I am not trying to simulate a hard gage, rather simply trying to use all of the available tolerance the print allows.
OK, first, lets look at HOW you are holding this part. Now, I know some will not agree with me, BUT, if you are holding this part on a holding/checking fixture that uses taper stab pins, forget about the datum bonus, just use the bonus for the hole as the fixture has 'taken away' the slop the MMC would give you on the locator as opposed to the fixture using a straight pin.
IF you are looking to get all the bonus you can, simply use the PCDMIS TP in V3.7+ WITH datum call out. I may not agree with the way it does it (and I don't) but it will give you all the bonus tolerance you are allowed for the hole & the datums. You really have no choice since the calcualtions get way beyond anythign you want to deal with. The 4-Way (round) locator and the 2-Way (slot perhaps) locator will give a different effective bonus for each hole you check on the part, based upon distance from the datums, angle, and so forth. You may NOT see the BONUS from the datums show in the TP TOLERANCE, but you never will. It will, however, do what is called a datum shift, as much as it can, so that the actual locators would be pressing against 'perfect' MMC pins, then give the deviation of the subject hole you are dimensioning.
I am not trying to simulate a hard gage, rather simply trying to use all of the available tolerance the print allows.
OK, first, lets look at HOW you are holding this part. Now, I know some will not agree with me, BUT, if you are holding this part on a holding/checking fixture that uses taper stab pins, forget about the datum bonus, just use the bonus for the hole as the fixture has 'taken away' the slop the MMC would give you on the locator as opposed to the fixture using a straight pin.
IF you are looking to get all the bonus you can, simply use the PCDMIS TP in V3.7+ WITH datum call out. I may not agree with the way it does it (and I don't) but it will give you all the bonus tolerance you are allowed for the hole & the datums. You really have no choice since the calcualtions get way beyond anythign you want to deal with. The 4-Way (round) locator and the 2-Way (slot perhaps) locator will give a different effective bonus for each hole you check on the part, based upon distance from the datums, angle, and so forth. You may NOT see the BONUS from the datums show in the TP TOLERANCE, but you never will. It will, however, do what is called a datum shift, as much as it can, so that the actual locators would be pressing against 'perfect' MMC pins, then give the deviation of the subject hole you are dimensioning.
