How to model an eighth of a sphere?

[davidcampbell]

Hi,

I need to create the molecular model shown in the image. I’m finding it really difficult to achieve a good result for the spheres. I need the curved surfaces to be smooth but with sharp edges where they meet the flat sides. Any suggestions on how to do this? Any help would be much appreciated.

Cheers,

David

[blndrusr]

I would create a UV Sphere, delete unneeded vertices (7/8), create missing faces to close it, and mirror in all 3 axes.
.

[davidcampbell]

That’s great. I had tried something along those lines previously but ran into problems when trying to achieve smooth shading on the curved surfaces whilst keeping the sharp edges. Can I ask how you achieve that? Are the flat surfaces of the sphere a single face? If I add smooth shading or subdivision I get something like this…

or this…

Thanks so much for your help.

[davidcampbell]

This is how it looks without trying to smooth it out…

[jerzygorskiart (Jerzy Górski)]

you can use edge creases or just add split edge modifier before subdivision

[Mohammed_Terry (Mohammed El-Tairy)]

do you mean that you want achieve hard edges while using subdivision surface modifier ?!

[blndrusr]

Turn the Shade Smooth On, go to Object Data and turn Auto Smooth On.

[Mohammed_Terry (Mohammed El-Tairy)]

if what i understand right so here is the steps i used
first i made uv sphere smooth it used 3 array modifiers
then subdivide them

then created cube and used boolean modifier with intersect opereation

then deleted the cube

hope that what you mean and sorry if i misunderstand

[davidcampbell]

Thanks Jerzy, edge creases worked great!

[davidcampbell]

Got it! Thanks again for your help

[davidcampbell]

Hi Mohammed,

That’s exactly what I wanted to achieve. Looks great. Turns out there’s a few ways to do what I wanted!

Thanks!

[Piotr_Adamowicz]

Oh come on people. Booleans? For a sphere? Where’s your self respect?

Use proper topology to achieve smooth spheres without artifacts:

sphere_topo.blend (119.0 KB)

[davidcampbell]

Thanks for your help Piotr and for supplying the blend file as well…