+-Let the angle at which an edge approaches a surface determine whether it is cutting or scraping. An angle of approach lower than 90° means the edge is cutting. An angle of approach greater than 90° constitutes scraping. Cutting is characterized by continuous shavings, leaving surfaces smooth on a very small scale. Since fibers are being lifted from the wood, tearout is possible. Scraping generates more broken fragments than shavings, leaving surfaces somewhat torn and roughened on a very small scale. Since fibers are being pressed against the wood, tearout is virtually eliminated.
http://www.highlandwoodworking.com/library/images/cutting_vs_scraping2.jpgTh is is an arbitrary definition and as such may be subject to dispute, but we've found it as useful a way as any to answer your question. Now it should be clear why I claim that a properly burnished card scraper is actually a cutting tool. Though the card itself may be held at approximately 120°, its tiny burr approaches wood at an angle just a little higher than 25°, lifting clean, ultra-thin shavings and leaving surfaces practically in finished condition. The hardened blade of a scraping plane, on the other hand, is not always formed into a burr after sharpening. Thus it is presented to the wood at an angle of 90° to 110°, performing a true scrape. [Non-text portions of this message have been removed]
