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

[joel_lapointe]

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.

Negative.PNG

(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,

[Kelly_Bramble]

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