Can’t Keep Elements Joined & Conceptual Mass Add Edge

I’ve included 2 unrelated family scenarios below along with an alternate approach should you run up against similar conditions.

Can’t Keep Elements Joined

Say you have a solid sweep form in a family.  When attempting to cut the solid family with a void you receive a Can’t keep elements joined error:

This could potentially occur when the sweep geometry and the void geometry both contain curved profiles over a specific length.  Depending on the point of intersection Revit may not be able to cut the geometry in one pass.  This is usually magnified if the sweep geometry is joined to other geometry. 

The alternate approach involves using more than 1 void extrusion to cut smaller segments out of the solid sweep.  For example you would be cutting the same shape out of the sweep, but break it into smaller segments; for example use 3 voids instead of 1 large void like so:

This should avoid the error dialog and allow the same shape to be cut out of the solid extrusion.

Conceptual Mass Add Edge

By default when working on a mass, you can select a face > Add Edge to split the face with a new edge line.

For some forms, after a void has been added & cut this option will be unavailable. 

If you run into this you can get Add Edge functionality back by un-cutting the void through > Modify > Uncut Geometry.  Select the void then the mass it is cutting out to temporarily remove the cut. 

Then add the edge as needed to the mass.  When complete you can cut the void again under > Modify > Cut Geometry.