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MMC by hand

Good morning,
We've been asked to report the position and parallelism of a keyway to a bore. It's a simple bore, with a one straight keyway in it. We have also been asked to use the MMC bonus in the calculations. The keyway is shallow enough that we can't get two good planes from the sides, or we would use a width feature. We've tried to make a width feature using two lines constructed from points taken on the sides of the keyway. We either don't understand that process well enough to make it work, or it just doesn't. Anyway, we've decided to do this in legacy, using an alignment. One advantage of this is that we can clearly demonstrate our process to disbelieving minds. We have somewhat figured out how to use assign to do some simple arithmetic. We can assign the value of a letter or something to be the measured value of the bore, minus the smallest (maximum material condition), allowable diameter of the bore. We can subtract that bonus from a reported position or parallelism, and report the result of that using a generic feature. What we haven't been able to figure out is how to keep our report from showing a minus number if the position is really good, and the bonus is large. (we know that pcdmis reports the actual position, but doesn't turn it red if the bonus is large enough) We're sure there is a way. We've looked at the "if then" stuff for pcdmis on the internet, and we're going to try and fumble our way through that on Monday morning.

Can someone possibly direct us to some good "help" information, or maybe provide a simple example of how to correctly do what we are trying to do? Being able to do this kind of "if then" arithmetic is something we could use a lot.

Thanks for your help.
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  • I would also slap one of these in there ...

    ASSIGN/V1=IF(OR(V1<0,SLOT_1.DF.MEAS>2.004),0,V1)


    It's always been my understanding that if a feature is OOT on size, big or small, it contributes no bonus to your position call-out.
  • A feature with +/- .004 has a max potential feature bonus of .008 that can be applied. If the feature is produced and the calculation would generate a .009 bonus, then that is illegal per a callout with (M)/(L) represented and needs to be limited to the .008 while if your feature was produced and the calculation would result in -0.001, it would default to 0. So you still can gain a bonus with a non-conforming size. We and our customers tend to align to the same idea whenever we have come across an issue like this.
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  • A feature with +/- .004 has a max potential feature bonus of .008 that can be applied. If the feature is produced and the calculation would generate a .009 bonus, then that is illegal per a callout with (M)/(L) represented and needs to be limited to the .008 while if your feature was produced and the calculation would result in -0.001, it would default to 0. So you still can gain a bonus with a non-conforming size. We and our customers tend to align to the same idea whenever we have come across an issue like this.
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