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Scraper |
Edge angles
The Scraper's cutting edge is formed by one step on the grinder. The grinding action forms the hook.
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Someday you will look back at this work, laugh nervously and change the subject. Unknown |
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General Guidelines |
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Relief |
Comments |
| 75° | 40° |
click on the gray block to see more Some recommend the use of a belt sander (i.e., one which is bolted to the bench, not a hand-held one). I've used that and the Tormek with the Tormek SVD-110 Tool Rest. Both work, but the Tormek grinds away less metal, so that is what I prefer. If you chose to grind a different angle, then use the following guidance when using the Tormek SVD-110 Tool Rest:
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If grinding this on a high speed grinder or sander, be sure to manage the temperature so that the temper is not lost due to overheating.
| High Carbon Steel |
Temperature control is critical for high carbon steel. Tempering will be lost in the steel if heated until it is blue (~550°F / 300°C). Cool by dipping as needed in water. Dr. Larrin Thomas noted in his book, Knife Engineering: Steel, Heat Treating, and Geometry (2025), The lack of sparks or color changes is no guarantee that the edge was not overheated. Therefore, sparks are not necessarily a sign that heat has or has not been generated in the steel. Color changes can occur from overheating of steel in grinding, but during grinding, the surface is being removed, and the affected volume can be relatively small. Therefore a color change is not always observed. Microhardness measurements of edges sharpened with a belt sander show a drop in hardness at edge. This results from “over-tempering” the edge by heating it above its original tempering temperature. |
| High Speed Steel |
Cool by dipping as needed in water. |
| Steel with Carbide Insert |
DO NOT cool by dipping in water. This will cause the carbide to crack due to shocks.
It is also recommended to use a high grit wheel for sharpening carbide as lower grits can cause cracks in the edge leading to it being far more crack-ridden and brittle. (Lower grits can be used for shaping the edge -- see also, Grindstones and Other Sharpening Media - Quick Selection Guide.) |
