Dynamic Chains and friction effects

[MFVis]

I followed a most excellent tutorial from our good friend RocketLasso on how to make a dynamic chain system. It works brilliantly (as usual for anything from Chris Schmidt). And then I got to tinkering with it Model attached.

I'm looking to make an end-state mesh that I can print (via the volume mesher). The object is to get the chains to wrap around the sphere barber-pole fashion, and when they get to the sweet spot, export current state to object and I'm on my way to the printer.

So I added a motor to the sphere, bumped up the friction on everything, and let 'er rip. Works fantastic, except that the chains slip over the surface of the sphere and in the end line up pretty much in straight longitudinal paths regardless of how I try to trick it. I even tried using an atom array to make the sphere more bumpy, but that didn't help much.

My sense is the dynamics are rock solid, but Cinema friction and real-world friction are a little different. The alternative would be to have the bottom ring and top ring rotate at different rates, and so twist the chains around the sphere, rather than use friction. But given how the chain assembly is built, I can't figure out how to get independent control of the bottom ring.

I can always rebuild the rig and start the process over, but I hope I'm just missing a simple checkbox setting, which will solve all my issues. If such a thing exists, I'm sure you'll know where to find it

Dynamic Chain.c4d

[Dr. Sassi]

Hi MFVis,

Thanks for the file.

What you see initially as a "spiral" shape is based on the shortest line between the start and end of the Chain. Then, the top part of the Chain moves to the center, which pulls the Chain as much as possible into the shortest line.
The sphere rotates fast, which allows for sliding; slower and less gravity might help a little bit. But there is always the pull from the chain elements close to the center. Then, the next element is pulled, etc. After a while, things move to be straight.
The chain surface that touches the sphere is minimal, so the friction must be extremely high.
I have tried to find some "tricks" to get it into that shape, like a friction field that is placed in the lower area of the sphere, to "suck" the energy out of the elements and bring them to stop moving. Even with extreme friction (over 100% friction and very low bounce), that looks wrong. The sphere is moving, and with that, the chains move. This movement and the forces working on it will straighten the chains. To me, that feels natural.
With a very low Gravity, all the effects are easy to see.

(The Simulation with Stickiness comes to mind.)

If you want to print it, why so much effort? Define a Spline and produce the Chain with it. Done, takes very little time, and is easily art-directable.

CV4_2024_drs_24_MOtc_01.c4d

All the best

[MFVis]

Ah! Of course. It is a physics engine after all, so it would naturally follow the rules. I was so taken with playing with the beautiful dynamics that I missed the obvious solution. Nice and simple step-wise approach with an end product of exactly the right curvature. In first iterations I attempted to use a rope tag and wrap the chain that way, but couldn't figure out how to get the links to alternate rotation - voila Formula - so that's what it's for! I am simultaneously energized by the unlimited cosmic power and demoralized by my small brain to hold it all.

The Simulation with Stickiness - would that be the one with spaghetti by Jonas Pilz?

[Dr. Sassi]

Yes, as you summarized it very well, MFVis.

Stay with the Unlimited Cosmic Power for now, and ignore any negative influences in your thinking. It will serve you better than any negative focus. (Negative focus, is that diffusion?

The Quick Tip from Jonas
https://youtu.be/S8mcZ8Nr9SI?feature=shared
would be an option to get there, as the Chains move from the outside to the inside while the sphere is rotating. This would require getting the rotation and the "moving inwards" in sync.

Enjoy your Sunday.

[MFVis]

Do you get a day off? You're always there when we need you (which is nice) but must come at a price.

[Dr. Sassi]

Very kind of you to ask, MFVis.

Yes, for the past two weeks, I had time off.
I know how it feels to be in the middle of something and miss something. I'm happy when I get a timely reply. I'm constantly learning.
In that sense, I love to be here and share what I can.

Thanks again, and enjoy!

[Dr. Sassi]

P.S.: Here is an example with extreme stickiness.

CV4_2024_drs_24_SIcs_01.c4d

Enjoy