The SP-650 Stone Grader is one of the most unique features of the Tormek Sharpening System. The stone grader is used to change the grit of the Grindstone from a coarser 220 grit to a fine 1000 grit wheel. This unique system allows you to use the same high quality Tormek Grindstone for dual purposes without removing the stone.
The grading of the grindstone is made by pressing the fine side of the Stone Grader onto the grindstone, which makes it work as a fine grit stone (approx. 1000 grit). When pressing the coarse side onto the grindstone, the smoothed surface is returned to its normal condition (220 grit). This process does not place excessive wear on the grindstone and can be repeated any number of times.
The stone grader is included with both the T8 and T4 models. It can be used with the standard stones for either model as well as the Blackstone for the T8 / T7. However, only the fine side should be used with the Japanese Water Stone for the T7 / T8 or the Japanese Water Stone for the T4. The coarse side should not be used on the Japanese Water Stones.