[SH...] Posted June 7, 2021 Share Posted June 7, 2021 For checking this flatness should I go for symmetric plane or symmetry construction?. Perfect form required at MMC condition, but here print says at MMC flatness is 0.3 so it is violating rule number 1?. What should be the size of snap gauge, 20.2 or 20.5?IMG_20210607_215314.jpg Link to comment Share on other sites More sharing options...
[Ma...] Posted June 7, 2021 Share Posted June 7, 2021 Is this even valid? Link to comment Share on other sites More sharing options...
[Cl...] Posted June 7, 2021 Share Posted June 7, 2021 This is wrong, MMC cannot be applied here. Use a symmetry plane (recalled points from both planes) Link to comment Share on other sites More sharing options...
[SH...] Posted June 7, 2021 Author Share Posted June 7, 2021 I think there may be some exceptions to rule number one. I have to verify the standard. Link to comment Share on other sites More sharing options...
[Ro...] Posted June 7, 2021 Share Posted June 7, 2021 A Derived median plane is a feature of size and can have MMC. The MMC callout overrides Rule 1. Link to comment Share on other sites More sharing options...
[Jo...] Posted June 7, 2021 Share Posted June 7, 2021 Please sign in to view this quote. Could you use profile of surface for second plane back to Datum A ? bilateral tolerance of .4 . Then flatness of both planes not to exceed .3 RFS . I think that would satisfy drawing intent. Link to comment Share on other sites More sharing options...
[Da...] Posted June 7, 2021 Share Posted June 7, 2021 I've never heard of taking points from both planes and using a flatness callout for the resulting median plane. How does that work? Link to comment Share on other sites More sharing options...
[Da...] Posted June 7, 2021 Share Posted June 7, 2021 Flatness is form only, no datums, no modifiers. I think its safe to say that the placement of the flatness on the dimension, and not attached to one surface is also a mistake. The way calypso makes symmetry features it will not have any form errors, If I'm not mistaken ? Link to comment Share on other sites More sharing options...
[Ma...] Posted June 7, 2021 Share Posted June 7, 2021 I found some article for this https://www.linkedin.com/pulse/flatness ... dan-pepin/ Link to comment Share on other sites More sharing options...
[Cl...] Posted June 7, 2021 Share Posted June 7, 2021 Please sign in to view this quote. I thought a symmetry plane could be used to evaluate flatness. Your right, doesn't work. Calypso won't allow you pull the feature into the characteristic. Although It does work in either a form & profile characteristic. Link to comment Share on other sites More sharing options...
[Da...] Posted June 7, 2021 Share Posted June 7, 2021 Martins article sheds some light on the idea, but at the end, the correction uses the flatness callout on one surface. Link to comment Share on other sites More sharing options...
[SH...] Posted June 8, 2021 Author Share Posted June 8, 2021 So, in CMM can't check this flatness?. Link to comment Share on other sites More sharing options...
[Me...] Posted June 8, 2021 Share Posted June 8, 2021 Just simulate a functional gage by reporting the width of the outer tangential symmetry plane. The reported width must be less than or equal to the virtual condition. If you’re using the latest release of Calypso, you can report the local size using the 2-Point distance characteristic set to “LP”. Doing each of these will “satisfy” both requirements. If you must report an actual flatness value, then you’re going to need to create a rather large number of midpoints and construct a plane from them in order to use the flatness characteristic. Link to comment Share on other sites More sharing options...
[Ri...] Posted June 9, 2021 Share Posted June 9, 2021 Please sign in to view this quote. Link to comment Share on other sites More sharing options...
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