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I'm trying to create stackable sieves for 3D printing with different mesh hole sizes.

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Example:

  1. One grid unit (the hole size) equals 0.250 mm to 1.5 mm. How can I calculate / create the grid units (the hole sizes) to be a given / exact size?

    I was attempting to use this: How to project a grid onto a circle/torus using geometry nodes?

  2. The other issue is with using the scale node not being accurate enough and the smaller I go, the more holes are not filled.

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An area that is too large becomes solid instead of filling with holes when the scale is reduced.

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See blender file below:

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  • $\begingroup$ Should the ratio between hole size and the solid part always remain the same here, or do the solid parts have a fixed thickness? $\endgroup$
    – quellenform
    Nov 1, 2023 at 8:59
  • $\begingroup$ @quellenform The solid parts have a fixed thickness $\endgroup$
    – Rick T
    Nov 1, 2023 at 11:16
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    $\begingroup$ Thanks for the info! ...knowing you and your 3D printing, I figured as much! (See answer) ;-) $\endgroup$
    – quellenform
    Nov 1, 2023 at 11:28

2 Answers 2

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In this case, the current construction makes it difficult to create with precise specifications for a hole size (and the distance between the holes), since the scaling always depends on the current size of the face and can only be controlled with $0-1$.

Therefore I would build everything differently, and work directly with a cylinder as a base and cubes, which are instantiated at the faces of a grid.

The calculation of the grid is easier this way, because you only need the following values:

  • Diameter of the sieve
  • Diameter of a hole
  • Distance between the holes
  • Height of the sieve

By dynamically calculating the size of the grid as a function of hole size + hole spacing so that they fit the size of the sieve, you can create the base grid.

Assuming the hole size is $h$, the hole spacing is $s$, and the diameter of the sieve is $d$, the formula for calculating the grid size should look like this:

$grid size =(h+s) * \lceil{\frac{d}{(h+s)}}\rceil$

In this case, I'm using the faces as points for instantiation, so here I'm also checking to see if their positions are within the radius of the sieve and then using only those points.

And if you put it in a node tree, it looks like this:

enter image description here


(Blender 3.6+)

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Instead of scaling, you should increase the number of holes. It comes from grid resolution:

enter image description here

enter image description here

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  • $\begingroup$ Thanks but how does this make the grid units (the size of the holes) a given size? / Making different size sieve meshes using geometry nodes? $\endgroup$
    – Rick T
    Nov 1, 2023 at 0:21
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    $\begingroup$ you have a grid with size 40x40, so each face has size 40/(n-1) (where n is the number of vertices). Then you scale each face so that the resulted size is (40/(n-1)) * scale $\endgroup$
    – Crantisz
    Nov 1, 2023 at 11:26

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