My daughter Katherine and I have just completed shooting and editing a short and free video on how I sharpen a card scraper. This technique works for both curved and rectangular scrapers.
This video shows a slightly easier way to deal with the faces of the card scraper. Several years ago when I started studying the burnishing of wood and other organic materials, I started wondering if a carbide burnisher was able to smooth and polish steel to the degree that fine sharpening stones do.
After a few years of experimentation with this technique, I have concluded that it works. And it works really well. I have stopped stoning the faces of my scrapers. So now my technique is to:
- Burnish the faces of the scraper to fold any hook or burr up onto the edge of the scraper.
- Stone the edge with a #1,000-grit waterstone to remove the fatigued metal and to cut a square and sharp arris (aka a corner). Then polish the edge with a #5,000-grit waterstone.
- Burnish the faces of the scraper to polish the steel faces and start deforming the metal up to the edge to make the cutting hook easier to turn.
- Burnish the edge with the burnisher parallel to the floor and edge of the tool.
- Tilt the burnisher 7° to 10° to turn the cutting hook.
After sharpening hundreds of edges, I can report that the burnisher polishes the steel like a mirror. And the edge continues to improve with every sharpening as the polish improves on the faces of the tool.
I haven’t tried this with high-speed steel (HSS) burnishers, only the carbide ones. So feel free to experiment yourself. I suspect the HSS burnishers will work fine, as long as they are harder than the steel in the scraper.
If you want to see still photos of the process, visit this page we created.
If you want to make your own card scraper with a curved edge, visit this page.
You can buy the Crucible Curved Card Scraper here in our store.
You can buy the ARNO burnisher we use here.
— Christopher Schwarz