One of my favorite sharpening tools is a diamond paddle. I use it for router bits, knives and, most importantly, scrapers. The problem is that it cuts so fast the tiny spaces between the diamonds quickly fill with metal particles, called swarf, which slows or even stops the cutting action. Most instructions suggest using water to wash away the swarf. Water works well enough, but household oil works much faster.
Every sharpening tool, whether it’s a file, waterstone, sandpaper or this diamond paddle, cuts faster when it’s free of swarf buildup. Fast is good, because the fewer strokes you take, the more accurate you’ll be.
This story originally appeared in American Woodworker July 2006, issue #122.