Edge Angle
Guidelines shown below are for the cutting edge angle.
Frequent sharpening is recommended to maintain the tool's shape, and is needed for safe performance of the tool.
In opposition to wood chisels, the wider the tool, the greater the angle.
- Claw tools also use a sharper angle, in the lower end of the range (as they are basically multi-point tools).
- Wide chisels use a less sharp angle, in the upper end of the range
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I saw the angel in the marble and carved until I set him free.
Michelangelo
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General Guidelines
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Material
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β
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Sharp
ness
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Comments
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Softer stone
(e.g., chalk, soapstone, & pumice)
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25° - 35°
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General stone
(e.g., limestone & marble)
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30° - 40°
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Harder Stone
(e.g., granite & basalt)
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40° - 60°
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Carbide inserts are usually embedded in the tips of these tools.
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Notes & Comments
Use larger angles for roughing out, and sharper (more acute) angles for finishing cuts.
Special Notes for Tools with Carbide Inserts: Do not cool by dipping in water : this will generate shocks in the metal, and cause the carbide to crack.
When sharpening, one of the following options is recommended.
- Leave corners slightly beveled, or
- Edge up on the final grind.
- Leave the final 1.5 mm (1/16 inch) unground. This is because the rough grinding of the carbide introduces cracks and makes the edge more brittle. By stopping short of the edge, this is minimized.
- Then, use a high grit wheel should be used to make the edge smooth with minimal cracks.
- A very high grit grindstone should be used if a very smooth carving surface is needed, or if the material is very soft.
Special thanks to Oleg Lobykin at StoneSculpt - Custom Stone Carving for providing the guidance.
