[Ky...] Posted June 19, 2020 Share Posted June 19, 2020 We have a plate that is 35" X 25 " x .75" the plate has a .05 bow/twist. Datum A is top. Datum B is long edge. Datum C is short edge. Position of holes in plate is between .028 and .056. We are getting position showing to be between .003 and .005. Should the flatness of datum A throw off the true position or am I thinking about this wrong. The other inspectors and I are going " There is know way the holes can be this close with the Datum A not being flat" Link to comment https://qualityforum.zeiss.com/topic/15444-true-position-question/ Share on other sites More sharing options...
[Ja...] Posted June 19, 2020 Share Posted June 19, 2020 Are the holes positioned to [A|B|C]? If datum feature A has a lot of form error, your holes will probably not be very perpendicular to your derived primary datum plane, and thus throw the position out. How are you evaluating the plane? Least squares/Outer tangential? How are you probing/scanning? Link to comment https://qualityforum.zeiss.com/topic/15444-true-position-question/#findComment-83478 Share on other sites More sharing options...
[Ky...] Posted June 19, 2020 Author Share Posted June 19, 2020 Sorry for the delay. Yes the DRF call out is ABC. Evaluation of plane is LSQ. And we are scanning around outside edge of Datum Plane. And that is kinda the question, the position of the holes are showing to be real close to zero. Not off like we thought they would be. Link to comment https://qualityforum.zeiss.com/topic/15444-true-position-question/#findComment-83480 Share on other sites More sharing options...
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