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True Position on holes?

How do I report CPU for True position on holes only since its a unilateral tolerance. I'm currently running Datapage/RT v 3.33, I need it to report CPU on the actual report. Is this possible? I tried just about every setting on the options but no luck. Any help towards the right path would be greatly appreciated.
  • When you say TP and unilateral, I am assuming you mean the tolerance is one sided, not unilateral. Anyway, TP as far as I know cannot give proper stat readings due to it being one sided. You can tolerance it by cutting it in half, it's not perfect, but ± .5 will give the proper stat info and it will be close.
  • Unilateral means all on one side. Bilateral means on 2 sides. All true position tolerances are unilateral, ie they can only be positive values.
  • How do I report CPU for True position on holes only since its a unilateral tolerance. I'm currently running Datapage/RT v 3.33, I need it to report CPU on the actual report. Is this possible? I tried just about every setting on the options but no luck. Any help towards the right path would be greatly appreciated.


    I'm assuming by CPU, that you mean the Cp value U. Since TP is positive, it should have a CpU value, but not a CpL value. But, a TP gives no indication of directionality (because it is a diametrical tolerance calculated by squaring. A squared number cannot be negative.)

    +/- half of your TP tolerance allows for out of tolerance conditions. Divide your TP tolerance by 2, and multiply that number by .7071 (cos 45 deg). This makes a tolerance zone that is circumscribed by the TP diametrical zone. So, good parts can show bad, but bad parts cannot show good.

    Either way, capability of a TP is worthless. As is capability of any unilateral tolerance (flatness, perpendicularity, parallelism, etc).