Mmc

Can’t believe most inspectors and especially engineers don’t know this!

On a hole diameter MMC = Actual measured hole size minus the smallest allowable size which is the MMC condition… max material.

So for TP .5 on a 10.0 +/- .5 hole that measures 10.1
You get .6 Bonus (actual size 10.1 minus the smallest size 9.5 = .6) this .6 extra tolerance is then added to the given .5 TP tolerance for a grand total of 1.1 tolerance.

For a solid pin or outside cylinder it’s outside diameter, same concept. Largest allowable size minus the actual = Bonus Tolerance.

BONUS TOLERANCE =
DIFFERENCE BETWEEN MMC SIZE AND ACTUAL SIZE! ADDED TO GIVEN TP TOLERANCE IN THE FEATURE CONTROL FRAME.

DAN_M over 1 year ago

Here is a good one for y'all:

Print Rev 1: Ø.130±.003 T.P. w/in .002|A(LMC)|B(LMC)| (-A- is an OD...Ø.130 is an OD...-B- is an OD)

Us: Hey customer, we're having problems with this feature, can you open the tolerance for us? (The fact that this GDT is really useless is so over their heads that we don't even bother bringing it up...)

Customer: Hold my beer...

Print Rev 2: Ø0.130±.002 T.P. w/in .003|A(MMC)|B(MMC)|

Note:
THEY TOLD US to intentionally hold -A- and -B- towards low limit so we can try to get more bonus tolerance elsewhere around the part.....they give us a healthy ±.0010 on diameter size
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KronkGitBasher over 1 year ago

I have a coworker, that has been an inspector for 30+ years, that says MMC on datums and datum shift do not exist and that I just made them up. He even went on to say that, if PC DMIS allows it, then it is unreliable and cannot be used. It is not as accurate as his manual machine running of GEO PAK.
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bfire85 over 1 year ago

I have a coworker, that has been an inspector for 30+ years, that says MMC on datums and datum shift do not exist and that I just made them up. He even went on to say that, if PC DMIS allows it, then it is unreliable and cannot be used. It is not as accurate as his manual machine running of GEO PAK.

Have you asked him to build you a functional gage with proper tolerance stack-ups?
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cheesiechanman over 1 year ago

I have a coworker, that has been an inspector for 30+ years, that says MMC on datums and datum shift do not exist and that I just made them up. He even went on to say that, if PC DMIS allows it, then it is unreliable and cannot be used. It is not as accurate as his manual machine running of GEO PAK.

Hit him with the "I would agree with you... but then we would both be wrong."
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KronkGitBasher over 1 year ago in reply to bfire85

"WE" don't stack tolerances... according to him. It sometimes makes my head hurt.
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KronkGitBasher over 1 year ago in reply to cheesiechanman

I have said, a few times, that I will notify the world not to use PC DMIS on his authority.... and wait for the world to laugh at him.
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Neil Challinor over 1 year ago in reply to cheesiechanman

I assume he's never read either ASME Y14.5 or ISO 1101?
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KronkGitBasher over 1 year ago in reply to cheesiechanman

2+2=4 hasn't changed in his 30 years of inspection, why should any of the rest of it. I have literally watched him tell people that International standards wrong.
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DAN_M over 1 year ago

KronkGitBasher My buddy was buying a car last week. He got into an argument with the Finance Manager (who had an MBA on the wall). They tried to pull the ole' switcheroo with the interest rate at the last minute..guy got p!ssed and during the incident yelled "he doesn't believe in math or calculators!". Must be related to your co-worker
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KronkGitBasher over 1 year ago

KronkGitBasher My buddy was buying a car last week. He got into an argument with the Finance Manager (who had an MBA on the wall). They tried to pull the ole' switcheroo with the interest rate at the last minute..guy got p!ssed and during the incident yelled "he doesn't believe in math or calculators!". Must be related to your co-worker

My coworker IS the calculator. It wouldn't surprise me if he wrote a letter to Texas Instruments telling them that their calculators are wrong.
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