This tool can be used to rotate the model in any direction.
Select the Rotate button.
Hotkey H will also initiate the tool.
Rings will appear around the three axes of the model.
Select the model in any location to perform a free form rotation.
While in free form rotation mode, hold the SHIFT key to lock the rotation direction to a single axis. The rotation axis will be locked to the last direction in which it was rotated. OR select one of rings to rotate the model along the chosen axis.