Slider Joint between Assemblies

[dmBRK4A]

Hi All,

I'm relatively new in Fusion 360. Actually I have a problem to apply a slider joint between two assemblies. After applying the slider joint the two assemblies are fixed together, no sliding. When using the as built slider joint the assemblies are moving free towards the other.

In the particular assemblies I tried both, using fixed joints and rigid group. No difference.

After some assessments I figured out that it is possible to use the slider joint between a component including just one body and an assembly. But as soon as I use two assemlies it does not work.

Is it even possible to use slider joints between two assemblies or do I make any mistake?

Thanks a lot for help!

[sanket223.patil]

Can you share the model .

[dmBRK4A]

Thanks for your quick reply!

Here is the link to the model:

https://a360.co/2OxXK0Q

[jeff_strater · Accepted solution]

This is actually a fairly complex concept in Fusion - joints are between components, and all assemblies in Fusion are "flexible" assemblies.  That is, an assembly has its own coordinate system that is independent of any child components in that assembly.

What you have created is a joint between assemblies.  That joint behaves as defined, meaning the assemblies' coordinate systems are related via the slider joint.  You can see this if you turn on the assembly's origin.  Even though all the components inside that assembly are correctly related to each other in a rigid group, that joint really does not refer to any of those components.  They are still free to move independently of the assembly itself.

Instead, if you create the joint between components in the assembly, it works as you'd expect.  See the screencast below.  Sorry, no audio (in a hotel room early in the morning, didn't want to wake the family...).

I understand that this is not intuitive.  This behavior is a side-effect, though, of having completely flexible assemblies, which we decided at the time was more useful than having rigid assemblies.

screencast:

[dmBRK4A]

Hi Jeff,

thank you very much for your effort to explain the functionality to me. I need to put some more thoughts in the evaluation of the principle but basically I understand your description.

Again, thanks alot!

BR