DMT W250FCNB DuoSharp Bench Stone Review
A ten-inch double-sided diamond plate that will not dish, does not need soaking, and flattens everything else in your sharpening kit.
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Sharpening arguments go on forever, but one thing is not in dispute: a flat reference surface is the foundation of all of it. The back of a chisel has to be flat to give a straight edge. A plane iron has to be flat where it meets the chipbreaker. And every waterstone in your kit has to be flattened against something.
A diamond plate is that something.
Why flatness survives
A waterstone works because its surface abrades away, exposing fresh grit. That is also why it dishes — the middle, where you work, wears faster than the edges.
A diamond plate is monocrystalline diamond bonded to a nickel-plated steel substrate. The steel does not wear. The plate you buy is flat, and it is flat in five years. That is what makes it usable as the flattening reference for everything else.
The interrupted surface
The DuoSharp pattern has holes through the surface. They do two things: swarf and slurry fall into them instead of clogging the cutting surface, and the reduced contact area means the plate cuts faster for the same downward pressure.
The cost is that a very narrow blade can catch on a hole edge. For chisels and plane irons it is a non-issue; for a small carving tool it can be.
Break-in is not wear
Every new diamond plate cuts ferociously for the first few sharpening sessions and then settles down. What is happening is that a few proud diamonds are being knocked off the surface.
People read the slowdown as the plate wearing out. It is not — after break-in the cutting rate is stable for years. Do not send it back.
Where it stops
“Fine” on this plate is around 600 grit equivalent. That gives a working edge that will cut, and it is not a polished edge. If you want a plane to leave a surface that needs no sanding, finish on a fine waterstone or a strop with compound after the diamond plate.
The sensible kit: this plate for flattening and coarse work, one fine waterstone, and a strop. That covers everything a furniture shop sharpens.
What works
- It stays flat. A diamond plate does not dish the way a waterstone does, so the reference surface your chisel backs are lapped on stays true for years
- Ten inches is long enough to sharpen a plane iron with a full stroke rather than working in the middle of a short stone
- Coarse and fine on one plate covers repair and honing, and it works dry or with a splash of water — no soaking, no slurry, no mess
What doesn't
- It cuts aggressively when new and noticeably slower after the initial break-in, which reads as the plate "wearing out" but is normal and then stable
- Fine on a DMT plate is not a polishing grit — you still want a fine waterstone or a strop for a truly keen edge
- Diamond plates are expensive up front compared with a pair of waterstones
Worth comparing against
- Check price
EZE-LAP
EZE-LAP DD8M/C Double-Sided Diamond Stone, 3 x 8 in
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Generic
Side-Clamping Honing Guide for Chisels and Plane Irons