DESIGN CHALLENGE x2: Creation of uniform irregular holes on solid via .svg

[Anonymous]

Greetings Fusion360 Community.

I am currently working on designing and 3D printing an diatom (a single celled alga) - specifically, a genus called 'Skeletonema'. No particular species as incorporating species level identification morphology would be insane! Picture as follows:

To give you an idea of scale in reality, one of those 'branches' to the half way 'joint' is about 4 um - of course, im planning to make it a LOT larger. This image is taken by a scanning electron microscope.

The great challenge of this project is to create a 'uniform' pattern of holes but give each one a variability/irregularity allowing them to look organic. To generate this hole/pore pattern I am using Inkscape (a free vector drawing program) to create the desired uniform pattern (using circles), selecting these circles, then use those circle-selections to generate a voronoi pattern (Menu: Extensions-Generate from Path-Voronoi Diagram). For reference, this URL gives a basic idea of the creation of this pattern when following Step 1 to Step 3:
http://www.instructables.com/id/Voronoï-Lamp/

My proposed method to design the solids as follows:
- For the top/inside cone: Create a cylinder, project a .svg of the hole pattern onto the TOP it, extrude-cut it away DOWN, then shape the cylinder into the shape cone I want and hollow it out.

-  For the bottom cylinder: Create another cylinder underneath, project a .svg of the hole pattern around the SIDES it, extrude-cut it away then join it up.

- The 'stalks' I will model separately (probably using cross-sections and lofting and lots of cursing).

As with my text above using Inkscape to create uniform voronoi patterns, the output is angled shapes and NOT organically round... so what im doing is selecting each edge of the voronoi cell, creating an OFFSET, EXTRUDING the offset, then using FILLET to turn it ovoid - and it works!
Its just insanely time intensive. Image as follows:

As you can see - using the .svg ive created an offset on some cells, extruded them (joining bodies), then used fillet to create organic holes from the inside edges of the offset voronoi cells (that follow the voronoi pattern).
Ive moved the body off the sketch area with the offsets for clarity.
Very time intensive... im surprised it works and im surprised it looks as good as it does also.

CHALLENGE ONE:

Is there any way to make these uniform irregular holes within Fusion360 without using .svg's, or ANY way that is less time intensive?

As for the BOTTOM cylinder (the base) of the diatom... unfortunately there is no way to project a .svg along a circle's circumference so I can extrude in (to cut) or out (to add) any .svg pattern.
So, im following the work around written up by this fellow (URL below), where you create a circle sketch, split it, go into SHEET METAL, use FLANGE, UNFOLD it, modify the sheet (in this case, the sheet would be modified using my voronoi pattern, but a rectangular one), then REFOLD it into an open-circle/arc again and join it back up.

https://www.desktopmakes.com/single-post/2017/08/29/Wrap-Text-Around-a-Cylinder-In-Fusion-360
As a test, it has turned out like this (which, for a test, isn't half bad - its a proof of concept at least...):

Doesn't look half bad.

CHALLENGE TWO:
Is there a better and/or faster way to do this?

Any feedback (other than 'that's insane', 'why would you do that' and 'give up already') would be GREATLY appreciated!! 🙂

Sincerely,

ebe

[I_Forge_KC]

Is there a reason you aren't using the Voronoi Sketch Generator tool for Fusion?

https://apps.autodesk.com/FUSION/en/Detail/Index?id=1006119760063675415&os=Win64&appLang=en

If gives the option for angular OR rounded cells. If you apply the sketch to a sheetmetal unfold and then refold, you get the (basic) shape you're looking for. 

[jodom4]

Hey ebe-a51,

You might want to try this Voronoi add-in for the pattern. https://apps.autodesk.com/FUSION/en/Detail/Index?id=1006119760063675415&appLang=en&os=Mac

[TrippyLighting]

There is no way I would attempt to do this organic model in Fusion 360, particularly not with solid modeling techniques.

This is a Sub-D model all the way! 

[PhilProcarioJr]

@Anonymous

As @TrippyLighting said there is no way I would do this with solid modeling either. First off doing this with solid modeling will make things look too uniform and actually kill the look/effect your going for.

If I were to do this in fusion and that's a very big if...then I would use T-Splines and the pipe tool for most of the work.

I can almost promise you that if you achieve what is in your picture you are going to run into performance issues in Fusion....

[Anonymous]

Cheers for your reply (to everyone so far).

Ive actually tried BOTH the free and paid voronoi plugin for Fusion360.  They work great, however, they RANDOMLY generate/place their voronoi patterns.

In the image of the diatom, you can see that although the holes are an irregular (and organic) shape, they actually follow a uniform distribution (its one identifying features for species level identifications). Because both F360 plugins place/generate their patterns randomly, they don't provide the necessary uniformity required to produce an accurate representation of the specimen.

This is why im using Inkscape to make voronoi patterns - the cells can come out in a (somewhat) uniform pattern, yet still have that randomised, organic-like geometry.

Hence the 'creation of uniform irregular holes' challenge 🙂

Other responses:

- I cant really use T-splines because I want to 3D print it. It will need to be solid.

-  @TrippyLighting What do you mean by Sub-D model?

I only really have experience (what little I have) in Fusion 360. I don't have any Blender skills or anything... so I don't think/know if using different modelling software is an option.

Cheers folks!

[TrippyLighting]

T-Splines do create solids if modeled that way !

Sub-D refers to subdivision surface modeling, a technique with very similar modeling approach to T-SPlines.

In fact I frequently import Sub-D meshes from Blender into Fusion 360 and convert them into T-SPlines and then into Solids.

The thing is that all Sub-D modeling tools I know (Blender, Houdini, MoDo) have vastly more powerful modeling tools then the T-Spline environment in Fusion 360.

Also, just FYI, Blender has a set of 3D printing tools that you won't find in Fusion 360 and people very often use Blender for 3D printing.

[Anonymous]

To be frank, I haven't done much t-spline work, some, but not much - ive been able to get away with modelling solids so far.

I don't see how using t-splines would be able to generate this pattern with less effort than using .svg templates, offsetting, extruding and filleting everything. The only pro is that ild be able to directly manipulate the mesh into the shapes im aiming to achieve?

With the complexity of irregular organic ovoids (which is what these holes would be), im guessing that it would be infact harder because of having to manipulate nodes and vectors directly??

Could you explain further so I can head off and do some research?

[TrippyLighting]

I am not suggesting to use  the T-Spline environment in Fusion 360, unless you had to machine this object.

Granted mesh modeling is not easy to learn and takes a good bit of practice, but the matter of fact is that modern mesh modelers employ are chock full of high tech algorithms and work flows and are much more innovative than the usual CAD software.

If you look at Houdini for example, while I don't have much experience with it, I am 100%certain the these organic structure of your model can be modeled fully parametric without having to create all these patterns fully manually.

I personally use Blender and for organic, stuff and for  3D printed models I would not even have to leave it as it has builtin  3D printing tools that you won't find in Fusion 360.

If your not familiar with it and don't currently have the time to learn I understand that, but I can assure you that it will be very difficult, if not impossible to create the organic look of this object with solid modeling methods.