topic Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component. in Fusion Design, Validate & Document Forum

Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 01:17:36 GMT

The behavior of a rigid joint differs depending on how the joint was created. I see this as an anomaly at best, or a bug at worst, until someone can explain the logic between the joint behavior differences. Using Joint (Rigid behavior) in case 1, and As Built Joint (Rigid behavior) in case 2. When one of the components in each case is resized, the joint relationship is maintained in case 1, but the relationship not maintained in case 2. Both joint commands are specified as "Rigid". After the resizing of one on the components, the joint is indeed rigid in both cases, but the relationship of the faces that are joined together is different. Why is this? I do not find this intuitive. Until explained I view it as illogical as well - or even a bug. Help me out here. Why this behavior difference?

I have documented the process used to demonstrate the anomalous behavior in the referenced screencast.

David

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 01:06:25 GMT

I don't see how to post the screencast URL - I keep getting "invalid HTML was found in the message body".

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 01:12:24 GMT

Maybe the screencast will show up this time.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davebYYPCU — Fri, 08 Oct 2021 02:29:44 GMT

Expected behaviour, or should I say designed to be that way.

Two different systems, and your expecting the same behaviour, would only need one system - no?

Joints work on the Component Origins, in both cases -

As Built version of the Joint system, correlates the position of both Component origins - a snap position is not requested. Change a body size has no effect on either Component Origin.

Normal Joint, correlates the component origins relative to the Joint snap Points. Snap points are requested and designated, the Joint snap points are maintained when the body parameter is changed.

Might help.....

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

jeff_strater — Fri, 08 Oct 2021 02:34:21 GMT

yes, what @davebYYPCU said is correct. This is fully expected behavior. The entire difference between Joint and As-Built Joint is that the latter does not require you to select geometry in order to create the Rigid Joint. It assumes that the components are in the correct position at the time the command is executed. So, because changing the geometry does not change that position, the As-Built Joint cannot react to that geometry change. Regular Joints, though, because you select geometry, can "track" that geometry and respond when that geometry has moved.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 04:12:09 GMT

Thanks for the replies @davebYYPCU and @jeff_strater. This is pretty non-obvious to someone transitioning to this platform, nor has it been explored in any of the training videos I have seen. I understand the differences completely now that you amplify what's going on behind the curtain so to speak. But again, as someone transitioning to F360 from other CAD environments, the behavior seems illogical and frustrating when the two approaches are both referred to as "Rigid" joints.

At a minimum, the As Built with Rigid attributes should be called something other than "Rigid" - they are not "Rigid" in the same context as a joint involving geometry relationships. I would suggest that in the As Built operation pull-down, the term "Rigid" be relabeled something like "Connected" or "Stationary" - pick something descriptive that is not "rigid". That would certainly clear up the confusion and create a meaningful distinction between the two different joint type characteristics.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 04:16:11 GMT

It may be "expected" to you, but to me it isn't expected at all given the terminology ("Rigid") is used synonymously by the two joint types. "By design" I agree with now that I understand it, but it's anything but "expected" if you're coming fresh to this platform from something like Solidworks. I submit that your use of terminology ("expected behavior") is equally baffling. "Expected" no, "By Design" yes, but poorly identified with the use of "Rigid".

See my other response post.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davebYYPCU — Fri, 08 Oct 2021 04:39:29 GMT

Sorry, Expected Behaviour was referring to Fusion, and not other systems.

As Built vs Normal, is the distinction -

Fusion does not use Mates, so how is Fusion anyway expected to be similar to others?

I forgot to mention, with all Origins visible, replay your timeline and you will see the differences in the two Joint versions.

Might help....

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 04:45:58 GMT

Yes, after your first post, I turned on the origins, and along with your description I now completely understand the differences.

"Expected behavior" is in the eye of the beholder. Coming new to Fusion, this was not at all "expected". "By design" certainly is descriptive, and I now understand the rationale behind the behavior. The term "Expected behavior" is only applicable if your viewpoint is as an established Fusion guru. One day I will get there. In the meantime, I'm trying to give feedback as to how this comes across to someone transitioning to F360 from another platform. These comments, including my suggestion to change the term "Rigid" in As Built joint pull-down, is my effort to provide constructive feedback if Autodesk is listening or interested.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

TheCADWhisperer — Fri, 08 Oct 2021 11:53:12 GMT

@davidpbest wrote:
... if you're coming fresh to this platform from something like Solidworks.

Can you Attach your SolidWorks example?

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 19:15:58 GMT

This isn't about Solidworks.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

TheCADWhisperer — Fri, 08 Oct 2021 19:58:07 GMT

You mentioned SolidWorks?

