Dieter Schmid's Fine Tools

What can one expect from Diamond Sharpening Stones, and what not?

Diamantschleifplatte Atoma Economy

One of the most common arguments for using diamond sharpening plates is that they are flat and do not become hollowed out during their working lives. The first point is only partly true, as the flatness of the plates depends a great deal on the quality of, and the method used to manufacture the plate. But it is true that they do not become hollow in use, like other kinds of sharpening stones do.

There are a number of different methods for producing diamond sharpening plates:

  1. A block of aluminum or steel is machined flat and then impregnated with diamond chips. This method can produce the flattest surface. The disadvantages are the expense of this method and the difficulty of the process, and relatively high material costs. So this method is not often employed.
  2. Thin steel plates are impregnated with diamond chips. These thin plates are then glued to a flat block, usually aluminum. Here the different cutting, machining and polishing methods become important to the end results. If a laser is used, for instance, the heat of the process can deform the metal plates. These deformations can have a bad effect on the final product and can only be corrected by a powerful press when mounting the thinner diamond plate to the base. So other methods of cutting and machining the base plates are often better. The thinner the diamond-surfaced plate, the easier it is to mount flat on a flat base plate.
  3. A plastic or copper foil is impregnated with diamond chips, and the back is coated with adhesive. These foils are very flexible and can be glued onto a variety shapes and base materials to fit your needs and ideas. One of the downsides with these foils is that they are delicate and when sharpening tools and blades, it is easy to catch an edge or corner and cut through the delicate foil, ruining the surface in that area, at least.

We sell diamond sharpening plates both with and without base plates because our customers have such a variety of needs and ideas. When one is often working on the road, for instance, the weight and volume of tools becomes an important consideration, and one can just use the thin diamond plates without the base plate. But this will inevitably result in a sharpening surface less flat than it could be. We also offer diamond-coated copper foils, which are very flexible and have an adhesive back.

Advantages of Diamond Sharpening Plates:

  • They allow quick removal of material for grinding out chips and changing the base bevel of plane irons and chisels.
  • Quick sharpening and material removal, also in the medium grit sizes is another advantage.
  • Sharpening HM-, HSS- und PM-steels, which are difficult or impossible to work using other types of stones, is possible.
  • The stones mostly keep their original shape, unlike other stones that wear with use and must be periodically re-flattened.
  • They can also be used as flattening blocks for Japanese water stone. We recommend the 400 grit plate for this application.

Disadvantages of Diamond Sharpening Plates:

  • When you need a very flat surface for really precise sharpening jobs, a freshly flattened Japanese water stone works better.
  • For honing, or putting a final clean edge on a tool, diamond sharpening plates are clearly not as good as sharpening stones because they simply cannot be made in the finer grit sizes.
  • With a diamond plate you cannot leave a mirror finish on a blade, on knife blades for instance.

One more point about useful working life with diamond plates. They cannot really be compared with sharpening stones, which are worn down in use, constantly revealing new, sharp particles. Diamond plates are much more like sandpaper, with a thin layer of abrasive fixed to a non-abrasive material. The diamond sharpening plates of course have a much longer working life than sandpaper, but the evolution is the same. At first they feel very sharp indeed, but just for a short time and then there is a very long period of medium-sharpness, and then at the end they don't really cut much at all. Be careful to buy plates with monocrystaline diamonds as this middle sharpness period will last much longer. Keeping the surface of the diamond plates wet will also prolong their useful life!

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