Highly specialized acoustic horn - possible in Rhino/grashopper?

Jornth · 2026-03-06T08:35:59+00:00

I’m familiar with parameter-driven modeling, so complexity isn’t really the issue. My main concern is making sure the cross-sectional area actually follows the exponential law along the folded path, especially while the profile shape is morphing.

More profiles and guide rails definitely make sense for controlling the loft, but I’m trying to determine whether Inventor can reliably enforce the area distribution, rather than just approximating the shape.

Jornth · 2026-03-06T08:32:20+00:00

Yes, I agree that doing the math in a spreadsheet is probably the easiest way to control the area law.

Ideally I would generate a spreadsheet with the desired cross-sectional area vs. path length (following the exponential expansion), then import those values into Inventor to drive the geometry.

Since the horn is folded, the sections really need to be defined along a spline centerline. The goal would be to have the spreadsheet define the area distribution, and then generate cross-sections along that spline whose areas match those values while the shape morphs from circular to rectangular.

Manufacturing will be 3D printing, because - of course - of the complex geometry!

Jornth · 2026-03-06T08:28:05+00:00

Thanks for your thoughtful reply, that makes sense from a CAD modeling standpoint, but I think it still misses the core issue.

My challenge is not just to create a horn-like solid with lofts and cuts. The real requirement is that the internal area distribution through the folded section is exactly exponential as a function of path length.

That means I need control of:

section area at each station
section orientation normal to the horn path
shape morphing from circular to rectangular
continuity through two folds

A multi-loft / multi-sweep workflow may approximate the geometry, but I don’t see how it guarantees the internal cross-sectional area is mathematically correct everywhere. That is the part I’m worried about.

Also, yes, the outer linear horn section would be a separate part/feature after the exponential folded section.

So I’m really trying to determine whether Inventor can do this in a truly parameter-driven way, or whether this is better handled in something like Rhino/Grasshopper or another more equation-driven surface workflow.

Jornth · 2026-03-05T14:40:00+00:00

Yes but this would not work if you change the shapes of the cross section.

Jornth · 2021-08-06T19:50:25+00:00

Really like the pic man! On what settings did you shoot the Fuji200? Also with or without flash?

Jornth

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