Surface problem- making a crown

Hi! I hope someone have time to help me now
I have a crown that I’m trying to draw, a little jewellery charm.
What bothers me is, the middle (The red arrows point at the problem)…
I just can’t figure how to make it nice like the other components… Smooth and rounded

In the picture, the Top View- I have my curves, so you know how it looks like.
They way I made it; I made profile curves and oriented them on the rails, and then Sweep2.

How can I solve the problem in the middle?Crown2.3dm (1.0 MB)

How did you make the middle part?

It is much easier to diagnose problems if the .3dm file with the model is included in your post. You can upload the file by clicking on the vertical arrow icon in the row of icons above where you type posts.

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Crown2.3dm (1.0 MB)

I have marked the layers:


Thank you davidcockey, that you want to take a look
I appreciate it very much :smiley:

What do you want the middle to look like? What shape do you want the center part to be? Can you sketch it? Do you want the sides to flow smoothly into a center part?

The main idea here in my opinion is to separate the parts, so you wont have to have a long part like you had.
and solve each problem by its own since I can’t figure out a way to that shape in one shot.

So I’ve done the bottom part with sweep2rail and the upper part with NetworkSrf.
you could play more with the lines of the network and get even better results.
eventually you could try to “match” the surfaces or to “merge” them to get a more fluid result.

Good Luck :slight_smile:

Crown2-Roy.3dm (1.3 MB)

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I think you need to sketch a bit more on how you want it to look then it’s easier to CAD it, but here is a good tutorial on how to make a Y branch, which the middle parts is.


Hi @davidcockey
I hope you can see the picture I have loaded, and how I wish to shape the center part. I want it rounded like the others and flow nicely out with the other components

Hi Roy
Thank you for illustrating an approach for this, and taking your time to help me :smile:

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Thank you jjn :smiley:
That was a really good video :+1:

Go watch this video, and then bookmark it. You’ll be coming back, often.

Pound for pound that’s the best Rhino surfacing tutorial for this type of work on the web.




No offence, but that is a good tutorial to make a crappy Y-branch.
It doesn’t even look good in shaded mode…

Cheers, Norbert

Thanks for posting the video by Brian James. It can also be found at Rhino Tech Tips: Modeling a bubble R

Some other McNeel videos are at

No offence, but can you please contribute with something to the discussion?

For what it is worth, if you want to keep the hard-edged font design and not bubble-ize it quite so much, I’d put the surfaces together something like in the attached file.

R-HardBubble.3dm (624.8 KB)



I already did by pointing out that the video you posted is an example of bad modeling technique.
(and this is visible even to the naked eye, no zebra projection needed)
Anyone interested in learning good modeling practices might appreciate this information.

Cheers, Norbert

OK, you’re right, looked through the tutorial more detailed this time and I agree it was bad. My apologies.
Just looked for a Y branch tutorial and assumed they knew how to produce good surfaces.

Hi. Drawing such shapes fairly often. After the implementation of MoveUNV in Rhino for Mac I have finally found a good approach to deal with it.

See screenshot. By using this technique you have full control of your required shape and are not dependant on the build in matching tools.

If there is interest I could try and make a tutorial of it when I find the time. Maybe the cp layout can already give you an idea.


I’d certainly like to see a tutorial. Perhaps ahead of a full blown tutorial could you in a couple sentences convey the basic workflow?



This is how I would handle this topology. I roughed it out quickly. To get it perfect would require me to rebuild all your surfaces as beziers.