pcm for mmc bonus

[[Th...]]

I want to do a simple if / then PCM.
if getactual("Cyl A").diameter is < .500 then 0.010 else 0.010 + getactual("Cyl A").diameter -0.495 endif

Dia A required size is 0.500 ± 0.005

I have bore (Dia A) and counterbore (Dia B).
True Position is called out on Dia B as:
[ Tru Pos | ø.010 | A(M) ]

MMC on the datum instead of the feature. Calypso is not calculating MMC on the datum which is why I want to add this PCM.
Can not get the syntax right.
Appreciate any help.

[[Cl...]]

getActual("Your feature here").diameter - 0.9125 + 0.001 (ID)
getActual("Datum -A-").diameter - 0.9350 - 0.0005 (OD) ?
getActual("Cylinder -L-").diameter - 0.9325 ± 0.00015 ?

[[Ri...]]

You do not get extra tolerance if the modifier is on your Datum. MMC/LMC is if the modifier is on the feature. MMB/LMB is if the modifier is on the Datum.

MMB/LMB is called Datum Shift. Where now you create a virtual envelope where the Datum can move within - thus changing the basic dimension.

More than likely you will see that it will remove error in the result.

There isn't a formula that you can input to use it.

[[An...]]

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Indeed,there is a tolerance bonus:
If all tolerated bores deviate in the same direction.
(Drill head)

[[Cl...]]

The "Datum Shift" method is only how Calypso applies it, right? If you were doing
a manual surface plate layout then it would be just plain old bonus tolerance, correct?

[[Ja...]]

Y14.5-2009 7.3.6.2.2 (a) 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.

Clarke, the idea behind using a manual surface plate layout is that the datum displacement is automatically accounted for (as usable slop in the gage) if and only if the datums are simulated at their proper material boundary size found by considering datum feature limits of size and any applicable geometric tolerance to datums of higher precedence.

In very basic situations, like an O.D. cylinder positioned to a concentric I.D. datum at MMB, the datum displacement can work as traditional bonus tolerance. In the large majority of callouts, this is not the case. I find it best to strongly differentiate between the two.

[[Th...]]

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thanks Richard. you're correct. I dug into the specs more and analyzed what Calypso is doing and Calypso is working properly. thanks again for pointing me in the right direction.

[[Wi...]]

Not bonus like MMC only shift.... you get no extra