David, Listen to Bob. The most important tool in bow making is patience!
After floor tiller I only use a scraper to remove wood. It takes a lot longer but my bow building has improved 100% since I started.
As your stave gets closer to being a bow, it doesn't take much wood removal to go from 60# to 30#. At this point you should take a measured amount of strokes from each limb(provided they are bending evenly and together), exercise on the tiller tree and check weight before you remove any more wood. Keep at it. You'll get it soon. It took most of us a few bows, at least, before it clicked.
Pat