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DMT Dia-Flat™ Lapping Plate

User Rating: 5 / 5

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The new Dia-Flat® Lapping Plate from DMT (Model DIAFLAT) is a remarkably flat and accurate surface of monocrystalline diamonds used to flatten other sharpening stones, and waterstones in particular.




I found the instructions to be very clear. We began by making a cross hatched set of marks on the face of my test waterstone (which was already supposed to be flat) with a pencil.The Dia-Flat® proverd to be superior to my old system making the waterstone even flatter and better than it was before. I put the test waterstone in a sink with constant slow running water directed over it and went to work with the Dia-Flat®. The stone was found to have a dish in the middle according to the marks left after a few passes with this ultimate flattening tool, and after a few minutes of work it was flat and ready to be used again re-sharpening my tools. I found that after flattening my stones I got better and faster results and a quick re flattening after each use of the stone was the best way to optimize performance.

I exclusively use Naniwa CHOSERA stones, finding them better than the Shapton stones in my experience, and now with the new DMT Dia-Flat® the stones are as flat as their first use which is key. What makes the Dia-Flat® so good? Well first it is wider than the waterstones and it is big and heavy (10” x 4” x 3/8”). It is aggressive but not overly so and it is flat to within .0005” over its entire length. I use six stones when sharpening and step from 400 to 12000 grit which leaves a mirror finish on the blades bevel. I was happy to find that with the stones flatter I only spent about half the time sharpening with them and the results were superior.

At $199 this tool is not cheap but it makes up so much valuable time in the shop it pays for its self in the first couple of months and then keeps on giving. I also used it to flatten my old oil stones and it made quick work of them. While I rarely use the oil stones from my grandfather’s kit, it’s nice to know they are flat should I want to use them to sharpen a tool. Look, if you’re like me you have spent thousands on stones and machines trying to achieve the fastest superior edge you can get on a tool. I want great results because anything less and you’re not getting the most from your $600 smoothing plane or your new sweetheart chisels. If you want to raise your game to the next level you need this lapping plate. I am very happy to recommend this tool to you as an editor’s choice and a 5 out of 5 star winner. It is a best buy at only $199 and it is a tool that will last you for many years to come.

In the process of researching this I read a review where a guy tried to flatten a carborundum (silicon carbide) stone and damaged his lapping plate. The problem being carborundum is almost hard as diamond and he should have done a test first to see if it would flatten without damage. I think he made a huge error and then gave this tool a bad review based upon the result of his own error. I have never seen a carborundum stone dish because they are so hard. I think if he had actually asked, DMT may have taken care of the stone for him but he didn’t ask so he is angry at himself. I wonder how long he had to rub the stone to wear the diamond plate smooth as glass? You know it was not quick, you’re talking diamonds and carborundum. People do some of the silliest things then blame a great product for their own stupidity. It kills me. THEREFORE, if you want to flatten a carborundum stone use sand paper and a flat granite block. You will go through the paper like mad but it is better than destroying a $200 lapping plate.

After the initial re-flattening it only takes 30 seconds at the most to re flatten the Naniwa stones and I do it right after I am done so I am ready to go on my next time to sharpen. So the bottom line is this is a great tool and yes it is possible to be misused, but used correctly it will serve you for many years and at $199 it will give you a much better level of performance from your pricy water and oil stones. The tool is so good it gets an editor’s choice award. I will use it for the next couple of years and will post an update on how long it lasts under proper use.

Product Information:

The Dia-Flat™ is designed to flatten all oilstones and waterstones. Certified flat to +/-0.0005” and coated with the revolutionary DMT® Diamond Hardcoat Technology™, the 120grit aggressive diamond coating makes short work of not only flattening any conventional oilstone or waterstone, but with a lighter touch, is also the go-to tool for maintaining your stones as well.

  • DMT® Diamond Hardcoat Technology™
  • Designed for use on all conventional oilstones and waterstones
  • Flat to +/-0.0005
  • Large 10" x 4" surface




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