Jointing a board only affects one face.? Getting a tapered board upon repeated jointing is a not-uncommon occurrence.? But if you think about it, it makes sense.? The jointer's job isn't to achieve or maintain parallel faces; that's the job of the planer (i.e. thicknesser).? Once you get a face flat using the jointer, switch over to planer mode and use it to make that second face both flat and parallel.
