DMT DiaSharp diamond sharpening plates

By Abhijit Menon-Sen <ams@toroid.org>

2015-12-30

A friend sent me a pair of DMT DiaSharp “bench stones”. These are steel plates surfaced with diamond particles—an alternative to old-fashioned oilstones for sharpening steel cutting edges. I have been using them for several months now, and they have lived up to their reputation as being fast, durable, and convenient. I am very happy with them.

I have the D6CX and D6EF, each of which has two continuous sharpening surfaces measuring 150mm*50mm (6"*2"). The D6CX has extra-coarse (220 grit) and coarse (325 grit) sides, while the D6EF has fine (600) and extra-fine (1200) sides.

I have used them to sharpen kitchen knives, sharpen and flatten the back of a very hard plane iron, restore the badly-damaged cutting edges of some old chisels that belonged to my grandfather, and hone some new Narex chisels and other assorted tools. I follow more or less the same process shown in this video by Paul Sellers:

The DMT plates are fast and a pleasure to work with. Flattening large steel surfaces does take a half-hour or so of extra-coarse rubbing (mind your knuckles don't scrape the plate! I learned this the hard way), but that isn't a task I would even attempt on my old Norton oilstone. Tuning up a blunted (not damaged) edge takes a couple of minutes at most, while restoring a nicked edge might take ten.

I use the plates with a bit of water sprayed from an old bottle of glass cleaner, and wipe them down afterwards with an old shirt. They are easy to maintain (but the coarse grits must be cleaned gently, because they will happily shred cloth), and do not need to be flattened periodically the way an oilstone might. The fine surface developed a few tiny black spots on the very first use, but extensive use thereafter has not made them any larger or more numerous. (DMT is reputed to have good customer support, but they didn't respond to my question about the black spots.)

(I also have the DuoBase stand. The rubber feet do keep it from moving, and the clearance makes it easy to flip the plates over. It works fine, but I could easily do without it.)

I like sharpening things, but I am not obsessive about it. I have not tried to measure how flat the surface actually is, nor have I looked at the sharpened edges under a microscope. The plates are flat enough, and the edges sharp enough for me; and it doesn't take too long to get them that way.

DMT manufactures a great variety of these plates: larger and smaller sizes, coarser and finer grits, single- and double-sided, or with “interrupted” surfaces that reduce the buildup of swarf (abraded steel particles that must be cleaned away). I might try a single-sided 8"*3" continuous surface plate someday—it should make it a little easier to sharpen my larger knives.