Help with Joint Warning after Breaking Link

[tookemtoni]

Hello There,

I'm having trouble diagnosing how to avoid this warning.

Must have something to do with how the components or joints are set up.  I've tried a couple different versions but still get the same warning.  I've attached a demo video and link to download the file https://a360.co/3OXjy7v.

Warning: ImplicitJointOrigin5(CupToDoor_Top)
<b>2 Reference Failures</b><br/>The model is using cached geometry to solve. Please reselect reference geometry for failed features in the timeline.

[Drewpan]

Hi,

Have you tried doing an edit on the item in the timeline and just accepting it without a change? The warning says

it is using cached geometry and doing the above will let the software recalculate and replace whatever is in the cache.

Start doing this from the FIRST yellow item on the timeline and often items downstream fix themselves too.

This does not always work but often it does. Fusion is a bit fickle about what it re-calculates and where it recalculates

the data from. Sometimes it uses what is actually there and sometimes it uses what it has in the cache, it is written

that way for performance reasons.

Cheers

Andrew

[tookemtoni]

thanks @Drewpan,

Why I am getting this warning? How can I model this differently to avoid this warning or is this a bug?

[Drewpan]

Hi,

The issue is that you are breaking a link so that Fusion does not have a "real" thing to look at anymore. It has to

recalculate from what it has because the link data is not accessible. Remember that one reason the link exists

is so that changes made to the linked component are updated in the new design when you refresh the data. If

Fusion cannot see the component because you removed the link you have to tell it what to use instead.

Breaking the link means that the component will not be updated anymore. Once you break the link and tell Fusion

what it is to use from now on it should work. It is still possible to not update and have problems but if it can work

it out it will.

I don't think it is possible to break a link without this happening sometimes. It depends on what the original

component was and how complex it is in most cases. Complex parts can have a lot of things Fusion has to

calculate and so are more likely to break when you break a link. One of the reasons it is recommended to fix red

and yellow timeline issues is that they have a habit of compounding and cause all sorts of problems in unexpected

places which are sometime not obvious when you initially do them. Many a project has been restarted because it is

easier to begin from scratch than to try to fix the problems because these issues have been ignored and not fixed

earlier.

Cheers

Andrew

[tookemtoni]

@Drewpan, Thank you for your explanation but I really want to believe that there is another way to do this without getting this warning or there is a limitation in Fusion.

In terms of the design intent, I am using this  “insert - brake link method” as a kind of “paste new” from other designs. 

I been using this method with around 10 other design with fail. 🌞 So I was a bit surprised that this design didn't work.

As far as I know the “insert - brake link method” is the only way to copy designs into other designs.

[Drewpan]

Hi,

The reason the link is there is so that Fusion can update to the latest version when you refresh. When you break

the link it cannot do that. This should not be an ongoing thing you have to do. When you break the link you may

have to do it once and that's it. After you have updated the local version to the new design it should then work as

expected. You will not have to keep doing it every time you work on a design, just when you break the link the first

time.

This behaviour occurs because Fusion calculates a lot of stuff on the fly to display it. It relies on cached data to

update faster. In effect you are creating a local cache of data after you break the link, then it works fine.

The developers have been hammering performance for a while now, and rightly so, Like most engineering,

even software engineering, there is always a tradeoff for certain things. Cache data is saved with the original

design, when you break the link Fusion creates a new cache of data but sometimes cannot work stuff out and

needs a nudge. Once you have told it what it needs it works after that.

Andrew

[TrippyLighting]

@Drewpan, what in the world are you talking about?

The inserted assembly is very simple and fully self-contained. This should NOT be happening and is a bug. End of Story!

@Phil.E

[Phil.E]

@TrippyLighting The problem comes when the break link action makes the model compute. For some reason, the combine feature towards the end produces new edge/face IDs and the Joints don't know where to go. If you edit the joints you can reselect the edges, after breaking link.

Looking closer at the model, you could replace the last two rigid joints with As Built joints. These are stable because they don't rely on the edge/face ID created by the combine command.

Or, since your design intent is to end up with a fully rigid, open hinge, that doesn't move at all, just make the hinge a rigid group in the original design. Why does the inserted hinge have motion that requires you to constrain the motion when you insert this part? Save all those downstream clicks and make the hinge rigid, rather than applying multiple joints to do the same thing later.

So yes, there is a bug. It's the Combine command unable to retain the edge/face ID that the Joint Origin is looking for, on the door component. IMO this is easy to work around, and the workaround might be a preferred workflow anyway. I'll log a ticket for this issue with Combine/break link. (FUS-150317)

[TrippyLighting]

@Phil.E Thanks!