Hoberman joints

[tripleSheva]

I created a two-dimensional Hoberman mechanism, and I'm trying to create the relevant joints so that when I pull/push on one of the blades, the rest will pull and push, contracting/extracting the mechanism's diameter, like a Hoberman sphere would.

In the attached I reverted the circular pattern and the different attempts I tried with joints, to make it easier for someone to jump in and understand the design. My idea is to use Circular Pattern to duplicate the Blade Couple component by bladeCount, and then create the joints. I created one As-built Joint for the couple, but I'm not sure if that's good or not, or if there's a way to make joints so that they auto-connect when creating the pattern duplicates.

[jhackney1972]

If it helps, you can circular pattern you current sub-assembly and maintain the single joint, if you pattern the Blade Couple sub-assembly using Component as your object type.  The joint in the sub-assembly will be maintained but each sub-assembly will be free to move and must be joined, or one component grounded to use the joint.

See the attached model

[tripleSheva]

Thanks John. I reached this stage as well. My goal, however, is to have all instances react to the movement of a single blade. See this image, for reference; When manipulating a single blade's joint, it affects the entire mechanism. The red line represents a single blade.

[jhackney1972]

I had another idea on how to create the assembly you are looking for using the Duplicate with Joints command.  You have to pay close attention to the process as it is easy to get mixed up on the picks.  I would advise removing your original Joint Limits and your Ground to Parent on the first sub-assembly before beginning. If you try and move the assembly, I have attached, I would recommend you select one of the large pivot joints and use the "Drive Joint" command for control.  The video will show the adding of one sub-assembly to the chain. 

[tripleSheva]

Thanks! Your solution sounded similar to my manual approach of "Circular pattern > Joint > Select points ; Rinse and repeat", so I just did it manually. 😐

However, after revising the sketches a bit, I had to fix all the joints, so now I have an issue that I don't quite understand how to diagnose and resolve: The last two joints won't "connect", and if I navigate the timeline to (or past) them, the first two joints in the timeline are painted in red on the components on the stage. What am I missing?

[tripleSheva · Accepted solution]

To answer my own question, I ended going with Circular Pattern, then manually created revolution joints between each pair. As for the red joints, I found that after editing the underlying sketches and re-linking the joints, I miss-linked one of the joints earlier down the timeline. I learned that by inspecting the Joints folder in the explorer I can see more easily which joints have issues, and I was able to resolve the issue.

Everything now works as expected. I just wish there was a more reliable way to do this in Fusion.