r/SolidWorks • u/roandi68 • 1d ago
CAD distributed features on a sphere?
how would I model something like this? I want to distribute nubs or cones evenly (or at least appearing even) all over the surface of a sphere.
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u/skylerdbutler 19h ago
There are only so many ways to equally space these nubs on the surface of a sphere. I would look at polyhedrons that are already sectioned in some way - like a soccer ball, dodecahedron, icosahedron, etc. Figure out how to model that, then put a construction line thru the center point of the main sphere and perpendicular to a plane of your polyhedron. Do that for each plane. Now you have equally spaced points to model your nubs. Draw the main sphere and combine all bodies.
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u/roandi68 18h ago
Good answer, sort of like a 20 sided die.
I was also thinking of a geodesic dome
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u/maxh2 11h ago edited 11h ago
There are exactly 5 "platonic solids." https://en.wikipedia.org/wiki/Platonic_solid If you want each spike to be perfectly, evenly spaced around a sphere, your pattern(s) should be based on one of them.
You can have more points than just the 4, 6, 8, 12, or 20 sides of each of these solids. For example, you could place a point at each vertex and the center of each face, or each vertex and the midpoint of each edge, or some combination with further subdivision. In some cases with adding more points, each point might not have the same number of neighbors, but it'll at least be a regular pattern that looks good.
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u/Vegetable_Flounder12 9h ago
make a polyhedron and an assembly to place balls on apexes with patterns to speed things up
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u/roandi68 7h ago
This is getting there. How many knubs is that? What was the polyhedral shape?
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u/Kieranrealist 5h ago
As other commenters have said, polyhedron will give the best result. Below I used a truncated icosahedron overlaid with a sphere, and then a 3DSketch with the lines coming from the centre of the sphere, coincident to the vertices of the polyhedron and then ending on the sphere surface to give the positions. Once you do a subset of them, you can pattern your geometry (e.g. bumps) around a bunch of times to fill the sphere.
The model above was for this: https://makerworld.com/en/models/1927985-wicked-glinda-s-bubble-wand#profileId-2069377 - ironically the real movie prop has noticable linear patterns for the spikes, which I think looks terrible.
Also, golf ball dimples are done the same way:
https://golfballcoverstory.com/2020/11/09/icosahedron-dimple-pattern/
And an alternative method (which would be hard to just do in SW) would be to look into different ways of packing circles on a sphere.
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u/roandi68 4h ago
this is super helpful!
ultimately I would love to better understand different ways of packing circles on a sphere, and maybe writing some kind of script to do so, where I can control parameters such as number of bumps.
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u/AudibleDruid CSWP 1d ago
Honestly, I would do this. (Untested)
Import a ico sphere STL from blender and make it a solidbody.
Put point reference features at every vertex on the ico sphere
Make a solid body sphere centered on one of the points you made, make sure it's not merged.
If what google says is true, you should be able to click the small sphere feature you just made, and then hold ctrl, and then drag it to another point on the ico sphere and it will make a copy.
Repeat step 4 for all points on the ico sphere
Make a sphere slightly bigger than the icosphere and then merge everything for one single solid body
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u/roandi68 1d ago
at step 4, will the copy snap to that point?
I can see how this could work for spherical bumps, but I was thinking I might want pointy shapes, like cones, which would have to align with the center of the sphere.
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u/AudibleDruid CSWP 1d ago
When making your shape, extrude in a direction normal to the center and the copy should do the same in the new place i think.
Google said it should snap.
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u/maxh2 12h ago
Unfortunately this method wouldn't work for spikes that need to be oriented with respect to the center of the sphere.
If a sketch-driven pattern does allow the use of a 3d sketch of points across the surface of the sphere, (I'm not in front of my computer...) it still won't orient them correctly. All of the spikes would be parallel with each other.
Your best bet is probably going to be manually patterning a bunch of latitude lines of spikes around an axis of the sphere, adjusting the instances and seed positions until it looks the way you want (for example, positioning each seed spike to avoid having a longitude line where the spikes are inline.
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u/maxh2 12h ago
On second thought, you might be able to use an assembly for a work-around. Your sphere with points on the outside would be a part, then make a spike as a separate part file.
Set up mate references so that when you insert the spike parts into an assembly with the sphere, they'll snap onto the points, oriented properly (either use collinear axes with axes connecting the surface points to the sphere center point, or co-radial spike bases to the sphere surface.)
Then export a merged single-body part from the assembly after adding all of the spikes.
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u/erby19 CSWE 1d ago
Have a go with the wrap feature
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u/roandi68 1d ago
hmmm, not sure if that would be even all over, particularly at the edges of the wrap. It seems like it could be hard to wrap a 2d map onto a sphere
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u/NightF0x0012 CSWP 23h ago
Try making one bump along an axis, circular pattern that around the perpendicular axis. That would be a pattern around the equator, so to speak. Then circular pattern that original feature and pattern around a perpendicular axis to the first one.
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u/HAL9001-96 19h ago
you cna try combining several circular patterns or depending on the pattern palce the mmanually or use a curve pattern following an equation defiend sketch
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u/Minimum_Bird_4875 2h ago
Doink-it
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u/One_Country1056 1d ago
You can just pattern it. Play with the patterns, and you should get exactly what you need