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Thread: Funny profile tolerancing with (U) must match the adjacent recess diameter tolerance!

  1. #1

    Funny profile tolerancing with (U) must match the adjacent recess diameter tolerance!

    I'm working on a part which has a recess diameter of 88.04 (+0.1, +0.3)mm. The adjacent flat surface must (because I want to understand the shenanigan) match the equivalent profile tolerance with the (U) option.

    (Sorry for image quality, some number "3" look like number "2")
    Is it possible to put a negative value with the (U) so it matches the diameter tolerance?

    Regards,

  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    Assuming the dimensioning and tolerancing standard in use is ASME Y14.5-2018 - Unilateral Profile tolerances start (defined from location) at the nominal location of the surface specified variation. There is not any reference to a - (negative) unilateral Profile tolerance within the standard.


    By default, Profile tolerances are bilateral equal unless otherwise specified.


    If the specification was 0.2 U 0 then the profile tolerance boundaries would be located starting at the nominal minus all 0.2 to the inside of that surface.


    If the specification was 0.2 U 0.2 then the profile tolerance boundaries would be located starting at the nominal plus all 0.2 to the outside of that surface.


    U = circle U


    See:
    ASME Y14.5-2018 Figure 11-31 and and referenced paragraphs
    ASME Y14.5-2018 Figure 11-2 and paragraphs 11.3.1.2, 11.2.1.1
    ASME Y14.5-2018 Figure 11-3 and referenced paragraphs
    ASME Y14.5-2018 Figure 11-4 and referenced paragraphs
    ASME Y14.5-2018 Figure 11-5 and referenced paragraphs
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

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