I’ve always preferred diamond plates for flattening my waterstones and oilstones. Though a coarse or extra-coarse diamond stone does a fine job, the sharpening stones are pretty hard on the diamond impregnated surface, wearing the diamond plate prematurely, according to engineers at DMT.
I’m not a big fan, however, of the stone-based flattening systems I’ve used. I have yet to use one that stays flat enough. I have purchased two of the Norton flattening stones. Both were warped to the point of being unusable. After I flattened them (with a diamond plate!), they went out of flat after only a few uses.
I like Norton products. Lots. But not this one.
So I decided to flatten the product one more time.
Back in January, the president of DMT sent me a prototype of a flattening plate called Dia-Flat that is impregnated with diamonds at 120 microns. The diamonds are bonded to the plate using a proprietary technology called DMT Hardcoat Technology. They asked me to use the heck out of it and report back. So I used it. This is my report:
I’ve taken the stone with me all over the country these last few months and let students flatten all their oilstones and waterstones and who-knows-what stones. At Roy Underhill’s school some students brought in all their stones from home. We flattened every oilstone we could get our hands on in Roy’s shop.
And I’ve flattened my Shaptons about 200 times with the stone. So far, I love the thing. It is heavy, at four pounds, and big, at 4-1/4″ x 10″. The weight and size keep it on the stone and make it easy to hold.
The grit cuts fast and leaves a nice surface. And the thing is flat. DMT certifies it as flatter than .0005″ across its surface. That is way flatter than anyone needs.
How does the Hardcoat hold up? No clue. But Stan Watson, the technical director at DMT, is still using the stone from R&D on the product and says it is “far from worn out.” The Hardcoat technology is the real curious thing here, and I asked Watson about it in an e-mail.
“…(W)e went back to the drawing board with a clean slate and looked at ways to increase the life of a stone designed for the tortuous application of flattening another abrasive stone,” Watson wrote. “After several attempts, we devised a highly proprietary process that adds significant wear resistance to the matrix used to bond the diamonds to the steel substrate.”
So what is the coating made of?
“Sorry I can’t go into more detail about it,” he wrote. “Even Coca Cola has their secrets!”
DMT introduced the stone to the public last weekend at the Northeastern Woodworkers’ Association Showcase and will be available shortly – right now DMT is just working out the details on packaging and marketing.
The price? The suggested retail is $199.99, but Watson said that most retailers will discount it below the suggested retail.
I plan to buy one to replace my DMT Duo-Sharp stone that I have been using for 10 years. It still flattens my stones, though it is now quite slow.
We’ll see how the DMT Dia-Flat holds up, and I’ll report back in a couple years.
— Christopher Schwarz
• A good source for sharpening supplies, including DMT, is SharpeningSupplies.com.
• Ron Hock’s book “The Perfect Edge” is a great reference book on the topic.
• Want to learn to sharpen on sandpaper? Try Brent Beach’s site.