Bug report: Flange unexpectedly moves away from profile sketch

[griffin.alberti]

Sometimes, after editing the first flange of a sheet metal component whose origin is not in the same spot as its parent component’s origin, the sheet metal body will unexpectedly move away from its profile sketch. See this screencast and attached file for example. To reproduce the bug in the attached file, just edit the flange operation in the timeline.

This seems to happen only if:

1. The sheet metal component’s origin is moved (and/or rotated) before the flange operation
2. The sheet metal component is not the active component when editing its flange operation

Steps to reproduce from scratch:

1. Start a new design
2. Create a sheet metal component
3. Move the sheet metal component and capture position
4. Activate the sheet metal component
5. Draw a simple profile sketch on it
6. Create a flange from that sketch
7. Activate the root component
8. Edit the flange operation in the timeline (you don’t have to change its parameters, just double-clicking it and pressing enter will do)
9. After this, the flange should inexplicably move away from its profile sketch

Note that it doesn’t seem to matter how the sheet metal component was moved, so long as it was moved before the flange operation. If it’s moved by joining its origin to a sketch point or another component, for example, the same bug happens.

I often like to join new components’ origins to other parts in an assembly before modeling them, so I've run into this bug many times while creating sheet metal parts over the years. Up until yesterday I wasn’t able to reproduce it intentionally, but the method I just described seems to do the trick.

[jhackney1972]

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@griffin.alberti wrote:

Sometimes, after editing the first flange of a sheet metal component whose origin is not in the same spot as its parent component’s origin, the sheet metal body will unexpectedly move away from its profile sketch. See this screencast and attached file for example. To reproduce the bug in the attached file, just edit the flange operation in the timeline.

This seems to happen only if:

1. The sheet metal component’s origin is moved (and/or rotated) before the flange operation
2. The sheet metal component is not the active component when editing its flange operation

Steps to reproduce from scratch:

1. Start a new design
2. Create a sheet metal component
3. Move the sheet metal component and capture position
4. Activate the sheet metal component
5. Draw a simple profile sketch on it
6. Create a flange from that sketch
7. Activate the root component
8. Edit the flange operation in the timeline (you don’t have to change its parameters, just double-clicking it and pressing enter will do)
9. After this, the flange should inexplicably move away from its profile sketch

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Your process does indeed displace the sketch from the model but you are violating the correct process for editing a component.  In step 7 you activate the top level component and then proceed to edit the new component in step 8.  Good modeling practice dictates that your ALWAYS activate the component, you intend to edit, before the edit occurs.  This applies to modifying or adding any new features to the component.  If you follow this rule, you will not see any issue.

[dsouzasujay · Accepted solution]

Thank you for reporting the bug @griffin.alberti .

Thank you for sugessting good modelling practice @jhackney1972 . 

I have logged a defect FUS-79038 for tracking internally.

[griffin.alberti]

Thanks for the help, both of you!

Good point @jhackney1972, yep, I'm familiar with the intended workflow and it does prevent the problem. It can still be a bugger though if I slip up and cause a flange to move a tiny bit, then only notice it after a bunch of work. Other than recreating the part, I haven't found a fix for the problem once it's far off in the undo history.

Out of curiosity, other than avoiding this bug and building good habits, are there any specific reasons it's important to activate the correct component before editing preexisting features like this? In my experience, having the wrong component active only seems to cause problems when creating new features, so I generally don't worry about it if I'm editing features that already exist. Once an assembly is modeled up, I often find myself massaging the shapes of parts just by editing features in the timeline, and it's nice to be able to bounce from feature to feature without worrying about which component is active. Just wondering if I'm missing something important here!

[jhackney1972]

The first thing I would suggest is to never use the Move command unless it is absolutely required.  I use the Align command if I need to put a component or body in position, I simply drag components but of course I use the Joint command the most.  You are absolutely correct, if the model is constructed correctly, the activation of a component is not necessary but if the bodies and sketches are located under the component, as they should be, if you edit a sketch or edit a feature under a component, it is activated automatically.  In the Screencast I mention this and a few other reasons I like to activate a component for both creation and editing.  

[griffin.alberti]

Wow, what a detailed explanation! I also avoid the move tool in favor of joints while assembling things, but I actually haven't been using the align feature at all. No doubt it will come in handy. And I didn't realize Fusion automatically activates components whenever one of their features is being edited. Interesting. Thanks for the tips!