ASME Y14.5-2018 Fundamental Rule q

[AndrewTT]

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4.1 (q) - UOS by a drawing/model note or reference to a separate document, the as-designated dimension value does not establish a functional or manufacturing target.
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Does anyone know the story behind why this rule was added? What problem is this rule solving?

 

[Belanger]

Andrew -- I suspect it comes from the common confusion about plus/minus tolerances which are unilateral or unequal bilateral.

Example: for the dimension
24 +0.3/-0.1
many people mistakenly think that 24 is the designer's intended target. Apparently ASME is now emphasizing that that isn't true. Manufacturing can aim for whatever number they want. It's all about getting the ball through the uprights.

 

[Hallec]

It's almost like it's saying, "A dimension does not necessarily indicate the correct, uhh dimension, for the dimensioned feature!" - So, I'm like.... What??

I'm not a vegetarian because I dislike meat... I'm a vegetarian because I HATE PLANTS!!

 

[aniiben]

Maybe to avoid any conflict between MBD and drawings partially defined.....or to help transition to MBD.

 

[3DDave]

Y14.41 should cover all MBD questions. Any conflicts should be resolved there.