I would highly recommend going to the library or buying "Hand Tools: Their Ways and Workings" by Aldren A. Watson. It is published by Norton, and is a treasure trove of information on how to optimize and use hand tools, including scrapers. He not only talks about flat scrapers, but how to make and use scrapers from piston rings, from the tangs of old files for grooves and making rounded moldings, etc.
This book really taught me how to use a draw knife and spokeshave as well, for chamering, fine scraping and wood removal, making curved surfaces, rough stock removal, almost all things that a bow maker does. The illustrations are just amazing, too.
Dane