Connect a Rigid Body to a Rigid body

[bear-ride]

Hey, I'm currently trying to recreate a keychain in c4d. I'm also planning on animating it.

This is my setup so far:

A ring (with collider tag)
A chain (with a rigid body tag)
Everything works so far so good.

Now I'm trying to add a object (with a rigid body) onto the chain. So far I have found no way to make this work. Its also group.

https://drive.google.com/file/d/1vCD66wwWucFW088ZGnV_T5qhqfmF0MgW/view?usp=sharing

Does anyone know how to make this work, or has a video that he could send me?

Best
Fabian!

[Dr. Sassi]

Hi Fabian,

Does this file come close to your setup? (Since we have two Rigid Body tags, I'm not clear with one you like to use. (Bullet or Simulation)

Example
CV4_2026_drs_25_SIcn_01.c4d

I have added a Camera.Spy, so it is easier to see that it is stable.

Let me know what this setup does not showcase, and I am happy to have a look into it.

If you can share the file, please as a c4d file and smaller than 1MB. If larger, please not zipped (no RAR either, etc) and only Dropbox, WeTransfer, Google, Apple, or Adobe Cloud services. Please paste the full URL as text (No HTML wrapper). Sorry for the long instructions, but security first.

All the best

P.S.: just in case
https://help.maxon.net/c4d/2026/en-us/Default.htm#html/DYNCONSTRAINTOBJECT.html?TocPath=Simulate%2520Menu%257CThe%2520Simulation%2520System%257CConnector%257C_____0

[bear-ride]

@Dr-Sassi Thanks for the quick reply, I uploaded the project to my drive: https://drive.google.com/drive/folders/1hoppkp4Li50jNuDLZ5aUJbVlrkrkWaCN?usp=sharing

Your project seems like what I need, I just dont understand it (yet). Thanks for the article, checking it out right now!

Best
Fabian

[Dr. Sassi]

Hi Fabian,

Thanks for the file.

Your image didn't show how the chain is connected, the file helps here.

The objects in your scene have a very high resolution for the mesh, which requires a lot of computing power. The Interpolation points of the Splines define the resulting mesh; lowering them might not directly lower the render quality. I made them editable (pressing the C key), to be faster (I don't have a super-fast computer).

I have used these lower-density objects to set this up, and cached the setup then.
When it was fully cached, I added the Key-Chain-Tag in its full resolution to it.
I have marked the objects used in the Simulation and the ones later added with different layer colors.

A few settings needed to be adjusted
Scene Scale, in the
Attribute Manager> Scene> Simulation> Scene> Scene Scale
and
the amount of calculations
Attribute Manager> Scene> Simulation> Simulation> Simulation> Substeps

Think of a moving object (pulled by gravity and inertia). It has a tiny search radius, which is the distance to explore if there is an object to collide with or not. If the "speed" of the objects is low, it will more often find a collision object in its search radius. If the speed is too high, the Object to collide with is too far away, and during the next calculation, already inside or even behind the Object. The Steps allow for calculating more often and recognizing a collision more often, and can react as intended.
To have these Steps always high means slower calculations, to have them too low, missing the "action".

Note: Between ring and first Chain element, there is very little space to explore a collision. Which requires a larger step number, just forced by design.

In the Rigid Tags, I typically set them to Both Sides, and the Collision shapes to Triangle.
The Auto option for the Collision shape is perhaps working for some, but not for any shape.

The Object I used for the key chain plate was reduced in the Remesher; the target here was a rough shape that would allow for a similar collision shape, but is in no way anything for rendering.

Here is your file back:
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20251104_CV4_2026_drs_25_SIkc_01.c4d.zip

Let me know if there are any questions about this process. I'm happy to look into it.

Enjoy