- Draw something with a cuttable category, like a Structural Column
- Draw a Reference Plan that intersects the element (even at an angle)
- Use Cut Geometry and click the element and then click the Plane
One easy way to determine if a family Category is Cuttable is by looking in the Object Styles dialog box. If there is a gray box in the ‘Cut’ column, that Category is not cuttable. See image below (from 2012):
For some further info, you can check out these WikiHelp pages:
Cuttable Families – WikiHelp
Non-Cuttable Families – WikiHelp
However, it would seem that the above lists are not exhaustive…
Also, you can check out my previous post about the subject:
What Revit Wants: Cuttable vs Non-cuttable families
You want to know which families are cuttable and which are not. Revit 2011 help gives the answer:
Cuttable families (link):
Curtain Wall Panels
Non-cuttable families (link):
What is a cuttable family?
If a family is cuttable, the family displays as cut when the cut plane of a view intersects that family in all types of views. From Revit 2011 help.