PR 242091 The Perpedicularity of a middle plane is always zero.

huangyhg

<< Domenico Varacalli  --  07/25/06  18:52:00>>
The Perpedicularity of a middle plane with a Datum A is always zero. Why?
Note: the middle plane PLN4 is not normal to the Datum "A" because the other two planes (PLN2, PLN3) are enough tilted.
In the example I have exaggerated the inclination.

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<< Changes made by Neil Kay -- 12/12/08  09:27:39>>
Action:  Don Turcotte to Yanhua Huang
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<< Changes made by Neil Kay -- 07/22/08  19:26:22>>
Action:  Paola Pallo to Don Turcotte
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<< Domenico Varacalli  --  07/27/06  10:05:19>>
There is however to make a consideration. (look at the PDF file, mid_line.zip)
In the new attached example, I have measured the perperdicularity of a middle line with a Datum [A] and the perperdicularity of a middle plane with the same Datum [A].
In the 1st case (MiddleLine = LIN3) the results seem correct and reliable. LIN1 Meas = 1.426   LIN2 Meas = 0.710   LIN3 Meas = 1.068
In the 2nd case (MiddlePlane = PLN4) the result is "0". PLN2 Meas = 0.026   PLN3 = 0.012   PLN4 = 0.000
My question is: why the calculation of perperdicularity (for example) it works for the middle line and not for the middle plane?
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<< Don Turcotte  --  07/26/06  17:20:37>>
Perpendicularity of a plane (as well as Parallelism and Angularity) use the measure points of the plane to compute the tolerance deviation.  The tolerance represents the distance between two parallel planes that are at the nominal (theo) orientation and contain all the measure points.  
Since a constructed feature has no measure points, orientation dimensions on constructed features will always report 0 deviation.  The alternative is to use 3D angle between with a nominal of 90 but this reports angular deviation and the tolerance value is an angular tolerance.
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<< Changes made by Don Turcotte -- 07/26/06  17:20:47>>
Action:  Don Turcotte to Paola Pallo, Status:  OPEN to REVIEW
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<< Changes made by Tim Wernicke -- 07/25/06  13:18:15>>
Action:  Paola Pallo to Don Turcotte, Assigned:  Paola Pallo to Don Turcotte, Priority:  to High
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