We get a lot of questions about how to set Heights: for bore operations in turning. The following graphic explains how heights work when using a boring bar.
The meaning of heights for boring bars may at first seem reversed. That is because, in OD turning and milling, height values get larger as the tool moves away from the part. However, with a boring tool, heights get smaller as the tool moves away from the finish, as shown in the ISO view below.
A good way to visualize this is shown in the Right view below. Imagine the part is sliced in half, and that you are looking down at the bottom half at the finish diameter. Viewing the part like way, Heights look and act exactly like a Mill part: Bottom: is the finish, Top: is the rough stock of the bore (usually the previous drill radius), then Retract and finally Clearance.