[BR...] Posted November 9, 2020 Share Posted November 9, 2020 I have a part with this true position callout on it. I have yet to see the true position called out twice to the same datum with it being the face. I have seen to ABC twice but not just the face. Not a hundred percent sure what they are asking here. It is a very simple part with basically the two callouts on a rectangular piece. I'm open to some ideas heretrue pos.jpg Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/ Share on other sites More sharing options...
[Am...] Posted November 9, 2020 Share Posted November 9, 2020 I'd have to see at least part of the drawing but this is called a composite true position one is going to be for the feature tolerance zone and the other for the pattern tolerance zone. Im gonna say there are probably two bores on a face, the top is the location of the bores and the bottom is going to be their position to each other. They could be in the right place to datum to meet the .014 but too close to each other and fail the bottom callout. What is Datum A in this case? Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73658 Share on other sites More sharing options...
[BR...] Posted November 9, 2020 Author Share Posted November 9, 2020 datum A in the bottom face Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73660 Share on other sites More sharing options...
[Ja...] Posted November 9, 2020 Share Posted November 9, 2020 My understanding is not that good. Here's something right from GeoTol Pro book that might help. "The upper segment controls location and orientation of features to specified DRF. The lower segment controls location and orientation between features but orientation only to specified DRF. " Here's some links to Tec Ease that might help. https://www.tec-ease.com/gdt-tips-view.php?q=128 https://www.tec-ease.com/gdt-tips-view.php?q=119 Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73662 Share on other sites More sharing options...
[SH...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. Can you upload Full drawing, can't visualise. Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73664 Share on other sites More sharing options...
[BR...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. in a nutshell this is the part. the true position call out is on the B datum hole and is 2x per the snip it i shared in the original. I cannot post the actual print for various reasonsIMG_0323.JPG Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73666 Share on other sites More sharing options...
[Jo...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. In that diagram all I can see is the first frame controls perpendicularity of B to A. The second frame without AB doesn't do anything afaik. There isn't a detail regarding counterbore to hole relationship is there ? Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73668 Share on other sites More sharing options...
[SH...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. 2x means pattern,so it should move in the same direction and centre distance is a part of true position. It looks like ABC alignment C is your second bore.But your datum reference frame is quite different. Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73670 Share on other sites More sharing options...
[Ja...] Posted November 9, 2020 Share Posted November 9, 2020 The specification is "invalid" in that the bottom requirement overrides that of the top. In the top specification (PLTZF), two .014 tolerance zones that are located at basic distance from one another and perpendicular to A must contain each axis. In the bottom specification (FRTZF), two .003 tolerance zones that are located at basic distance from one another and perpendicular to A must contain each axis. You can see that two axes satisfying the bottom requirement must satisfy the top requirement. The idea of the FRTZF translating within the PLTZF does not have any meaning here as the primary datum is a plane perpendicular to the tolerance zones (translation can't be determined). Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73672 Share on other sites More sharing options...
[BR...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. thank you, that is what was confusing the heck out of me. there aren't even dimensions on the print, other than the hole/c'bore callout and true position everything else is .020 profile to the model they provided. Link to comment https://qualityforum.zeiss.com/topic/14158-true-pos-to-one-datum/#findComment-73674 Share on other sites More sharing options...
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