[Cl...] Posted November 9, 2021 Share Posted November 9, 2021 Question to the experts. I have a part 170mm long 6.00mm Ø (some areas smaller). The customer drawing calls out true position at various locations on the shaft, but are open to changes because of bad repeatability from a previous program strategy. The only datum is -A- which is the 6.00mm OD. The tip of the part is split down the middle lengthwise for 25.00mm and they want it's position as well. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/ Share on other sites More sharing options...
[Da...] Posted November 9, 2021 Share Posted November 9, 2021 Can you make a crayon sketch ? How long is the 6 MM ? Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57708 Share on other sites More sharing options...
[Da...] Posted November 9, 2021 Share Posted November 9, 2021 Use the centerline of the split as datum B and the end of the shaft as C. Check all cylinders that are .600 and recall them into a cylinder for A. Also check the A cylinders for coaxiality. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57710 Share on other sites More sharing options...
[Cl...] Posted November 9, 2021 Author Share Posted November 9, 2021 Please sign in to view this quote. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57712 Share on other sites More sharing options...
[Cl...] Posted November 9, 2021 Author Share Posted November 9, 2021 This should be simple, but I'm not sure that true position is the right way to evaluate this?Concentricity, runout? I do not know the function of the tool. All diameters and slot true position to -A- no MMC/LMC modifiers. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57714 Share on other sites More sharing options...
[Ch...] Posted November 9, 2021 Share Posted November 9, 2021 True position will give you the same answer as concentricity. For ISO and in Calypso, concentricity is just a special case of position in which both features share the same axis. David is spot on about making your Datum A as long as possible. You want to eliminate as much projection error as possible. Concentricity was obsoleted in the latest Y14.5 release in favor of position or runout. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57716 Share on other sites More sharing options...
[Cl...] Posted November 9, 2021 Author Share Posted November 9, 2021 Please sign in to view this quote. Forgot about concentricity being obsolete. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57718 Share on other sites More sharing options...
[Je...] Posted November 9, 2021 Share Posted November 9, 2021 . Clarke, I'd recommend the DRF mentioned above with runout as the characteristic to control the feature of interest. Runout controls form, orientation and location. You can simultaneously evaluate wobble, roundness issues and axis offset. Runout works great not just for rotating parts but any coaxial features of size. Jeff Frodermann Meier Tool & Engineering Anoka, Minnesota Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57720 Share on other sites More sharing options...
[Ch...] Posted November 9, 2021 Share Posted November 9, 2021 Please sign in to view this quote. My prediction: designers will still be putting concentricity on prints for another 20-30 years. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57722 Share on other sites More sharing options...
[Ow...] Posted November 10, 2021 Share Posted November 10, 2021 Please sign in to view this quote. You know it! However, what about Coaxiality which uses the same symbol? Seems like most newer prints I work with just use non-fully defined profile characteristics on 80-90% of everything...smh Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57724 Share on other sites More sharing options...
[Cl...] Posted November 10, 2021 Author Share Posted November 10, 2021 Please sign in to view this quote. I (we) agree, that was our final decision. Link to comment https://qualityforum.zeiss.com/topic/11644-true-position-or-concentricity/#findComment-57726 Share on other sites More sharing options...
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