I'm sure I've simply missed the exact answer I am hunting for. I'll make the question clear, and please feel free to point it out. Currently have a copy of
ASME Y14.5M-1994 but doubt any better clarification in the 2009 standard.
datum c bore has a positional tolerance of .007mmc to datum A, and it's diameter tolerance is +.006/-0. This gives the feature a maximum positional tolerance of .013 with the largest passing bore.
datum b bore has a positional tolerance of .060mmc to datum A, and it's diameter tolerance is +.006/-0. This gives the feature a maximum positional tolerance of .066 with the largest passing bore.
Now a reference frame for the hole(size +.006-.000) in question is .030MMC to A, [email protected], [email protected]
Assuming the hole is at the minimum diameter. The hole gets a positional tolerance of .030 from the first box of the feature frame. It should also be getting 1/2 the bonus from the -B- and -C- datums.
Down to the actual question:
Does that mean it gets 1/2 of the .066 from -B-? or only half of the .006 for the actual diameter. I have not seen a single example with a table showing anything where the datum has it's bonus. Every single example the datum has a 0 tolerance.
Without complicating it to discuss multiple holes, how would the single hole be treated. And where, exactly, is that stated from the specification. For example a table that show the datum shift bonus is in figure 5-48 on page 144. This is specific to positional tolerancing for coaxiality, but shows the concept i'm after.
As always I appreciate the help. Hope everyone is having a good holiday season.