How to make a Revolute joint between two componennts at a certain distance?

[r.a.matveev]

Let's say I have two components. Each component has it's own rotation axis. Am I able to join these two objects at a certain distance between axises?

So at the end both components should be able to rotate around their axisses AND second component should be able to rotate around the first one (like our Earth do).

The only thing I was able to do is to put an ordinary Revolute joint with distance. But in this case the second component can not rotate around its own axis separately (as our Moon do).

So how can I assemble (join)  Sun and Earth in Fusion 360? :)))

[etfrench]

Try this:

• Make four spheres in separate componets: One Sun, one Sun core, one Earth, one Earth core.  Use one sketch with multiple diameter concentric circles (Use the joints to position the components).  Use the Revolve command to create each component.
• Make a rigid joint between the Sun and the Earth the Earth core.
• Make a revolute joint between the Sun and the Sun core.
• Make a revolute joint between the Earth and the Earth core.

Do a motion study.

[r.a.matveev]

I thougt of puting additional components. But for me it looks weird. Is there any better way?

[etfrench]

No, there is no better way.  Simply hide the cores to un-wierd the look 😁

[SaeedHamza]

Actually it can be done in a simple way

First, create a sketch with the main root activated ( main root = the main component in the browser ) so that you can use joint origins in place for each component, because if you create a joint origin using the component itself, the join origin will appear inside of the used component browser, so it won't work.

Second, apply joint origins to that created sketch, which in this case as i mentioned, these joint origins won't be a part of any sub-component.

Then, apply a joint command on the 1st component (earth), and an As-Built Joint on the second one (moon).

And in the end, use a motion link to specify how fast each component rotate when you animate the model.

Here is a file with the steps i mentioned applied.

[r.a.matveev]

If I've got your idea right, you proposed to use sketch as a links between objects?

I created the sketch in the root of the project with needed links. And the sketch itself animated properly!

And even more: I was able to join a component to a sketch vertex.

However, component can be moved among the joint only. I can't make any movement to the sketch by moving component joined to sketch.

Did I understand everything right?

[davebYYPCU]

You need 3 components, the origin, (File default)

the sketch and

the block.

The sketch revolves around the origin.

The block revolves around the sketch endpoint. (done)

Might help....

[SaeedHamza]

@davebYYPCU  That's assuming he has only 1 component to move, but adding another component to this as an Earth/Moon example, it would need more to it than that

@r.a.matveev When I replied above, I didn't notice you wanted the center component (Earth) to move around it's axis as well, it's still can be applied, but a bit more complicated

Attached you'll see a video of a Model Animation, also .f3d file to check everything

[r.a.matveev]

Thank you, @SaeedHamza for your advizes and for the model you've provided.

I checked it and see that it has only one degree of freedom. Is that correct? So if a move "Earth" it turns around his axis accordingly and the "Sun" as well.

I'd like to have 3 degrees:

1) Rotation of the "Sun" around its axis

2) Rotation of the "Earth" around its axis

3) Rotation of the "Earth" around the "Sun".

[SaeedHamza]

@r.a.matveev  From what I see, what I attached is exactly what you are talking about, 1 rotation around the each component's axis, that's 2 rotations, and the rotation of the earth around the sun ... these are the 3 movements, so i need to ask, what exactly do you mean by one degree freedom???

[r.a.matveev]

@SaeedHamza degree of freedom is a number of variables of the system. I made the model I wanted with two additional components: link and basement.

This system has 3 degrees of freedom.

The only thig I don't like in this model - it has two excess components.

[SaeedHamza]

@r.a.matveev  I believe that you missed an important thing in what i mentioned so far, and that is Motion Link.

Here, I attached the same file you attached in your last reply, but I edited it so that it has Motion Links applied to it, so try the command "Animate Model" to see that it's working.

You can see it in the timeline as 2 motion link icons, so take a look at them carefully to understand the need for 2 motion links in this to make it work.

[etfrench]

This meets your criteria 😀

[r.a.matveev]

@SaeedHamza , I see that you took my model and added motion links between joints. Is that correct?

So I see that you made my model only 1 degree of freedon again. But I need 3.

As I said before I need it so "Sun" and "Earth" could rotate independently. And "Earth" could spin around the "Sun" independently as well.

So the model I uploaded earlier is exactly what I need except the thing that I have two excess components: Basement and Link.

So the question is: can I do the same thing without both: Basement and Link?

Disclaimer: English is not my native language so I admit that some of my points can not be very clear for the community and in the same time I can miss something.

[r.a.matveev]

@etfrench , it looks like it is! Can I take a look at the file?

[etfrench]

Unfortunately, I've already deleted it.

It had four revolute joints:

1.      Earth to earth core
2.      Sun to sun core
3.      Earth core to base (Joint offset in X, Y, or Z direction)
4.      Sun core to base

And two motion links (IIRC, you may need to experiment here):

1.      Between #1 and #3
2.      Between #3 and #4 

Notes:

• Joints #1 and #2 can revolve around any axis, but this needs to be set before creating the motion links.
• Joint origins can be in hidden bodies or sketches. 
• With spheres, the center is automatically selected for the joint origin.  Other shapes can have more than one location for joint origins.
• The sun, sun core, and base origins are coincident.

[SaeedHamza]

Judging from @etfrench  attached video, by 1 degree you mean rotating around only 1 axis and you need the earth to rotate around the sun around x,y and z axis? also each has it's own rotation direction?

[r.a.matveev]

@SaeedHamza "degree of freedom" is a little bit different story: it can be consider as a number of scalar variables describibing the system.

So if object can rotate around any of three axises - this object has 3 degrees of freedom (X angle, Y angle and Z angle).

In my case I'd like to have 3 degrees of freedom:

1) Rotation of the Earth around its Z axis

2) Rotation of the Sun around its Z axis

3) Rotation of the Earth around Sun's Z axis

[LeonardoBN · Accepted solution]

I'm not sure if I forgot some premisses, but i tried to make some joints here; even not using them very often: