3D sketch fails on geometry update

[torbjorn]

I am currently working on a concept for his stairs, and the geometry is a bit complex. Still a lot of details missing, but I paused here to share an annoying issue with some of the 3D sketches. The railing is swept, using 3D sketches based on included edges of surface. The top rail on one surface, the lower ones on a second surface. 

When I change the diameter of this curved stair, 3D sketch based on the first surface survives but the 3D sketch based on the second surface fails. But even worse; when I change back to the original diameter, the second 3D sketch still fails. 

The only way to fix this is to delete all included geometry, and include again. Cumbersome - and not as expected for a parametric model.

Enclosed the part if anyone wants to try by themselves.

Any suggestions for workarounds? Or maybe a less complex way to model this?

Torbjørn

(Inventor 2017.3)

[johnsonshiue]

Hi! This is an interesting case. I am still trying to understand the dependency. I do see an intriguing behavior though.

1) Open the part.

2) Make all solid bodies invisible.

3) Make all surface bodies visible.

4) Edit 3D Sketch10 -> delete all the included edges -> include them back -> Finish Sketch.

5) Change d0 from 5700 to 5500 -> Update.

Now 3D Sletch10 will not fail. This leads me to believe that the included edges were associated to corrupted reference or something. Could you take a look and see if you notice the same behavior?

Many thanks!

[torbjorn]

Thank you for using time on this issue.

I am trying to replicate your steps, but the 3D sketch still fails for me. Maybe this is related to my 2017.3 version only?

Anyway, I discovered strange behavior for the extend surface feature (Extend9). The number of edges included seems to be altered when the value of d0 is changed and generates an unexpected result for srf26. And since the 3D sketch 10 is using these edges, I can understand why the included edges fail.

Thanks,

Torbjørn