How do I reduce an Arc Diameter without scaling?

RiverArch 2.skp (1.9 MB)
Is there a way to narrow an arc without scaling the whole thing? See .skp file. I need to remove the outer arc from beyond the arc I created on the face. Another words, to lop off the outer 60’ of the overall arc, while leaving everything else the same size. Of course, I will need the full 3D arc with an outer shell too. The dimensions of the remaining arc cannot change. I was thinking of using pushpull to just push in the outer part until there is nothing left, but I can’t get it to separate just that outer part so I can push it in.

The inner arc is not within the context of the main arc component. Just copy/cut the inner arc and paste in place while within the component context. This will create the isolated surface that you can push-pull back. There will be a problem with push-pulling all the way back because the arch base surface is not coplanar. You can see this because a diagonal edge is needed to complete to create the surface (View> Hidden Geometry).

The bottom surface will have to become coplanar in order for you to push-pull all the way back.

CD

Thanks for showing me that. I hadn’t realized I had distorted the faces so much. I decided it was better to just recreate the main arch the way I wanted it. It’s getting much easier now that I’ve gotten a few basic techniques mastered…