Hi Jean-Paul, I examined your elliptical inset problem on a cylinder, and it seems to be failing due to an incorrect offset being created by the geometry library.

So unfortunately that's not going to be something easy for me to fix anytime soon.

As part of the Inset process, it creates a "plug" object, which in your elliptical case looks like this: (3DM geometry file also attached):



Then it wants to produce an offset of that plug, keeping the top and bottom surfaces in place and only offsetting the vertical one.

That offset is getting all messed up, you can kind of see a similar problem if you open up the attached 3DM file and just offset it using the regular Construct > Offset command, it creates this:



You can see that's not a proper offset.

When the geometry library's offset mechanism creates a bad result like this, it will prevent the Inset command from working properly.


< ..... After some more examination ....>


But one of the problems in this case seems to be related to the vertical surface being a single closed surface.

It does look like there is a possible work-around for some cases like this which is to split a closed edge so that it becomes 2 edges intead of one, you can do that by selecting the edge and running Trim, with the "Add trim points" option to pick a splitting point on the side opposite of where the edge's seam is (to see the seam extrude it and watch where the seam edge is on the extruded surface). Like this:





Once that edge is split into 2 edges instead of a single closed one, then Inset seems to actually work on that face:




So that's something you can try for that case right now, and I'll take a look at doing that closed edge splitting automatically inside of the Inset command.

- Michael