Rib feature doesn't work to my expectation

maarten_durie

Hi Onshape community

As part of my recurring exercises with TooTallToby's models, I liked to work with the Onshape surfaces making an egg cover.
However, using the rib feature, there's an anomaly of the rib not closing to the surface of the solid part, see image below.



As I don't have a clue where this might come from, I wondered if you have any suggestions or ideas on how to resolve this?
The link to the model can be found here (v2):
https://cad.onshape.com/documents/a97a1d80e6ec1bcc365f765a/w/4ce6169375ebd377eccb93e9/e/ee7cd865599a56c42df9f116?renderMode=0&uiState=63d3877cef705502fc62a42d

Thanks for your input!

shawn_crocker

I am not certain but it looks like the rib feature is getting a little confused by the fact that some of the part is passing through the middle of it.  As I suspect the rip feature is trying to find the extents of the parts faces so that it can create geometry up to those surfaces, the part passing through the ribs working area may be confusing the feature scripts.  Again, I am guessing here but do not really use the rib feature much.  If I was you, I would try create the rib in two parts.  Either creating one half of the rib and mirroring it over to the other side, or by splitting the sketch so that the rib is not going through the rib geometry that was created in a previous feature.

eric_pesty

The rib feature uses the first selection to determine the "extrusion" direction, which in your case was the arc in the left. If you switch it so the horizontal section is first it works fine:




When I modeled it I didn't use the rib feature but I should use it more! I didn't do it very efficiently but here it is if you are curious!

https://cad.onshape.com/documents/1c7decb361b84d534a49b607/w/83211343e8a2bbbb78ee3541/e/a67f636407e6486fc2fd4baa?renderMode=0&uiState=63d47e58c71fae593a3052cc

maarten_durie

Thanks @eric_pesty, your tip that the rib feature uses the first edge as an extrusion direction is very helpful, that will help me in the future.
Nice build as well!