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Because sharp enough ... usually is not |
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Ground vs. Effective Angles
The angle with which the cutting tool is presented to the object can change the effective angle for the way a tool works (e.g., the relief or clearance angle). The diagram to the right shows a typical configuration for a cutoff tool.
Presentation Angle - It is typical to present a cutoff tool at an upward angle. For this example, we'll use 5°.
Effective Angle - This is the effective angle of the cutting, relative to the object's centre line. For a cutoff tool, the relief angle is typically around 7°, so that is what we will use for this example.
Ground Angle - The Ground Angle is the sum of the Effective Angle (5°) and Presentation Angle (7°). For this example, this would be:
5° + 7° = 12°
So, in this example the machinst would grind the tool with an angle of 12° relative to the top of the tool.