Dome with Fins Construction Question

[timsefton]

Any sugestions on how better to represnet this shape - its a dome, which the height is a parameter (elispe), and the fins coming off the tope of the dome are sousposed to be angled (thicker at the bottom then the top), and the hight of the fins needs to increase as they move towards the center.

I created a dome with a repeating pattern of fins but having trouble getting the varying thickness of each fin along with the varying height - the whole part I'm wanting it to be a thin wall shell that can be cast in aluminum and then cleaned up wiht cnc -

any suggestions much appreciated.

[JDMather]

Attach the file here.
What version of Inventor are you using?

[timsefton]

Version is 2012

[JDMather]

Attach the ipt file here.

[JDMather]

Something like this?

[timsefton]

Yes,  pretty close - the solid must be circular - the fins go from thick at the base to think at the tip and the center fin is taller then the fins next to it.

Your thougths on construction techique ?

Thanks,

Tim

[timsefton]

Here is the design that I created so far - just not quite robust in the design, had to thicken each rib by hand and could get any type of automated change  in hight of the ribs.

[JDMather]

Your first sketch isn't constrained - you might take a look at this document http://home.pct.edu/~jmather/skillsusa%20university.pdf

[JDMather]

When I add this missing dimension - it doesn't make sense.
Parts can't be manufactured with dimensions like this.

[timsefton]

Hi JD,

Not concerned with the constraints or the dimensions at this point - just wanting to get a better CAD model for the fin construction - one where we can experiment with the dome hight along with the fin height and width and spacing, without rebuilding the model  I understand the part will need to be constrained and dimensioned prior to build.  Manufacturing will be done from CAM file for cutting a foam mold that will then be cast.

To get the changing height of the ribs in your example - how did you do that ?

Tim

[JDMather]

Maybe something like this?

[JDMather]

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@tim.sefton wrote:

Hi JD,

Not concerned with the constraints or the dimensions at this point -

Tim

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Oh, in that case I can't help you.  As a machinist - I'm always concerned about constraints and dimensions.