6 bar linkage

I’m somewhat new to Bongo, but I think I have some of the basic concepts.
I’m trying to animate a 6 bar linkage.

I have looked at other linkage models, but they seem to be different as they don’t have to connect back to themselves.

Sorry forgot to upload my model here:
Bongo Hinge.3dm (1.1 MB)

Also a video of how it works. I made this with a software called Linkage.

Hi Robin,

Did you watch this one: The scissor arm: the conception of an IK chain in Bongo 2.0 - YouTube?

It has the same basic topology.


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Yes, I did actually, but I will take another look at it.

I did try to set it up like this one originally, but i didn’t know how to attach the final joint on both ends.

From all the videos I’ve watched Bongo’s inverse kinematics chains only work with joints in a sequence and some sort of goal at the end.

So I guess this kind of linkage isn’t possible since it has to connect back to itself.
(Correct me if I’m wrong).

I did find a workaround by keyframing the positions of the end plate, problem being the transformations between keyframes are not really accurate, but probably good enough for my purposes.

Hi Robin,

You can model your linkage in Bongo:

There are several considerations. Firstly the choice of IK chains matters in this case. Joining the moving platform at its right end works, at its left end doesn’t (I guess because you are trying to push a nearly straight joint). Secondly, I’ve opted to drive the long middle bar, not the bottom one. Thirdly, there are some additional “axles” in my model.

Bongo Hinge Geometry.3dm (87.6 KB)


Sorry, should have added that at one end you have the hinge, at the other end you have the constraint (to the second linkage arm). I found it necessary to extend each chain with an “axle” and constrain one axle to the other - if I constrained the platform directly to the arm, Bongo flipped pieces out of position (no idea why).


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Hey thanks Jeremy5!
Hero status achieved!