Unilateral Tolerancing

[avc8130]

In 14.5-1994 is .500+005 a valid callout?
Thanks,
Anthony

 

[ewh]

+.500/-.000 is.

Believe it if you need it or leave it if you dare. - [small]Robert Hunter[/small]

 

[avc8130]

Ok, so the callout would have to be .500 +.005/-.000?

 

[KENAT]

Yep, ewh got it. The callout in the OP is incorrect.

Per 2.3.2 Inch Tolerances (a)"Where unilateral tolerancing is used and either the plus or minus value is nil, its dimension shall be expressed with the same number of decimal places and the appropriate plus or minus sign.

KENAT, probably the least qualified checker you'll ever meet...

 

[CheckerRon]

To echo ewh and Kenat, there is no "plus only" tolerance callout in Y14.5. Anyone who reads your drawing will ask the question, "if the + tolerance is .005, what is the minus?"

At the large rocket company I work at now, they are big on "target dimensions" which in their DRM means nominal or mean dimension that you set your process to achieve. Therefore they do not allow unilateral dimensioning on drawings. Every dimension must be nominal (target) with either an equilateral ± tolerance or an unequal + something, - something, but not zero. That also means converting recommended unilateral tolerances such as O-Ring groove diameters. It also applies to both Metric or imperial, whichever were working in.