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Spear Point Tool |
Side view |
Top View |
The Spear Point Tool's cutting edge is sharpened using a platform jig such as the Tormek SVD-110.
SVD-110 Platform Jig |
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General Guidelines |
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Angle |
Recom. |
Comments |
| α1 | 40° |
I've measured angles on tools in the range 35° to 80°, but 40° works well for me. |
| α2 | 40° |
The top angle needs to be <90° so that the tool can be used as a scraper for corners, though I've measured angles on tools which range from 60° - 95°. |
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. |
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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.) |
