how to create a rounded ribbon-zipper line like this ...?

[Matthew A]

Hi there — stumped as to how to create this lovely mirrored line — original logo 1967 (Peter Megert) — any tips much appreciated! Im thinking I might need to connect circles at their tangents...

[Monika Gause]

If you put circles into it, then you see a couple of things: 

The black circle is larger

The circles do not meet perfectly, but it was adjusted.

So I would start with circles, then cut them and stick the parts together.

Build just the part bwtween the 2 green lines. Then reflect to build the rest.

Snapping circles or any curves precise together in Illustrator is a pain in the rear. The plugin Colliderscribe is a great help, but comes at a cost.

[Matthew A]

thanks Monica... I use Astute graphics for their halftone tool, so I think I have ColliderScribe — will try it 🙂

[Monika Gause]

Then of course you have ColliderScribe. Lucky you!

https://youtu.be/EoRQagiRUzU

[Matthew A]

Very nice — now I need to be able to add a point exactly where the objects touch!!

ColliderScribe gives me a lovely pink dot where they touch, but not means to cut there, at least I dont think so...?

[Monika Gause]

The pink dot just tells you that the objects kiss each other. It won't automatically cut there or create anchors. You could use the shapebuilder tool or live paint, whatever is appropriate for your workflow.

[Matthew A]

I think Im being dumb, I cant figure out how to divide where they meet! Have a look at this fiel if you have a second, perhaps theres something I'm missing...

[Matthew A]

heres the illustrator file...

https://www.dropbox.com/t/Z8kEYyt82AvUv0ah

[Monika Gause · Accepted solution]

You're right. I can't get it to work either. It should work, but it doesn't.

What will work though is when you use a helpter object and unite the shapes. Draw a rectangle around it. What's important: the top circle doesn't kiss the second one. You have to check the gap detection in the options.

https://youtu.be/ev0jIZHy57w 

[Matthew A]

Genius! So good, that works a treat, thanks so much!