Diamond sharpening stones have enjoyed a steady increase in popularity because they cut fast, never need flattening and last a long time. Here’s a new type from Atoma, a Japanese company, which may wet your interest.
Atoma plates are composed of monocrystalline diamonds electro-bonded to a thin sheet of stainless steel. That sheet is then mounted to a 10mm thick aluminum block, which is flat to within .0016”. Unlike other stones, where the diamonds are evenly spread, Atoma diamonds are arranged in clusters. According to the manufacturer, this results in a more aggressive cutting action. The clusters are arranged in a pattern that allows steel residue, called swarf, to collect in channels. With this design, the swarf won’t quickly clog the plate—a problem with all types of sharpening stones. Atoma recommends using either light oil or water to aid in swarf removal.
Atoma Diamond plates come in three grits; 140 for fast material removal, 400 for creating a primary bevel and 1200 for final honing. (The micron equivalents are 100, 45 and 15, respectively.) The plates are generously sized at 3″ x 8-1/4″, so they’ll easily handle your largest plane blades.
I found these stones made fast work of the tedious chore of lapping the backs of chisels and plane irons. Sharpening was quick as well, and produced a razor edge. Like all diamond plates, they’re pricey, but when my shop time is limited, their efficiency is worth quite a lot!