Scan results different from keyed-in points

I have a part with a very tight profile tolerance (form+location) of .0005. I wrote a program with a model and aligned to all 3 datums.

I keyed in gage points and read the vectors from the model. Part is out of tolerance (which I expected) by about .001, the profile being off center.

Next I added a linear TTP scan along the same section where I probed the gage points. The scan shows deviations up to .018!

Same program, same part, same alignment.

What could I be doing wrong with my scan to get a result that differs so much from my keyed-in points?

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UKCMM over 10 years ago

Yes that is why I stated the only place with a 0.470 radius is at the parallel section A - A . The part is bell/ trumpet shaped after the 0.333 cylinder and not a curve with a constant 0.470 radius along its edge as as stated by the OP.That is unless the drawing/sketch is not the same as what he is checking.
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UKCMM over 10 years ago

Yes that is why I stated the only place with a 0.470 radius is at the parallel section A - A . The part is bell/ trumpet shaped after the 0.333 cylinder and not a curve with a constant 0.470 radius along its edge as as stated by the OP.That is unless the drawing/sketch is not the same as what he is checking.
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