DMT 6" Diamond Whetstone Sharpener with Plastic Box

Ideal as a first sharpening stone for a novice woodworker


DMT 6" Diamond Whetstone Sharpener with Plastic Box

There several types of sharpening stones (aka 'benchstones') that you can use to maintain your chisels, plane blades and other cutting tools in tip top shape — oil stones, natural waterstones, synthetic waterstones, and diamond stones. Waterstones are perhaps the most widely used, and for good reason. They're easy to use and maintain, come in a wide range of grits, from extra coarse to super fine, and are widely available. However, diamond stones have their own distinct advantages, making them useful additions to any sharpening arsenal.
DMT, one of the worlds major manufacturers of diamond benchstones refers to their stones as 'whetstones'. The word 'whet', which has largely disappeared from our vocabulary, simply means 'to sharpen'. You can use the terms 'diamond benchstone' or 'diamond whetstone' interchangeably.

Interrupted surface (L); continuous surface (R)        
Diamond benchstones come in two styles — those with an interrupted diamond surface (which DMT markets as their 'whetstone' line), and those with a continuous diamond surface (which DMT markets under their 'Dia-Sharp' line). Stones with an interrupted surface contain recesses that serve to capture the swarf produced when sharpening. This style is ideal for sharpening wide blade tools or flattering waterstones. Continuous surface stones work best when sharpening narrow blades, like carving tools or thin blade knives, whose narrow tips might get caught in the recesses of the interrupted surface stones.

Types of diamonds used in benchstones  (Courtesy of DMT)         
The diamonds used on whetstones come in two formats — monocrystalline and polycrystalline, and they can be either natural or synthetic. Monocrystalline diamonds, as shown in the illustration above, are single un-fractured diamonds, which are bonded onto the benchstone plate, while polycrystalline diamonds are clusters of fractured diamonds bonded to the plate. DMT uses only industrial quality monocrystalline diamonds, as they wear down more slowly, resulting in a longer benchstone life.
The two major characteristics of diamond benchstones are that they cut very quickly, and they are extremely flat and will remain so throughout their life span. If you've used waterstones you'll know how quickly they dish out.
DMT diamond benchstones have a couple of other advantages. DMT specifies a surface tolerance of +/- 0.003", sufficient to ensure that you can obtain consistently flat backs on your plane blades and chisels. As well, they ensure that the diamonds used on their benchstones are consistent in grit size, that the diamonds cover the plate uniformly, and that they are applying the maximum number of diamonds per square inch of plate. The result is, according to DMT, a super flat surface that maintains consistent, even contact with the surface being sharpened to produce a superior finish, from end to end.

DMT Whetstone lineup (L to R): Extra Fine, Fine, Coarse, Extra Coarse    
DMT's Diamond Whetstones come in 6" and 8" sizes, stored either in a wooden box or a plastic container. The stones are available in four grades:

GradesModel #Mesh SizeMicron Size
Extra CoarseW6XP22060
I tested the DMT 6" Diamond Whetstone Sharpener with Plastic Box (W6FP). The whetstone measures 3/4" x 2" x 6", and comes packaged in an impact resistant plastic storage box.

Small recesses in the plate trap swarf    
The surface of the W6FP consists of a perforated steel plate molded into a rigid plastic body. The diamonds are embedded in a nickel plate that is bonded to the steel plate. The 1/8" recesses in the surface serve to trap the swarf (metal debris), keeping it off the sharpening surface.
As with waterstones, use water, rather than oil, as the lubricant. A small spray misting bottle is convenient, as you don't need to use very much water. Keep a roll of paper towels or an old rag handy, and wipe the whetstone every couple of minutes, before the surface becomes covered with swarf. A couple of squirts of water and it's back to work. It's important to keep the surface clear of debris so that the diamonds can work more effectively.


Durable base with rubber feet   
The storage box has a clear, removable cover. The whetstone fits over a lip on the base,  while rubber feet on the bottom of the base provide some stability in use. However I did find that the whetstone had a tendency to move slightly backward and forwards on the base. I resolved this by putting a small piece of duct tape along the lip to tighten the gap between the whetstone and the base.
I placed the base on a sheet of melamine, and it didn't move at all throughout the sharpening session. Holes in the base enable you to screw it to a substrate for a more permanent arrangement.

L to R: Factory back; honed on W6FP; honed on 8000 grit waterstone

L to R: Factory bevel; sharpened on W6FP; honed on 8000 grit waterstone  
Most hand planes and chisels come 'factory sharpened', ostensibly ready for use. However, 'sharp' is a relative term. In general, new planes and chisels will benefit from honing the bevel. Honing does two things — it removes the inevitable milling marks left on the tool, and it produces an even keener cutting edge, enhancing tool performance. The back of plane and chisel blades can also benefit from honing. It used to be very common that the backs would be dished (have a slight hollow), which would require flattening. This seems to be less prevalent today. However, the backs can still have discernable milling marks that most woodworkers will want to remove.
Fortunately I had a new Irwin Marples 6-piece chisel set in the shop, which made for perfect test subjects. The backs on five of the chisels were virtually dead flat (there was a slight blemish on the 1/2" chisel). Milling marks were clearly visible on the back side and bevel of all the chisels - see the left most chisel in the two photos above.
It took me an average of 150 strokes on the W6FP to remove the milling marks on the backs, and about half that number of strokes to hone the bevel. After the first 100 or so strokes (about 40 for the bevels) the milling marks had virtually disappeared, replaced with a uniform pattern or small scratches. You can, to some degree, affect the surface finish by applying lighter strokes as you draw to the end of your honing session. A further 50 strokes (25 on the bevels), with decreasing stroke pressure, resulted in the finish seen on the chisel in the middle photos above. I expect that as the stone breaks-in it may produce a somewhat finer scratch pattern. Still, to achieve a more polished finish requires moving on to a finer stone. The extra fine DMT whetstone (W6EP) would, I assume, have provided a more polished finish. Not having one on hand, I opted to use my 8000-grit waterstone. Twenty-five strokes produced a fairly polished surface, shown on the right most chisel in the photo.
I cleaned the surface of the W6FP after honing each chisel, and at the end of my honing session I used the W6FP to true my waterstone. It worked superbly. I make it a practice to true my waterstones on a regular basis, often right after a honing session, rather than waiting until the surface appears dished. It doesn't take much time and the stones are always ready for use.

The DMT Diamond Whetstone - easy and convenient to use     
I found that the DMT W6FP Diamond Whetstone cut fast enough, leaving a uniform scratch pattern. For small tools and chisels, the 6" model works fine, however, I would likely opt for the longer 8" model for use with plane blades. You could choose to go straight to work with the finish produced by the W6FP, but most woodworkers will opt to move on to a polishing stone.
If you're looking for a first sharpening stone, then I do recommend you consider a diamond whetstone, particularly if you are new to woodworking. They cut quickly, will never dish out like waterstones, and will last a long time - perhaps a lifetime for a hobbyist woodworker. You'll also find that they are competitively priced.
They are also an excellent choice for a contractor. You can store one in your tool kit without worrying that it will break. Unlike waterstones, which are quite fragile, a whetstone is super rigid and very durable.



  • 3/4" x 2" x 6"
  • 600 mesh/25 microns
  • Monocrystalline diamond surface
  • Surface tolerance of +/- 0.003"
  • Water lubrication
  • Plastic case with non-skid rubber feet
  • 90-day full refund

SOURCE:Find a Dealer
The DMT Store
Carl Duguay, December 2012
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