Inconsistency with Projected Geometry in Assemblies

[Anonymous]

I'm struggling with some inconsistency in the behavior of projected geometry in the assembly setting.

Below are some screenshots that show the issue.  It's not a very real world scenario in this particular example, but it shows the inconsistency well.

I'm creating a sketch on the work plane in the foreground.  I projected geometry from the cylindrical port (circled in red).  Some of the geometry projects onto my sketch in yellow (associative) and some of it projects in dark purple (fixed).  See the auto-applied constraints in the second screenshot.  The two yellow lines and the two outside purple lines were selected from the model itself.  The center purple line is one of the planes in that cylindrical port (selected from the model tree).

Why does some of the geometry come in as associative while other geometry is fixed?  I've read up on the fact that projected CUT geometry won't be associative, but hopefully it's clear in this example that the item I'm projecting isn't cut by the sketch plane at all.

Thanks,

Mark

[kennyj]

@Anonymous,

Thank you for the examples.  I'm not sure I can provide anything - just want to be on the string so I can see the answer.

Is the projected part fully constrained in the assembly?  From the horizontal lines, can you drag the cylinder up or down?  Is the cylinder itself modeled using adaptive geometry / features?

Kenny

[Curtis_Waguespack · Accepted solution]

Hi mark.bergstrom,

There are several areas in Inventor where the behavior is not real obvious to us as users, and it takes an deeper understanding to know what is going on. That deeper understanding is often only possessed by the developers, and sometimes they help us understand it.

So with that said, I'll attempt to klutz through an explanation as I understand it, and then someone who has a better understanding of this can correct me where I'm off base.

When you project an edge that doesn't actually exist in the component, or would only exist if your sketch plane were sectioning the model, such as the tangent edges on the cylinder or a work plane in a component, Inventor projects them by "deriving" them as they are at that moment, and makes them non-associative. Other edges that are "true" edges that can be selected in the component model are made associative.

I think that's the difference you are seeing here.

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com

[johnsonshiue · Accepted solution]

Hi! Indeed, the behavior is a bit confusing. The grounded ones came from silhouette edges, which are not actual edges. They are more like contour of an object in a given direction. There is no reliable way to define it and keep it associative. the associative ones are projected from real edges.

Many thanks!

[Anonymous]

Thanks for the input, guys.  I can get my head around that.  And it seems consistent with the behavior I've experienced.  Better understanding for all!

[Justin_DeSilva]

My assembly was suffering from a similar circumstance and might be a result of modified registry theme settings not allowing me to differentiate between projected associative versus projected grounded geometry.

Curtis or Johnson, can we differentiate between projected associative and projected grounded geometry using registry settings?

Projected Associative - ReferenceCurveColor

Projected Grounded - ?

[johnsonshiue]

Hi Justin,

Unfortunately, there isn't a setting to control the behavior that I am aware of. In theory, all should be associative. Any non-associative behavior should be considered a limitation or deviation from the principle. There is a workaround to make it associative though. Instead of projecting the silhouette, make it a true edge. Edit the part and split the cylindrical face using a workplane. Now, you have real geometry. The projected edges should be associative. Would it work for you?

Many thanks!

[Justin_DeSilva]

I'm not certain why my features weren't updating but after modifying the CurveReferenceColor key from custom color black to it's original color yellow, all associative features are updating. Each yellow construction line is an associative projected edge from a relative component.