What is total size tolerance for features controlled by this callout?
If it is greater than .020, the requirement defined in the FRTZF may mean nothing for actual sizes allowing bonus tolerance to be greater than .020.
I would not however say it is illegal - at least in my opinion it does not violate any rule of composite positional tolerancing.
If I am not too late - I used term "legal but useless" on this forum before.
Exactly for the reason that FRTZF value may become larger, I wouldn't recommend anyone to use it. But I couldn't find anything explicitly forbidding the technique.
Your tolerance box can be interpreted as per ASME Y14.5M-1994. The top tolerance box even makes sense to me. You are specifying the accuracy with which a hole pattern is located. This does not require MMC. Your second box ensures that screws pass through the holes. MMC now is a useful concept.
When you say "legal", I have visions of Captain GD&T smashing his way into your office and hurling a mouse pad at you.
Thank you gentlemen
So, the conclusion is:
It is ALLOWED or WITHIN THE SCOPE of the standard (legal)
Pmarc,
Quote: "What is total size tolerance for features controlled by this callout?
If it is greater than .020, the requirement defined in the FRTZF may mean nothing for actual sizes allowing bonus tolerance to be greater than .020."
The size is within ±.005, so, total size tolerance is .010 for features controlled by the callout.