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Xact Measure problem

slesholdofthreep
Has anyone had problems with Xact Measure TP dims? I have various parts with MMC on the DF as well as the Datums. As may be expected the DF and the datums all have different size tolerances. When setting up the dimension I tolerance them correctly, but once created the datum tolerances default to the DF tolerance. I have assigned variables for tolerances with little success. In fact I can type in the correct tolerance right into the dimension in the edit window and.. pfft... it reverts back to the DF tol. I am attempting to use this "improved" method because the hexagoon's say that legacy TP dims don't account for MMC on the datums correctly. WTF!

I am running V4.2mr2, but I have seen this in 4.1 and 4.2mr1.
  • Has anyone had problems with Xact Measure TP dims? I have various parts with MMC on the DF as well as the Datums. As may be expected the DF and the datums all have different size tolerances. When setting up the dimension I tolerance them correctly, but once created the datum tolerances default to the DF tolerance. I have assigned variables for tolerances with little success. In fact I can type in the correct tolerance right into the dimension in the edit window and.. pfft... it reverts back to the DF tol. I am attempting to use this "improved" method because the hexagoon's say that legacy TP dims don't account for MMC on the datums correctly. WTF!

    I am running V4.2mr2, but I have seen this in 4.1 and 4.2mr2.
    I'll take a look in a couple of minutes.
  • Has anyone had problems with Xact Measure TP dims? I have various parts with MMC on the DF as well as the Datums. As may be expected the DF and the datums all have different size tolerances. When setting up the dimension I tolerance them correctly, but once created the datum tolerances default to the DF tolerance. I have assigned variables for tolerances with little success. In fact I can type in the correct tolerance right into the dimension in the edit window and.. pfft... it reverts back to the DF tol. I am attempting to use this "improved" method because the hexagoon's say that legacy TP dims don't account for MMC on the datums correctly. WTF!

    I am running V4.2mr2, but I have seen this in 4.1 and 4.2mr2.

    Gee, when all dimensions were 'legacy', they claimed they WERE right. Hmmmm.
  • I have done this many times and gotten good results.

    I suggest you evaluate your TP first with NO VC on your datums. Make sure you have the correct bonus. I have had instances in the past where PC-DMIS took a ID for an OD and that can cause bad bonusses to happen. Also, if your size is outside the tolerance zone, it will revert to RFS. The bonus will NOT be taken into effect, because the feature is out anyway.

    If that all looks good, add material conditions to your datums. Depending on how the datums are located, this can result in HUGE datum shifts. Basically, when virtual conditions exist on your datums, the TP call changes into a go/no go gauge. The actual numbers don't matter that much any more. The same goes here as I said earlier: if your feature is out of size, PC-DMIS reverts to RFS, including on the datums.

    I have tried this many times now and I think they are doing it right. But this is extremely difficult math and it may be that under certain circumstances, it does not work right. If you become convinced it does not work, call tech support. I have gotten great help on this topic from them.

    Also, when you work with VC's on datums, don't forget to look at simultaneous requirements (see ASME standard). PC-DMIS allows you to account for that too.


    Jan.
  • Thanks for your help everyone. For brevity's sake let me assure you this not PEBKAC (Problem Exists Between Keyboard And Chair). This is straight up buggy shite.
  • Jan, case in point. It will do this even while programming from cad with all the actuals matching the nominals.
  • Thanks for your help everyone. For brevity's sake let me assure you this not PEBKAC (Problem Exists Between Keyboard And Chair). This is straight up buggy shite.

    I like that one! PEBKAC, I'll have to remember that.

    What you COULD try to do is assign the MMC bonus from the datum feature and add it to the TP tolerance of the dimension feature. When you look at it in the edit window, command mode, you will see the math, but in the report window, you will see the answer. At least, that is the way it works in V3.7. 

