Multiple Joints Between Components

[johnXH8PE]

I'm trying to figure out how to constrain two components. I know how to do this type of think in SolidWorks, but I'm stumped as to how to do it in Fusion 360. Here is an image:

I currently have a planar joint to align the gray part with the blue part vertically. Now I want to constrain it in the horizontal direction so that the front face is parallel with the opening. I can't use a second planar joint because the blue edge I would want to use has draft applied, which means it's not parallel with the front face of the gray part. In SolidWorks, I could use a parallel joint between the face and a line, but I can't seem to do this with Fusion.

Here is another view where I've applied some rotation around the Z so that it's clearly not aligned correctly.

I want to be aligned correctly, and to be parametric. Any suggestions?

[jeff_strater]

I would constrain these components by applying a rigid joint between the top of the post on the blue component with the top of the hole on the gray component.  If, for some reason, that doesn't work, (because the orientation of the component is not correct), then applying two revolute joints between the hole and the post should get it oriented correctly.  You will get a warning that you are applying two joints between the same pair of components, but you can ignore that.

Jeff

[davebYYPCU]

Depends on how the Components were made, Fusion works with one joint, for position and alignment.

Can you move / align the moving part into place?  If so place it and use as built joint.

Another way is a revolve joint on one pin / socket, and set the revolve angle to the alignment.

There was another recent thread, (Aligning round plates with index hole)

You can use construction lines between socket and pins on each Component, and the using Midpoints of those lines for position, and alignment. 

Might help....

[drew]

Hi - I'm a new user here, but had ideas to share  -

In the real-life product, how will that grey part be fixed into position?

From the posts on the blue part, it looks like the grey part will mount over them, but it isn't clear from the shapes if grey will be screwed to blue or if it's glued in.

You're trying to join the two with a rigid joint, at the flat surfaces - but maybe if grey isn't glued to blue try to make it stay in position the same way as it will be held in position in the real world?

EG - That joint between the top circles of the holes in grey to the circles at the top of the posts as mentioned in the post above mine - which would mimic the real-world application of a screw.

You could get part-to-part alignment first enabling all contact, then doing one corner joined with a rotating joint then doing the opposing corner with a rigid - and forcing grey into proper orientation in the process.

Or, create a new component that is just a flat disc to use as a 'cap' that you can join to the posts on blue - again mimicking a screw's physical presence. 

Hope this isn't nutters!

[johnXH8PE]

@jeff_strater, I didn't think to use Rigid because I made an assumption about how it works that seems incorrect. To try it out, I kept the planar joint, and then added a rigid group between the gray screen and the blue body. Next I changed the position of the screen hole in the blue body. To my surprise, the screen followed to the position of the new hole. How does it know to do that? When I created the screen, I did not draw it in place, so I'm confused as to how their positions are kept together.

My goal is to make all of the positioning between components parametric. One of the things that has made this difficult is my inclusion of draft in the components, which means I can't use multiple planar joints. When using rigid group, one of my challenges is also to get the parts aligned correctly before using the rigid joint. Sure, I could carefully move the part into position, but I'd like to be precise about this. Using the Align command has it's own issues, again due to the presence of draft, as the align command seems to use the same anchors as the joint command.

[johnXH8PE]

@davebYYPCU and @drew, I can align the screen by using the pins (that also have draft) and the holes in the screen, which is what I've done. This mimics how the screen will be held in position (by melting the top of the plastic pins to hold the screen, I think--still working on that).

However, I'm wanting to understand how to do the type of alignment that I'm used to doing with SolidWorks. It sounds like I simply need to start thinking in terms of Fusion 360 joints rather than what I'm used to. One of my favorite SolidWorks joints is the Width joint, as it makes it really easy to align a part half way between to other parts. Am I correct that Fusion 360 uses a very different metaphor, and so I should stop trying to push a square peg into a round hole (or is it the other way around)?

[Anonymous]

Forget about how you do it in Solidworks - joints are very different from mates, and require a different mindset.  I would put a revolute joint between one of the pins in the blue part and one of the holes in the gray part.  At least half of the time, when you do this, Fusion will magically align the other holes and pins.  If it doesn't use AlignComponents to align one of the other pins and holes to get the correct rotation.  Finally, once the two parts are properly positioned, Lock the revolute joint to fix the parts in place.

Regards,

Ray L.

[johnXH8PE]

@Anonymous. Got it. Forget SolidWorks, accept Fusion 360. I can do that . As I mentioned above, using a planar joint plus two cylindrical joints fully constrained the two parts and worked well.

Thanks,

  -- John

[davebYYPCU]

That it is done, all good, not a solidworks user, so can't comment.

[jeff_strater]

Hi @johnXH8PE,

If that works for you, that's great.  I'm not sure I understand the purpose of the planar joint, but if you are happy with it, that is all that matters.  Usually, the fewer the joints, the better.

One important thing to know about is that Rigid Group is not parametric (well, kinda parametric, but not really).  It is not parametric in that the relationships between components is not based on geometry, it is based on position.  So, if your component change size, they could interfere with each other.

Jeff

[johnXH8PE]

@jeff_strater Here is a cross section that should help explain why I need a planar joint:

As you can see, there is a small lip in the blue part around the screen. I have the planar joint between the top of this lip and the bottom of the circuit board (at the center of the red circle). Then I use a cylindrical joint between the hole in the circuit board and the blue pin. I selected the hole first, and then the pin. I did this because the top of the pin extends above the back of the screen's circuit board. My thinking is that I'll melt it over the back of the circuit board to hold the screen in place.

BTW, I don't do this for a living--this is a hobby, so that means I'm by no means an expert at any of this. But it's fun.