VERITAS Scraper Burnisher for Woodturners
Traditionally, wood lathe scraping tools are used straight from the grinder. The burr that develops during grinding becomes the cutting edge. The problem is that such a burr is jagged and fragile, necessitating frequent re-grinding to maintain a "sharp edge". Not only is the tool quickly used up, but the finish of the workpiece is poor, requiring heavy sanding.
The Veritas Scraper Burnisher eliminates these problems. The burnisher forms a sharp, continuous hook. Scrapers sharpened using this Scraper Burnisher are easy to control, produce a superior finish, and last longer between sharpenings. It is the only burnisher that can be used with high-speed steel scrapers.
- Two carbide burnishing rods are supplied. One is ground at 10° for burnishing scrapers with bevels of 70° or 75°. The other rod is ground at 5° to burnish 75° to 80° bevel angles.
- Lap the face with a fine sharpening stone or lapping abrasive to remove any burr.
The burnisher should be held in a vise or screwed to a stationary surface. Select and install the carbide rod best suited to the bevel angle desired. Place the scraper face up on the scraper burnisher. With one hand, press the scraper down onto the burnisher surface while grasping the handle with the other hand. Position the edge against the conical surface of the carbide rod and draw the edge past the rod with solid pressure against it, using the handle as a lever and the pivot pin as a fulcrum. Firm pressure is required to produce a hook, especially on high-speed steel tools.
Heavy pressure produces a coarse hook for roughing and shaping.
Light pressure produces a finer hook for more delicate work.
The carbide rods and pivot pin are a slip-fit in the holes. The three unevenly spaced holes allow you to obtain different fulcrum-to-burnisher distances to best suit the radii of different scraper edges.
Note: If you do not intend to change fulcrum-to-burnisher distances, sliding either rod into place with a strip of plastic will secure them, avoiding accidental loss when moving the burnisher about.
Traditionally, sharpened scrapers have to be presented to a workpiece at a negative angle (Fig. 2a) to allow the burr to begin its cut. This presentation can lead to severe digging in of the tool.
A scraper burnished with the Veritas Scraper Burnisher should be presented to the work with the bevel rubbing, then the handle lifted slightly until the tool begins to cut (Fig. 2b). A properly sharpened scraper should produce long, continuous shavings. For end-grain work, the scraper can also be used tilted for a shearing cut.
You should not put excessive pressure on the scraper while turning; the cut is self regulating. Trying to overfeed the tool will cause chattering. If you want a coarser cut, apply heavier pressure when burnishing to produce the larger hook needed.
When the tool stops producing shavings and starts to produce dust, it is time to resharpen.