It's hard to think of a simpler yet more effective woodworking tool than the cabinet scraper – a flat, thin, postcard-sized sheet of spring steel dragged by hand across a wood surface to leave a glass-smooth finish. Applications range from crude to fine, everything from scraping glue out of tight corners to coaxing a high-gloss finish from lacquer or shellac. Whether rectangular or shaped to conform to various contours, a properly sharpened scraper can tame the most contrary grains – even knots – without tearing out.
This remarkable ability comes from a microscopic, hook-shaped burr that is burnished (formed and polished by rubbing with a harder tool) along the scraper edge. In fact, "scraper" is really a misnomer: "micro-plane" is more accurate because the burr on a properly sharpened scraper actually slices, lifts and curls a continuous shaving much like a plane but on a scale so small that tear-out is virtually eliminated.
Whether a scraper micro-planes, or merely scrapes, depends primarily on the shape and quality of the burr, also known as a "hook." Then it's a matter of pushing or pulling the scraper across the workpiece with just the right combination of angle of attack, pressure and speed. It does take some practice; "just right" is found mostly by feel.
TIMBERLINE TOOL's SB-1 burnisher is designed to put micro-planing burrs quickly, easily and reliably on a wide variety of scraper sizes, shapes and thicknesses. Its burnishing pin is considerably harder (RC-62) than scraper steel. In the following process you'll discover how the SB-1 can turn a simple sheet of spring steel into a fine woodworking tool.
HOW TO USE A SCRAPER
Rectangular scrapers are usually worked with both hands either by pushing or pulling the scraper along the work piece.
Start by holding the scraper upright and slightly bowed, and gently push it across the work piece, gradually increasing the angle of attack until the burr starts to grab. Maintain the “grab angle” while increasing scraping pressure until a continuous shaving starts to roll off the burr. Once you get the feel of the “just right” angle and pressure, speed up the strokes, and there you have it – micro-planing.
Curved or shaped scrapers are usually pulled with one hand, but the principal is the same. Work the scraper shape along the corresponding work piece shape, upright at first and gradually increase the angle of attack until you find a "grab" angle that will micro-plane all across the shape.
Keep the grab angle at a minimum – just enough to make a continuous shaving. Avoid the natural tendency to press too hard or at too sharp an angle of attack. Either causes excessive heat which breaks down the burr and may even burn thumbs and fingers. Besides, it's too much work.
To prevent “wash boarding" the work piece surface, work the scraper askew to the line of travel alternating the skew angle to either side every other stroke or two.
Don't be discouraged if at first you do more scraping than micro-planing. It's largely a matter of feel that only practice can teach. But, once learned, it's a skill you'll have forever.
