Rmeas help

I've been trying to figure out what PC-DMIS does with the RMEAS statement with the different numbers of Hits. I found some info that refers to the Rmeas with 3 hits as the "Flush/Gap" measurement. Can anyone explain the difference between the RMEAS with 1 hit versus the RMEAS with 3 hits? From analyzing the data I believe it has to do with the vector that is used when it takes the actual measurement. From what I've seen looking at data is the single hit RMEAS would be considered a "Surface/Edge" measurement where the edge is too thin to consider it having any thickness/depth.

From my own analysis it appears that the single hit version uses an approach vector that is perpendicular to the reference points vector. The vector I believe is derived by the unit vector of (|V1| X |V2|) X |V1|, where V1 is the vector on the surface point and V2 is the vector on the point being measured with RMEAS. The X represents the Cross Product function. The first cross product is done between the 2 vectors to obtain a vector normal to the 2 vectors. The cross product of the resulting vector & the surface vector then gives you a vector that is perpendicular to the surface vector V1, but in the same plane as V2.

Does anyone know what the 3 hit version does?

F(F0954M009B) = FEAT/POINT,CART,2531.99,860.834,605.15,0.0437,0.9651,0.2584
  MEAS/POINT, F(F0954M009B), 1
  ENDMES
 T(XTOL_4)=TOL/CORTOL,XAXIS,0.0,0.0
 T(YTOL_4)=TOL/CORTOL,YAXIS,-0.15,0.15
 T(ZTOL_4)=TOL/CORTOL,ZAXIS,0.0,0.0
 T(VECTOL_4)=TOL/PROFP,0.0,0.0
 TEXT/OUTFIL,'F0954M009B - POINT - INSP=D METAL=0.686'
 OUTPUT/FA(F0954M009B),TA(XTOL_4),TA(YTOL_4),TA(ZTOL_4),TA(VECTOL_4)

  GOTO/2536.032,864.531,605.704
F(G0954M009B) = FEAT/POINT,CART,2524.03,857.084,605.007,0.9667,-0.2002,-0.1595
  RMEAS/POINT, F(G0954M009B), 1, FA(F0954M009B)
  ENDMES
 T(XTOL_5)=TOL/CORTOL,XAXIS,-0.15,0.15
 T(YTOL_5)=TOL/CORTOL,YAXIS,0.0,0.0
 T(ZTOL_5)=TOL/CORTOL,ZAXIS,0.0,0.0
 T(VECTOL_5)=TOL/PROFP,0.0,0.0
 TEXT/OUTFIL,'G0954M009B - HEDGE - INSP=D METAL=0.686'
 OUTPUT/FA(G0954M009B),TA(XTOL_5),TA(YTOL_5),TA(ZTOL_5),TA(VECTOL_5)
  GOTO/2536.032,864.531,605.704

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mjdevries over 11 years ago

They are trying to use the edge measurement here for measuring the edges of bent corners. This would be more of a bent corner. I believe the the 'Theo Thickness' and the 'Edge Theo Thickness' may be dependent on the surface vector of the cad where the edge point is defined. The sketch you posted is for a trim edge where the cad design is flat surface that gets thickened, so the design vector of the surface that the edge point is on would be perpendicular to the edge you want to measure. The edge measurement does not use the vector on the edge point for the approach. It does some math where it finds the vector that is perpendicular to the surface point and uses that for the approach. Which in the sketch you drew, would still be normal to the edge surface.

With that in mind I think that the design I am looking at where the design surface is bent and the edge point is on a surface with a vector the 'Theo Thickness' and 'Edge Theo Thickness' would be like this sketch. This would give me the results that I am seeing where the actual measurement points are all skewed because the hit is being taken where the 'Edge Theo Thickness' point is shown.
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mjdevries over 11 years ago

They are trying to use the edge measurement here for measuring the edges of bent corners. This would be more of a bent corner. I believe the the 'Theo Thickness' and the 'Edge Theo Thickness' may be dependent on the surface vector of the cad where the edge point is defined. The sketch you posted is for a trim edge where the cad design is flat surface that gets thickened, so the design vector of the surface that the edge point is on would be perpendicular to the edge you want to measure. The edge measurement does not use the vector on the edge point for the approach. It does some math where it finds the vector that is perpendicular to the surface point and uses that for the approach. Which in the sketch you drew, would still be normal to the edge surface.

With that in mind I think that the design I am looking at where the design surface is bent and the edge point is on a surface with a vector the 'Theo Thickness' and 'Edge Theo Thickness' would be like this sketch. This would give me the results that I am seeing where the actual measurement points are all skewed because the hit is being taken where the 'Edge Theo Thickness' point is shown.
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