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

ercwtsnHDS — Fri, 08 Oct 2021 20:19:22 GMT

It appears as if the as-built joint is attaching to the other two components. When you select the second component for the as-built operation the rigid icon appears on the other two components. (The action is at the 3:01 mark)

That's looks to be a bug.

Can you confirm the components through the browser tree?

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davebYYPCU — Fri, 08 Oct 2021 20:47:57 GMT

What is not shown in the video, is the Origins for Document and each component.(totalling 5)

until the change of body size with the normal Joint, all Origins are overlaid.

After the changed parameter, for the normal Jointed box, that component origin has adjusted position.

So yes - in effect the other 3 components own the same component origin position as the document. The position of the joint icon in the window is insignificant for this discussion.

Might help....

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Fri, 08 Oct 2021 20:52:11 GMT

This is not about Solidworks.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

TrippyLighting — Sat, 09 Oct 2021 01:03:44 GMT

@davidpbest wrote:

I would suggest that in the As Built operation pull-down, the term "Rigid" be relabeled something like "Connected" or "Stationary" - pick something descriptive that is not "rigid". That would certainly clear up the confusion and create a meaningful distinction between the two different joint type characteristics.

There are a number of abstract concepts such as the difference between "delete" and "remove" or the "as-built joint", that do not exist in that form in other CAD systems. As such a simple relabeling does not really explain that abstraction or the behavior that you see.

In a top down design where everything is designed in place, the as built rigid joint is extremely efficient and rock-solid.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Sat, 09 Oct 2021 01:23:02 GMT

I don't really understand why people keep piling on in this thread with unrelated commentary.

My point is not about the functionality, or whether the concepts exist or do not exist in other CAD packages. My point is simply that the two joint types are labeled in such a way that someone unfamiliar with the underlying complexities of the two would assume they should behave identically.

I still maintain that using the term "Rigid" in both a Joint tool and As Built Joint tool creates the impression that the results will in fact be Rigid when they are not if the components are subsequently resized.

Calling the As Built Joint "rigid" specification something slightly different (like Stationary or something else) would clue the user into the fact that the behavior is NOT identical to "rigid" used in the other tool.

To use your specific example, when I see Delete and Remove, I do not assume they do the same thing because they are labeled differently. But Joint with Rigid specification and As Built Joint with Rigid specification create the impression that they achieve the same result - and that the difference is simply that in the Joint case it moves components around, whereas with the As Built Joint, there is no need to specify a component move because the components are already perfectly placed.

Clearly this post was put in the wrong Forum, and for that I apologize. I wasn't looking for clarification or assistance, but trying to give user interface improvement feedback to the F360 team. I am now in direct discussions offline with the appropriate individuals in the F360 team (who agree with my view), and I now consider this matter closed.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

TrippyLighting — Sat, 09 Oct 2021 01:33:31 GMT

@davidpbest wrote:

I don't really understand why people keep piling on in this thread with unrelated commentary.

I responded directly to one of your statements, which I quoted in my post. How is that unrelated ?

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

TheCADWhisperer — Sat, 09 Oct 2021 12:20:30 GMT

@TrippyLighting wrote:
There are a number of abstract concepts such as the difference between "delete" and "remove" or the "as-built joint", that do not exist in that form in other CAD systems.
In a top down design where everything is designed in place...

There is no concept being discussed in this thread that isn't essentially the equivalent in other history based parametric CAD systems. Bodies/Components/top-down/bottom-up/Constraints/Joints it is all the same at the logic level. Geometry is geometry. Coordinate systems are coordinate systems. Origins are origins.

Now one program might have a macro assigned to a glyph of a certain name that automates a bunch of stuff (Joints as one example) that might require more (or different) steps than in another program, but in the background they have to follow the same logic. There is no "new math" here.

Unless we are talking about t-Splines or Generative Design or converting triangular faceted mesh to b-rep, there is nothing unique about Fusion 360 compared to other CAD softwares. An understanding of geometry and logic helps get past the assigned names. That is why we do CAD rather than merely write a paragraph about our Design Intent.

If necessary, I can create a video about the original Rigid Joint question and show how it is logically the same in other CAD programs (the OP mentioned SOLIDWORKS), but unless requested - I need to get some yard work done instead while the rain has stopped for a bit.

BTW - I demonstrated top-down, bottom-up and xref of 3D CAD in AutoCAD in the last century for the interview process to secure my current position. Other than parametric history rather than direct editing, pretty much the same logic. 🤔

I think we've beating a dead horse here.

Re: Rigid Joint discrepancy in maintaining spacial relationships when resizing component.

davidpbest — Sat, 09 Oct 2021 18:53:56 GMT

I think we've beating a dead horse here.

Sounds like one hand clapping to me. As the OP, I declare this topic closed.