Daniel

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