I run into this problem a lot and finally decided to post. I often have two sets of adjacent faces both of which I want to set smooth. However, I do not want the two sets to blend into each other; i.e., I want a hard or sharp edge between them. Here’s an example:
I want the tall base part and the overhanging part to be smooth, but I want that selected edge between them to be sharp. How can I make that happen?