In looking at Harris' book on 'Boilermaking', I notice drawings for various valves-such as safety valves. I have a small lathe, drill press and various other tools. While drawings are interesting they're not very descriptive in the 'How to' department. One of things that puzzles me is how to cut a good, or proper shoulder, or 'seat'. Are there any tutorials out there dealing with the subject. I'd like to be able to make a whistle, too. You start buying this stuff, and the price adds up quickly!