Scrapers for Woodturners, Part I: Traditional ScrapersComments (0)
Scrapers for woodturning are generally used to refine shapes, help eliminate rough spots, and reduce tear out– all in an effort to minimize sanding. They do not cut with a sharpened edge like other tools, but rather with a burr which is raised on the cutting edge. A properly sharpened scraper will shave off very thin ribbons of wood. If a scraper is producing sawdust, it’s time to raise a new burr by burnishing the non-cutting side, which pushes a thin layer of metal to the cutting side and forms the burr. Burnishing can be done by a traditional burnisher,
diamond hone, or even sandpaper.
A traditional scraper usually has a 70 or 80 degree bevel and a flat top. The burr is raised at the intersection of the bevel and top by burnishing the bevel. When turning, the scraper is held in a slight handle-raised position (about 5 to 10 degrees) with the burr at the center line of the turning. Unlike other tools where one rides the bevel, with a scraper only the burr is contacting. Used this way, scrapers can be grabby and lead to some interesting catches until one gets the hang of using them.
Diagram of forming a burr on a scraper
The burr is raised by using a two step process. First, the bevel and top should be flattened (some fine grit sandpaper or a favorite sharpening system works fine). Second, the bevel edge is compressed and bent by either using a burnishing tool for card scrapers (a hardened rod with a handle), a small diamond hone, or even some fine grit sandpaper on a flat surface. Regardless of which method is being used, the bevel edge of the scraper
should be tipped about 10 degrees off the burnishing tool so it does not rub. While applying a good bit of pressure, slide the burnishing tool along the scraper to compress the edge and form the burr.
The process can seem a little daunting and complicated, but with a little practice the results are well worth it. I was fortunate to have met the product development manager from Robert Sorby who came to the Harrisburg store when I was just starting out as a turner. At that point, I hated scrapers because I couldn’t get them to cut right and was always getting catches. In a few short minutes he showed me the correct way to sharpen and use a scraper. Consequently, for the last ten years I have been using them for a variety of tasks, even final shaping a bowl after using my bowl gouge.
In the next article, I’ll talk about negative rake scrapers and how they are similar, but also vastly different from a traditional scraper.
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