    DIM D054= TRUE POSITION OF CIRCLE H047  UNITS=MM ,$
GRAPH=OFF  TEXT=OFF  MULT=1.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=ON  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
X    6118.786                                    6119.299      0.513           
Y     -99.606                                     -99.046      0.560           
DF     18.700      0.000      0.500      0.412     18.612     -0.088      0.000 -------#-
TP        MMC      3.000                 0.412                 1.519      0.000 ----#----
END OF DIMENSION D054
            ASSIGN/V1 = D054.DF.BTOL
DIM D055= TRUE POSITION OF CIRCLE H048  UNITS=MM ,$
GRAPH=OFF  TEXT=OFF  MULT=1.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=ON  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
X    6118.786                                    6119.283      0.497           
Y      75.394                                      75.878      0.484           
DF     18.700      0.000      0.500      0.397     18.597     -0.103      0.000 -------#-
TP        MMC  3+V1                 0.397                 1.388      0.000 ---#-----
END OF DIMENSION D055

    and then in the report window it will look like this: 
    DIM D054= TRUE POSITION OF CIRCLE H047  UNITS=MM
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
X    6118.786                                    6119.299      0.513           
Y     -99.606                                     -99.046      0.560           
DF     18.700      0.000      0.500      0.412     18.612     -0.088      0.000 -------#-
TP        MMC      3.000                 0.412                 1.519      0.000 ----#----
 
DIM D055= TRUE POSITION OF CIRCLE H048  UNITS=MM
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
X    6118.786                                    6119.283      0.497           
Y      75.394                                      75.878      0.484           
DF     18.700      0.000      0.500      0.397     18.597     -0.103      0.000 -------#-
TP        MMC      3.412                 0.397                 1.388      0.000 ---#-----


    Does that help?
  • Another point, If you have multiple holes to report from the same TP callout, do not do them al in the same FCF for TP!!

    If you do and you want stats from all the holes, goodluck. I don't know which single TP it sends to stats (worst, best, average?), but all you get is 1 stat for a FCF that has more than 1 hole reported in it.

    Workaround? Just dimension each one individually. I like it better that way anyways.
  • Matt- thats a good one when you have a VC on the DF only. Unfortunately, I have VCs on the datums as well which requires a qausi BF on the datums limited to there individual tolerances. If I had a coding solution for that I would be a much better programmer than I am.

    James- thanks for the tip. On a side note, do you think it reports the deviation for the set when dimensioning a group?
  • Matt- thats a good one when you have a VC on the DF only. Unfortunately, I have VCs on the datums as well which requires a qausi BF on the datums limited to there individual tolerances. If I had a coding solution for that I would be a much better programmer than I am.

    James- thanks for the tip. On a side note, do you think it reports the deviation for the set when dimensioning a group?

    Well, is it possible for you to use the datums as you need for the TP, but set it to RFS for the datums, and then still use the method I showed for getting the bonus from the diameter? I mean, if you use "abc" datums for the TP, it will align to those features, making them 'perfect', then giving the TP of the hole you are dimensioning. So, you put in a TP dimension for the datum hole, just to get the size bonus (set it to report to NONE instead of REPORT/STATS/BOTH) to add to the TP tolerance for the hole you are dimensioning.
  • Another point, If you have multiple holes to report from the same TP callout, do not do them al in the same FCF for TP!!

    If you do and you want stats from all the holes, goodluck. I don't know which single TP it sends to stats (worst, best, average?), but all you get is 1 stat for a FCF that has more than 1 hole reported in it.

    Workaround? Just dimension each one individually. I like it better that way anyways.

    Also, when you work with VC's on datums, don't forget to look at simultaneous requirements (see ASME standard). PC-DMIS allows you to account for that too.

    James, this is only a problem when you need stats for multiple holes right? I ask because doesn't this method solve for simultaneous requirement Jan mentioned?

    Jan, in light of James' statement could one use PCDMIS silmultaneous evaluation function?
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