Product Reviews

DMT Dia-Flat™ Lapping Plate

By Bob Duncan

When you sharpen gouges and V-tools using oil stones or waterstones, the tools can wear a groove into the stone, which makes it difficult to sharpen flat tools. That’s why it is important to flatten, or lap, your stones regularly.

To lap a stone, you need to use a second stone that is more abrasive and flatter than the one that needs to be flattened. Several stones are designed for lapping. Alternately, some people use coarse sandpaper or an abrasive paste on plate glass. However, after using the Dia-Flat™ Lapping Plate for a few stones, I won’t use anything else.

The Dia-Flat consists of an indestructible coarse-diamond coating on a heavy 4″ by 10″ plate, which should be large enough to flatten any stone. The plate is guaranteed flat to 5/10000″. The stone is abrasive enough that I flattened a cupped waterstone in five minutes; a cupped oilstone took just a few minutes more.

The Dia-Flat Lapping Plate is an investment at $212, but it will last a lifetime. Visit or call 800-666-4DMT to purchase one or to find a local retailer.

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