37 lines
1.0 KiB
Plaintext
37 lines
1.0 KiB
Plaintext
There are three components to the radius error tolerance for center-format
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arcs.
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The "absolute error" is the difference between the radius at the starting
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point and the radius at the ending point. The "relative error" is the
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absolute error divided by the maximum arc radius.
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The absolute error threshold for imperial arcs is:
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2 * 0.001 inch * sqrt(2)
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The absolute error threshold for metric arcs is:
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2 * 0.01 mm * sqrt(2)
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The relative error threshold for all arcs is 0.001 (0.1%)
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An arc fails the radius tolerance test if either of these conditions
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is true:
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* The absolute error is greater than 100 * the absolute error
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threshold,
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OR
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* The absolute error is greater than the absolute error
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threshold AND the relative error is greater than the relative
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error threshold.
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This yields three error regions:
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r_big < t_abs/t_rel (2.828 inch or 28.28 mm ): r_small > r_big - t_abs
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r_big < 100 t_abs/t_rel (282.8 inch or 2828 mm): r_small > (1-t_rel) r_big
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r_big > 100 t_abs/t_rel: r_small > r_big - 100 t_abs
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