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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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  • From your post, I am unable to determine why the Target is different from the Nominal values. I can see that SNAP is disabled, and no thickness offset is applied to the measurement.

    What does PC-DMIS do if your target and nominals are different in terms of the output. Assuming that the nominal was correctly entered and the target was incorrect would this affect only the profp when output is generated with the output statement like below. Would the X, Y, Z coordinates still reflect deviations from the nominal and not the target?

    T(LOC1__X)=TOL/CORTOL,XAXIS,-0.7,0.7
    T(LOC1__Y)=TOL/CORTOL,YAXIS,-0.7,0.7
    T(LOC1__Z)=TOL/CORTOL,ZAXIS,-0.7,0.7
    T(LOC1__T)=TOL/PROFP,-0.7,0.7

    OUTPUT/FA(M1),TA(LOC1__X),TA(LOC1__Y),TA(LOC1__Z),TA(LOC1__T)

    This stems from me receiving data that is showing XYZ coordinate deviations and profile deviations that are not relatively correct. Basically I have results for the Profile that are larger than the calculated deviation from nominal using the X,Y,Z coordinates and the correct nominals.
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  • From your post, I am unable to determine why the Target is different from the Nominal values. I can see that SNAP is disabled, and no thickness offset is applied to the measurement.

    What does PC-DMIS do if your target and nominals are different in terms of the output. Assuming that the nominal was correctly entered and the target was incorrect would this affect only the profp when output is generated with the output statement like below. Would the X, Y, Z coordinates still reflect deviations from the nominal and not the target?

    T(LOC1__X)=TOL/CORTOL,XAXIS,-0.7,0.7
    T(LOC1__Y)=TOL/CORTOL,YAXIS,-0.7,0.7
    T(LOC1__Z)=TOL/CORTOL,ZAXIS,-0.7,0.7
    T(LOC1__T)=TOL/PROFP,-0.7,0.7

    OUTPUT/FA(M1),TA(LOC1__X),TA(LOC1__Y),TA(LOC1__Z),TA(LOC1__T)

    This stems from me receiving data that is showing XYZ coordinate deviations and profile deviations that are not relatively correct. Basically I have results for the Profile that are larger than the calculated deviation from nominal using the X,Y,Z coordinates and the correct nominals.
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