How To: Use a Scraper
A tool for minimalists, the scraper is perfect for those who admire simplicity of form and function beyond all else.
This is a tool for minimalists, for those who admire simplicity of form and function beyond all else. That’s because the hand scraper consists of little more than a piece of high-quality steel in the shape of a playing card, only slightly larger, typically two and a half by five inches, and about a thirty-second of an inch thick. (Let it be noted here, though, that while most scrapers are rectangular, there are curved ones, too.) In earlier centuries, the hand scraper was made from broken sawblades. The broken blades were of quality steel that otherwise was of no use.
Even today, the hand scraper is quite a bargain, costing only about five dollars.
The cabinet scraper is a hand scraper mounted in a frame that resembles a spokeshave. A pair of set screws holds the blade in position, and a thumbscrew allows for fine adjustments of the scraper blade.
Scrapers are a good deal more intriguing and useful than they may at first appear. One of the edges is “sharpened” in order that the tool can smooth wood, usually hardwood. It won’t lift the grain of the wood and, while it performs something of the same function as sandpaper, its waste products are small shavings rather than dust. A scraper will remove as much material as medium-grade abrasive paper without introducing the countless little scratches that sandpaper leaves behind.
Another advantage is that the scraper’s shavings are easily brushed off, while the sanding dust can clog the grain of the wood. There is simply no newfangled machine that can do as good a job at producing a smooth finish on a wood surface. The scraper will also allow you to work in areas much smaller than those you could smooth even with a block plane, and without encroaching upon adjacent portions of the wood.
The cutting edge on the scraper is actually a tiny burr, a small projecting lip at the edge of the tool. Almost imperceptible to the human eye, the burr (or hook, as it is also called) makes the scraper a very efficient smoothing tool. The sharpening process, during which the burr is rolled over to form the edge, is trickier even than using the tool once it’s been sharpened.
Sharpening the Scraper. When your scraper produces dust rather than shavings, it needs to be sharpened. In keeping with the simplicity of this tool, this task probably won’t require a file or even a sharpening stone. Most of the time, a rounded piece of steel is all you’ll need. The back of a gouge will do, though a tool made for the purpose, called a burnisher, costs about fifteen dollars. We’ll get to the burnisher step in a minute, but there are other stops first.
A scraper with a badly dulled or pitted edge needs to be filed. The long edge of the scraper is drawfiled, meaning the scraper is clamped in a vise and a single-cut mill file is drawn along the edge.
In this and other steps, a key consideration is straightness: You want the edge straight and perfectly perpendicular to the face of the scraper. The scraper is ready for the next step when the corner at which the face and the edge meet (called an arris) feels sharp to the touch.
Now, hone the scraper on a sharpening stone. Use a medium stone first, honing first the face, then the edge of the scraper. Repeat with a fine stone. Again, your goal is a perfectly perpendicular edge that is perceptibly sharp to your fingertips.
Now comes the clever part (and it’s here you will return when your scraper isn’t truly dull, but just needs tuning up).
Begin by holding the scraper flat on your benchtop or other work surface. The burnisher is then held at about a five-degree angle to the scraper (just off horizontal). Run it back and forth along the arris. This will produce a burr parallel to the face. If you don’t hear a noticeable click as you drive the burnisher off the edge of the scraper, you’re not applying enough pressure. Now, having raised the burr, you must turn it over. To do so, you draw the burnisher once along the edge of the scraper, holding the scraper at about an eighty-five-degree angle to the scraper. Larger burrs can be turned by two or more passes, but start with one pass. The fine hook of steel you’ve shaped will do the actual work.
Note that if you do both sides of a working edge of a scraper, you can then scrape with both sides. Or even both sides of both long edges of a scraper, producing four hooks.
Scraping the Surface. Actually putting the scraper to use is about as far removed from machine work as you can get. It’s just your hands, the workpiece, and your scraper.
The scraper is gripped with the first two or three fingers of each hand at the front of the tool, with the thumbs behind. Angle the top of the scraper away from you (at roughly seventy-five or eighty degrees to the workpiece). Gently push the scraper, scraping along the surface of the wood, applying enough pressure to the rear of the scraper so that the bottom edge forms a slight curve. That means the corners of the scraper will lift slightly off the wood and the center will make contact with the surface to be smoothed.
The pressure you exert with your thumbs determines the sharpness of the curve, which in turn determines the nature of the cut. More bending means that less of the scraper scrapes the surface (good for highly localized scraping, as is necessary to remove a specific imperfection in the wood); a nearly flat application is preferable for an overall scraping job.
As with smoothing flat stock with a bench plane, work first diagonally across the workpiece. For smoothing surfaces, work in long strokes across the wood, introducing as little curvature into the scraper as possible. Put pressure on the scraper only after it’s in motion; lift the scraper from the surface as you reach the end of each stroke. For the final smoothing, work with the grain. Scrapers also remove excess glue with ease.
Scrapers can be used to smooth localized imperfections like knots. Keep in mind, however, that too much intensive scraping in a small area may make that area stand out from the surrounding wood. One good rule of thumb to apply: For every two or three scrapes you make to fix the localized problem, scrape a long stroke on either side. For every three or four local scrapes, scrape strokes that are two scraper widths away. And so on.
When the scraper begins to dull, burnish the edge. Do both burnishing steps, forming the burr first by burnishing the face, then turning the burr by burnishing the edge.
The Cabinet Scraper. This tool resembles a spokeshave but is actually a hand scraper in disguise. It has an iron body into which a hand scraper is affixed, using thumbscrews. Once the scraper blade is set in place, this two-handed tool makes scraping easy.
Sharpening the scraper blade used in a cabinet scraper is a slightly different process from putting an edge onto a hand scraper. The cabinet scraper’s edge is first filed to a forty-five-degree bevel (a bastard mill file will do the job nicely). This raises a burr on the backside, which can be polished off with a few strokes on a sharpening stone, holding the back of the scraper flat to the stone. A couple of strokes across the bevel are next, to polish it.
Now for the burnisher. With the scraper bevel down on the workbench, smooth the back of its edge with a few strokes parallel to the face of the scraper. Then secure the scraper in a vise and burnish the bevel. Start at the angle of the bevel; gradually, lessen the angle (bringing the burnisher gradually toward the horizontal). The last stroke should be just short of horizontal, perhaps fifteen degrees. Insert the blade into the scraper and go to work.