# Handling a Shared Edge

I have been spending the day trying to figure out better ways of doing things I have done in the past. While I’m on a roll, I thought I’d ask about this one that has some common element i’ve asked about over the past couple of day.

Here I have the parts of an assembly with three layers. Each layer shares a common edge (with the top layer being discontinuous). The issue here is that the edge is not shared continuously. The bottom and top layers pull back from the edge of the middle layer and do so a at different locations. I have the middle layer as an extrusion of a curve.

This seems to cause all kinds of problems. Getting the pieces together is a nightmare. I have to do a lot of exploding, joining, capping, and removing surfaces with non-manifold edges to get things together.

I suspect the problem is this partially shared edge.

Is there some good approach to take for situations like this?

Problem Edge.3dm (458.5 KB)

Hi Jim - assuming you are trying to make a single closed object- you don’t say, but I guess that is it.

-Extract the top and bottom faces of the middle thing.
-Extract and delete the faces of the objects that are coincident with these two faces.
-`DupBorder` the top and bottom objects and use the resulting curves to trim the faces extracted in the first step.
-`Join`.
In other words, deal with the surfaces rather than the solids.

-Pascal

Thanks. I had hoped there was some nice solid way to do it but you confirm it has to be done using surfaces. Thanks for all the help as I have been pondering how to do things better this weekend. I had been doing effective similar to what you described. The difference was that I was using CAP to fill the holes rather than dupedge and trim of the upper surfaces.

Addendum: I forgot to add that I I also have to split the split the surfaces where they diverge before joining them.