[Cl...] Posted February 26, 2020 Share Posted February 26, 2020 I have .393 Ø cylinder x 4.5" long. Datum -A- is the.311 Ø ID for 2.71" min. My base alignment is a 3d line from two (OD) circles at either end of the part, which is used for the Spatial X+/YZ origin. The flat at the X- end of the part is my X origin. At the X+ end of the part, the customer wants .002 true position of a YZ (ID) hole back to -A-. I measure the part, result is good. I rotate the part (around -A-) 90 degrees, run it again, it fails. Not by much, but why? The BA should follow the rotation of the part? Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/ Share on other sites More sharing options...
[Am...] Posted February 26, 2020 Share Posted February 26, 2020 Are the Styli used making contact in an unintended way when the part is rotated 90°? Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90526 Share on other sites More sharing options...
[Cl...] Posted February 26, 2020 Author Share Posted February 26, 2020 Nope, all the surfaces being probed are, smooth, clean, no burrs, with good form. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90528 Share on other sites More sharing options...
[Er...] Posted February 28, 2020 Share Posted February 28, 2020 What measuring strategy are you using to establish Datum A? Are they Full circles? Are you scanning or taking points, and how many points? Are you using the same measuring strategy with the ID? When you check the position, are you checking the ID to the 3d line? Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90530 Share on other sites More sharing options...
[Cl...] Posted March 2, 2020 Author Share Posted March 2, 2020 For -A- I've tried linear scans, circles, different lengths. Tried different probes. Tried laying the part both horizontally and vertically. Tried a different CMM. All those give out of tolerance results.Test indicator, and roller gage shows a good part. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90532 Share on other sites More sharing options...
[Br...] Posted March 2, 2020 Share Posted March 2, 2020 Clarke, In the same vein as Eric's questions... What does your form error look like on the (2) circles that make up your 3D line? On your ID Hole, what is the form error look like (if an ID cylinder look at the A1 & A2 values as well)? I always review my datum(s) and features for measurement error before rejecting or accepting a part. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90534 Share on other sites More sharing options...
[Cl...] Posted March 2, 2020 Author Share Posted March 2, 2020 The form on every feature involved is .0001/.0002. My next step is to create -A- as a 3d line instead of a cylinder. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90536 Share on other sites More sharing options...
[Cl...] Posted March 2, 2020 Author Share Posted March 2, 2020 Constructed Datum -A- as a 3d line instead of a cylinder. Now when I rotate the part, it repeats w/in 10ths. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90538 Share on other sites More sharing options...
[Ow...] Posted March 2, 2020 Share Posted March 2, 2020 Right or wrong, many experienced users feel this. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90540 Share on other sites More sharing options...
[Ke...] Posted March 2, 2020 Share Posted March 2, 2020 Please sign in to view this quote. Out of curiosity, what was the Form of the Cylinder? Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90542 Share on other sites More sharing options...
[Cl...] Posted March 2, 2020 Author Share Posted March 2, 2020 A two circle cylinder. One of the circle paths had a form error of .0006". Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90544 Share on other sites More sharing options...
[Ti...] Posted March 8, 2020 Share Posted March 8, 2020 From what I remember in training was not to use a cylinder for alignment and be careful with using constructed features for alignment. Is this true or false? Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90546 Share on other sites More sharing options...
[SH...] Posted March 9, 2020 Share Posted March 9, 2020 Please sign in to view this quote. Then what we should use instead of cylinder 3D line??. Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90548 Share on other sites More sharing options...
[Ti...] Posted March 10, 2020 Share Posted March 10, 2020 That is what I have used when having an alignment problem with cylinders Link to comment https://qualityforum.zeiss.com/topic/16316-rotate-part/#findComment-90550 Share on other sites More sharing options...
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