Flaps Normal to mesh surfaces for Fabrication

Hi all,

I recently had to prepare some file for fabrication. I got it figured out with Andrei Jipa's help; just wanted to add to the knowledge base of the grasshopper community.

The geometry is a deformed geodesic sphere generated from Kangaroo physics:

I wanted to add flaps on to each subsurface like this precedent I found:

https://tesselion.wordpress.com/page/3/

I had to find normal of each sub-surface and extruded the edges of each individual triangles.

However, note that the extruded flaps are overlapped at nodes.

The flaps could be shortened with 'extend curve'. (Thanks to Andrei's help on this)

It could be unfolded with 'Rotate Axis' along the curves to achieve this for fabrication on flat sheets:

Hope it helps.

Best regards,

Zhini

Attachments:

160108 Fabrication.gh, 23 KB

Replies to This Discussion

Permalink Reply by Andrei on February 2, 2016 at 6:05am

Hi Zhini,

Thanks for posting this. Great work!

If I may add one more comment: what you did so far helps with visualising your system. In terms of computation time for getting fabrication files, because everything is based on triangles, you might want to consider this:

You can measure for each mesh face the three edge lengths and recreate a triangle with those edge lengths on the XY plane. From the flat triangle you can create the flaps directly on the XY, therefore avoiding orienting and rotating geometries.

This is possible because of the triangle SSS congruency theorem :

http://www.mathopenref.com/congruentsss.html

Best

Andrei

Permalink Reply by Zhini Poh on February 3, 2016 at 11:17am

Thanks Andrei!

I will have a look at that method.

For now, I am just fabricating equilateral triangles; the alternate surfaces are culled. The physical model is not really a perfect sphere but it does the job.

Appreciate your help! :)

Best,

Zhini

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