Strange behaviour with datum system / parallel offset main datum

[[Jo...]]

Hello,

i am doing pretty basic stuff and getting unexpected results. I am hoping you might find what i`m doing wrong or confirm that the observed behaviour is not to be expected.

Building the datum system i get an parallel offset to the main datum A with the calculation method ISO 1101. With geometry it is looking as expected.

 

Depiction of the "unexpected behaviour":

Topview with surface comparison:

Sideview:

You can clearly see the parallel offset of plane A between part and CAD after aligment.

This should not happen in my opinion. The first 3 degrees of freedom of plane A should fix this no matter Geometry or Iso 1101 calculation.

 

Information (drawing and how the datum system is build):

 

 

Thanks in advance!

[[Ma...]]

If you want to be sure make surface profile for datum A to your ABC, then extract MIN/MAX from all points of profile callout - you should see in MAX 0.000

ISO/ASME makes datum A as tangential element.

[[Jo...]]

Ok, found the culprits. Got some dust on the part while spraying.

just my temporary blindness and working as intended.

@Martin

i trusted the surface comparision too much and got mislead. the way way you descibe is fool proof, thanks.