As I relentlessly bore down on the vibrating sander, I peered through the cloud of dust and saw Mr. McInturf motioning me toward him. As I turned off the machine and maneuvered between my high school Wood Shop classmates, I could see Mr. McInturf was holding a thin rectangle of metal, a shiny steel card of some sort. I watched, mystified, as he laid it near the end of his desk and rubbed what looked like a triangular file with no teeth against the faces and edge. Next, like some sorcerer in a green smock, he pushed that card along a board, lifting wispy curls before it and leaving a smooth surface behind. Then he handed it to me with a smile.
That was over thirty years ago, but I’m reminded of that magical moment every time I pick up a card scraper. I don’t use one often, but it is ideal for certain situations. If I remember right, chair maker John brown said it would be the tool he would grab if his workshop were on fire. I’d grab my adze, but I did pick up my card scraper recently for refining the surface of a bird bowl carved from a maple branch.
The photo above is from the post that I wrote about that bird bowl.
Here’s a shot of a scraper I like for sculptural shapes like this. I bought it years ago from Lee Valley, and I see they’re still selling them. This one is the thinnest of the four in that group (.016″ or .4mm). I’m sure there are other thin options from other suppliers out there, and you can also use an old handsaw blade. I’ve ground one edge to a gentle curve to add some versatility. I wrote a post a few years ago about using curved edges on scrapers for bowls.
The flexibility of this thin scraper allows it to conform to a variety of shapes and makes it light and nimble to handle. Thicker scrapers are better for heavier cuts and other situations.
There are tons of articles and information out there on how to sharpen a card scraper. I’ll add to the confusion by showing you how I go about it.
Regardless of the specific method, the main idea is to hone the edges and face and have them meet at 90 degrees. Then, using a harder piece of polished metal, deform that edge a bit to form a small burr toward the face.
Above, I’m honing the face of the scraper to remove any of the old burr. I just lay the stone flat on the scraper and go back and forth near the edge. Then I clamp the same sharpening stone in a hand screw clamp.
I don’t remember if I’d seen this exact method somewhere before, but there are lots of ways to achieve 90 degrees. Diamond stones are ideal for this, since they won’t be gouged by the narrow edge of the scraper. Clamped like this, the stone is held at 90 degrees to the side of the adjacent surface of the clamp. I keep the scraper flat and go forward and back on the stone. In the case of the curved scraper, I just rotate slightly as I move the scraper. I progress quickly to the finest stone on face and edge.
To create the burr, I usually use a burnishing rod, but you really just need any polished steel that is harder than the scraper. Here I’m using the backside of a carving gouge. Cover the tip of that gouge first for safety, or better yet, get something like this. I hope it goes without saying that I have no connections or deals with Lee Valley Tools, but I’ll make that clear anyway.
Put a drop of oil on and rub it along the edge.
Using a little pressure, run the burnisher along the edge smoothly, at 90 degrees a couple times. (I forgot to take a photo, but I rub the burnisher flat on the face a couple times before burnishing the edge.) Then tilt it a few degrees and run it again, then a few degrees toward the other face for one last time. Now both faces are ready to go. You can always use more pressure to make a more aggressive burr, but that is not necessarily better. Experiment and see what best suits your preferences and the situation. You can re-establish a burr a few times by burnishing before going back to the stones.
Then make magic like Mr. McInturf.