Abbe's Principle [PDF]

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Abbe’s principle • maximum accuracy may be obtained only when the standard is in line with the axis of the part being measured



Abbe’s principle



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Vernier calliper



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Micrometer



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Abbe offset • distance between the desired point of measurement and the reference line of the measuring system



Lm dy



To measure this length



Abbe offset



Lt



eA



Lm



Lt



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Example



Bryan principle 1979



• In a vernier caliper, the object is kept 50 mm away from the beam. The moving jaw is misaligned with the fixed jaw by an angle of 0.1o. Compute the Abbe error. • 0.087 mm



• The displacement measuring system should be in line with the functional point whose displacement is to be measured. If this is not possible, either the slideways that transfer the displacement must be free of angular motion or angular motion data must be used to calculate the consequences of the offset.



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Bryan principle 1979... • Similarly the straightness measuring system should be in line with the functional point whose displacement is to be measured. If this is not possible, either the slideways that transfer the displacement must be free of angular motion or angular motion data must be used to calculate the consequences of the offset. 01/11/2020



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