Tentacle Vertebrae


I am on to a new/old project. I want to 3D print a tentacle.
The tentacle has a speedometer cable spine in the middle and then consists of several vertebraes in different sizes along its length.

This is a photo of a finished tentacle that I have made with the Onshape CAD programm. Now, I want to do the project with Grasshopper.

I have already created a working definition last night with which I can create the different vertebrae and also make changed as needed. (Lower part of the Grasshopper Canvas)

2021_10_30_Tentakel_V1.gh (25.4 KB)

However, I have to create the vertebraes with the definition one by one. I was wondering if there would be a way to say: ok, I know I want my tentacle to be, say 1m long and I want to have e.g. 20 vertebraes along its length with an even spacing of about 4 cm between all of them. The smallest vertebrae could have a 3 cm diameter and the next one is 0.5 cm wider in diameter and so on and so on… And then I produce all these vertebraes in one go…and when I want to make a new tentacle that is 2m long and has more or less vertebraes along its length next time, I simply put in the new values and create it.
I tried to make a definition (upper part of the grasshopper canvas), but I got completely stuck. Has anyone a suggestion how I could go about?

Best wishes and thank you for your help

2021_10_30_Tentakel_V1_reV1.gh (32.2 KB)

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Wow thank you. This is amazing. I would have never thought of using “flip curve” and “flip plane”. why is flipping them necessary here?
Your solution is exactly what I had in mind when I was asking my question. Thank you.


Hi, I am just studying your solution and with closer examintion I realized that maybe it is not 100% what I was trying to do: The scale component is applying a uniform scaling over all of the vertebrae. It makes the hole in the middle smaller or bigger, depending on how big hte vertebrae is and it also changes the 4 holes on the outside, depended on the size of the vertebrae. The round holes all have to keep their size. They are screwholes or through holes, through which I thread the control mechanism.

Do you see a chance to not scale those?

Otherwise this is a really cool solution. I love it. Thanks for sharing it with me.

Then, you can make your vertebraes(?) with variable diameters while some fixed parameters inside from the first place.

That could be easy enought for you I guess… :wink:

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I have to think about it. I thought they were “fixed”. I mean I can change them over the sliders…but only when I move to different speedometer cables, etc.
I give it a fresh thought tmw.

Thank you

I think this is what you’re trying to achieve:

Gets a bit slow if you create a lot of your “vertebrae” due to the solid boolean operations. (~12 seconds on my old computer to create 25) Not too terrible I suppose.

Vertebrae_211101a.gh (35.3 KB)

Edit: Replaced most of the solid boolean operations with curve / region operations. Faster now: ~3 seconds to create 25 vertebrae, ~11 seconds to create 100.

Vertebrae_211103b.gh (34.6 KB)


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This is so cool. I like it. and I am really happy to learn from your solution.