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POPRivet

Variable diameter Helix.

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POPRivet

Hello !

 

I am writing to ask if it is possible to draw an helix of variable diameter, in which the helix starts with a small diameter, then the diameter increases with each turn till half the total height, then the diameter starts decreasing with each turn, to the total height of the spiral.

 

The external contour of the so achieved spiral is a curve, please look at the attached picture.

 

What I am trying to do is to model a spiral spring whose external shape follows a curved shape, not a double cone ( like one conical spiral inverted and aligned over another equal one and then “ unioned “ ).

 

Thank you very much for any help that someone can provide.

 

Yours faithfully

PR

OVAL_SPRING.jpg

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Cad64

I'm not sure exactly what you're trying to do, but I created the object below in 3ds Max using a Spring primitive object and then applied an FFD modifier. Is this what you're trying to do? I'm not sure how to do something like this in Autocad. :unsure:

 

I moved your question to the Autocad 3D Modeling section. http://www.cadtutor.net/forum/forumdisplay.php?20-AutoCAD-3D-Modelling-amp-Rendering

Spring.jpg

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SLW210

There is no indication of what program the OP is using. Might help to know what they have available.

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ReMark

You could create such a model in AutoCAD...well actually half of it anyway then mirror and union it. The AutoCAD HELIX command allows the user to specify different base and top radii.

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POPRivet

Hello Mr Cad64

 

What I am trying to model is exactly what you have achieved.

 

I am using Autocad 2017, not 3ds, so I cannot replicate your workflow.

 

One of the attempts that produced the nearest results to what I want to do, was projecting an helix positioned outside an curved closed surface ( created by lofting three different diameter circles ), the external profile of the so produced surface is much like the spring “ you created.

 

Unfortunately, after projecting the helix ( I tried the three different methods available in AutoCad ) the results were not as expected.

 

The helix projection to the surface creates cross section ellipses ( closed splines ) not a spiral path along the prolate spheroid shape inside it.

 

Only the “ Surface projection VIEW “ method worked, the “ Surface projection UCS/VECTOR “ methods did not projected anything.

 

I am arriving to the conclusion that this is not a task AutoCad can perform, but if you ( or anyone ) reading this post come with new ideas I am always willing to try them.

 

P.S.- Attached is a photograph of the method I tried to create the “ Oval “ spring.

 

Best regards

PR

OVAL_SPRING.png

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POPRivet
There is no indication of what program the OP is using. Might help to know what they have available.

 

 

Mr SLW210

 

You are absolutely wright, I forgot to mention what software I am using.

It’s AutoCad, version 2017.

Sorry about the oversight on my part.

 

Best regards

PR

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ReMark

Since this is not a task that AutoCAD can perform I guess I'll delete my drawing. Failure sucks.

 

Tapered spiral helix.jpg

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POPRivet
Since this is not a task that AutoCAD can perform I guess I'll delete my drawing. Failure sucks.

 

[ATTACH]63647[/ATTACH]

 

 

Hello Mr ReMark

 

Thank you very much for your contribution.

 

I am not completely sure that it can’t be done with AutoCad, but if it can, it is not obvious how to do it, at least for me.

 

Your double conical spring model is perfect, but unfortunately it is not what I am trying to achieve.

 

I would like to obtain a curved external spring profile.

 

If you have more ideas, keep sharing please !

Any and every help is useful !

 

Best regards

PR

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Cad64

I would like to obtain a curved external spring profile.

 

The only way I was able to achieve this was by adding a modifier to the spring object in studio max. The modifier creates a cage around the spring with control points which can be grabbed and scaled in or out to create the curved effect, see image below. I don't know of any way to achieve this in Autocad, but then again, I don't use Autocad for 3D so maybe someone more knowledgeable would have some ideas?

Spring2.jpg

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