Problem with density in minimal surfaces

Grasshopper
,
1

Hello,

I found this isosurfacer: Gyroid structure with milipede - #6 by BrianJ made by Daniel Piker. It work great but… I have problem with making some structures with heigh density.

For example I need to create Neovius structure with: 30%, 40%, 50%, 60%, 70% density. I need to 3D print this structure and compare mechanical properties between this densities. Density is increased by adding wall thicknes size. When Wall thicknes is 0.731 density is 32%. When wall thicknes is 0.732 density is 65% And nothing between this. So I can not create 40% 50% and 60% :frowning:

For better understanding what I mean look at this:

neovius
neovius2174×738 101 KB

Please can someone help me with this ? This is my research and resulsts may be used in medicine or another industry… So I really need to solve this problem, because without thiss will be over for my research.

Thank you for answer

2

You can right click a slider to change the number of digits if you want finer adjustments.
You might also want to increase the resolution of the isosurface.

Also, it looks like your volume measurement is flipping since those 2 values you mention sum to approx 100. These types of surface divide space into 2 volumes, or 3 if you have a wall thickness.
Are you doing a boolean intersection with a cube to get the closed volume? You need to make sure you’re choosing consistently between the volumes.

3

Thank you for your answer. I set to 6 digits but this did not work. The problem is still same: 0.731178 = 32% and 0.731179 = 65%.

neovius2
neovius21703×586 111 KB

I don’t understand you very well. I do not have experience with Rhino before. All What I am doing is that I changing iso value and looking to solid percentage. Like in this screen:

isosurface
isosurface1627×563 92.9 KB

This is my file. Please can you look on it ? Isosurfacer_solid2.gh (17.9 KB)

4

Look at the geometry it is creating and I think you will understand your issue.

Inputting a value and its negative for the isovalue divides space into 3 volumes - that inside the wall, that outside, and the volume of the wall itself.

Increasing that value increases the thickness of the wall, but at a certain point the wall is so thick that the spaces either side are no longer continuous labyrinths, but instead separate closed voids.

image
image1092×505 137 KB

If you want to simply divide space into 2 volumes, one solid and one void then you should only input a single iso value.

image
image915×522 71 KB

6

I tried this, waht you told me. But I got cell with full inside volume and this is wrong. Look at my screen. First what Rhino genetered and second what I need to create.

neovius.pgn
neovius.pgn1353×693 64.9 KB
(This is sectional view. So I need 40% neovius structure with hole inside)

Is the way how to generate Neovius structure with 40% volume density as in my screenshoot ?
Or I am doing something wrong ?

Thank you

7

Yes, if you want completely enclosed voids in a single mesh, you’ll need to treat them separately in the boolean step.

9

Please, I am noob :frowning: Can you send me your file where it is already done? I can pay you for this, if you want. But i really do not understand this… For first english language is not my mother language and second I do not have experience with CAD…

10

Please, can you help me ?