I hope this is as simple as I think it is. I have a part the calls out the true position of a 5/16-18 ID threaded hole with MMC. I think that the MMC should come off of the minor diameter. Onr of the owners and the QA manager think it should come off of the pitch diameter. Other than the fact we don't have a good way to measure the pitch diameter in house I think they are wrong. What are the prevailing winds on minor or pitch for MMC on a ID threaded hole?
I once found the tolerances for threads, to apply MMC is almost a moot point. Look at it this way, if they were that concerned about location, they probably wouldn't be using a screw or bolt to locate it. It just goes back to some Engineers not having a frickin clue. I ignore MMC on a thread period. If you take a screw and thread it in, can it wiggle to the left or right ? NO, its self centering. I can't believe we even need to have these discussions because of the lack of understanding by the people making the drawings, it disgusts me.
I once found the tolerances for threads, to apply MMC is almost a moot point. Look at it this way, if they were that concerned about location, they probably wouldn't be using a screw or bolt to locate it. It just goes back to some Engineers not having a frickin clue. I ignore MMC on a thread period. If you take a screw and thread it in, can it wiggle to the left or right ? NO, its self centering. I can't believe we even need to have these discussions because of the lack of understanding by the people making the drawings, it disgusts me.
