Does anyone know of a code to add the Bonus Tolerance to the true position value? I.E. if I have the call out TP DIA 0.010 (M) A B(M) C(M) where B and C are diameters each gaining a bonus of .005 in addition to the bonus tolerance of the diametrical feature being .002 so the total bonus would be .012 added to the .010 to give me a total tolerance of .022. Any help would be greatly appreciated.
It does NOT quite work that way. Pcdmis can do this, however, it does NOT leave the hole at 'nominal' but slides the entire part around like on a hard gage to give the final answer, and the deviation of the object hole will be made as close to zero as it can as it 'slides' the part around on the locators.
One could use variable assignments inserted into generic features to simulate a true geometric couterpart. If that is what the OP was addressing with his query then I apologize for my brusk response. However, if the intent is to simulate the "wiggle" that an actual hard gage allows, then said programmer is misappropriating there skills in one of two ways:
1) they should develope there own metrology software or
2) allocate the greater portion of there days to gazing into there own navel
One could use variable assignments inserted into generic features to simulate a true geometric couterpart. If that is what the OP was addressing with his query then I apologize for my brusk response. However, if the intent is to simulate the "wiggle" that an actual hard gage allows, then said programmer is misappropriating there skills in one of two ways: 1) they should develope there own metrology software or 2) allocate the greater portion of there days to gazing into there own navel
All i was saying is if the engineer has done his homework (calculations,stack ups) then the parts should fit together even with bonus tolerance. If they don't then he F'ed up.....I write variables all the time to give the vendor the most tolerance allowed........
All i was saying is if the engineer has done his homework (calculations,stack ups) then the parts should fit together even with bonus tolerance. If they don't then he F'ed up ..... I write variables all the time to give the vendor the most tolerance allowed........
I'm with you so far
At this point here I disagree. When we have 0.010 (M)| A | B(M) | C(M) a quasi best fit must be simulated within the restraints provided by the datums total tolerance. If you can do that then more power to you.
There is another possibility, I am off my rocker in yet another manner. However, I am sticking with what I got so far.
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.
The part is not being held by a fixture so the datums are being probed. It's v4.1 which under the true position dimension it has given me the option to add MMC from up to three datums, which it is calculating the bonus tolerance however it is only applying the bonus from the feature and one of the datums. So what I end up with is a part showing out of tolerance but yet I have bonus tolerance not being used from the second datum feature. I guess what really gets me is if the software isn't going to give me the total bonus tolerance when I select the datums why have it their in the first place.
The part is not being held by a fixture so the datums are being probed. It's v4.1 which under the true position dimension it has given me the option to add MMC from up to three datums, which it is calculating the bonus tolerance however it is only applying the bonus from the feature and one of the datums. So what I end up with is a part showing out of tolerance but yet I have bonus tolerance not being used from the second datum feature. I guess what really gets me is if the software isn't going to give me the total bonus tolerance when I select the datums why have it their in the first place.
It's giving it to you. Try this: Dimension the TP without datums, then dimension it again WITH the datums. You SHOULD see a smaller deviation from nominal for the hole WITH the datums, that is the way Pcdmis does it, the bonus from the datums is used to shift the location of the object hole closer to nominal, as it if were on a solid gage.
