Maximum Material Boundary vs Maximum Material Condition

[[Ro...]]

First off, this is NOT a bolt circle pattern, so i don't think that video with that dude applies here.
True position situation.

Think of a golf ball cut in half, and a hole drilled into the core. the flat plane is Dat A, the hole is Dat B and the outer sphere is being measured to A & B.

We get no material bonus on the outer sphere but we do get MMC on the drilled hole.

Customer is questioning if we get any additional bonus tolerance for the TP.

Of course calypso will not allow me to select MMC for a secondary datum.

I suck at standards, but the print says to interpret to asme Y14.5

So do i get bonus or what?
easy answers only please.

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[[Ja...]]

The modifier is on your datum, hence you don't get "bonus". Instead, you are granted datum mobility. Calypso cannot calculate this in this case. Essentially, as your bore deviates from it's actual mating envelope at MMC, your O.D. sphere is allowed to functionally shift around your datum to minimize position error.

Think of sticking your part on a pin at your hole MMC size. If your bore is at MMC, it'd be a tight fit and your sphere would be where it is in space. Now if you open the bore up, you can shift the part around the pin, effectively "moving the sphere" and coming into tolerance (relative to the pin, really).

I would run it without MMB, not that you can't unless you switch it over to PCDMIS.

[[Ro...]]

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That description sounds exactly like MMC bonus to me.
But i suck at standards, and i have the feeling i'm on the losing side of this argument, so ill go with no bonus.

[[Me...]]

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Don't think of it as a Bonus. Think of it as a sort of combination of translational shifts, you can't add to the True Position tolerance with MMB, so there is zero Bonus tolerance.

[[Ja...]]

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ASME Y14.5M-2009 7.3.6.2.2 :
...The amount of the datum feature’s departure from MMB does not provide additional positional tolerance for each of the considered features in relation to each other within the pattern....
...If a functional gage is used to check the part, the relative movement between datum axis B and the axis of the datum feature is automatically accommodated....

[[Me...]]

Calypso can use mmc of datums. See this article to evaluate using best fit.

http://cmmquarterly.mbccmm.com/index.ph ... pso-part-3

[[Ja...]]

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Does this work when your "Bore pattern" consists of one feature? Also, OP has Profile, not Position.