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Vector Deviations gone awry

mjdevries
I received data from a PC-DMIS cmm and was reviewing it. We receive the data with the XYZ and the Vector deviation information. I was reviewing this data and I noticed that the vector deviation was much larger than the sqrt of the sum of the squares of the coordinate deviations, AKA, the absolute deviation. I reviewed the PC-DMIS program and found that the nominal in the CALL/EXTERN statement did not match the feature declaration statement which defines the nominals that are used in the X, Y, and Z outputs. I'm assuming the CALL/EXTERN statement defines the vector measurement from the nominal point in the call statement. Does this make sense?

F(M1)=FEAT/POINT,CART,590.878, -687.587,662.998,0.0459841,-0.998654,0.0239917
CALL/EXTERN,DMIS,M(PCD_AUTO_VECTOR_POINT_605),(M1),590.878, -690.59,$
662.998,0.0459841,-0.998654,0.0239917,VEC,0.0459841,-0.998654,0.0239917,$
0.0459841,-0.998654,0.0239917,'THEO_THICKNESS',0,'NO','NO',0
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  • Any deviation reported should be from the Nominal and not the Target coordinates. The Target is only used in PC-DMIS to control probing path and measurement hit locations. Also, the vector deviation results should be calculated along the Nominal vector.

    Unfortunately, this does not explain why the vector deviation you see is LARGER than the absolute deviation.
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  • Any deviation reported should be from the Nominal and not the Target coordinates. The Target is only used in PC-DMIS to control probing path and measurement hit locations. Also, the vector deviation results should be calculated along the Nominal vector.

    Unfortunately, this does not explain why the vector deviation you see is LARGER than the absolute deviation.
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