Composite position, threaded hole pattern

I have a cylindrical part with a set of holes drilled 90 deg apart (3 o'clock, 6 o'clock, 9 o'clock and noon) around the circumference. Total of 8 holes- 4 at one level, 4 at another. The callout is very common to this type part, a PLTZF callout of .038" RFS to A|B, then a FRTZF callout of .018" RFS to A.

My question, if I have done this properly in my PC-DMIS program, is there any way that all 8 holes could pass for the upper PLTZF callout, and simultaneously all 8 holes fail the FRTZF callout? I can't see how they could, but when I executed a program recently that I've used on many of these same parts, this is exactly what the results show.

On a side-note, the drawing doesn't restrain all 6 degrees of freedom, so I chose a feature on the part that made sense to me to use to close that gap.

Thanks in advance

Parents

DJAMS over 12 years ago

(v3.7MR3 doesn't seem to have the tools you mentioned, at least not in the Best Fit Alignment dialog box). So if Im understanding this correctly, I should make sure I've got my cursor inside the 2D-best-fit (the one I normally do), then create a new alignment and only change the Z origin with that alignment?

Like this?
set origin =ALIGNMENT/START,RECALL:2dBF_8Holes, LIST= YES
ALIGNMENT/TRANS,ZAXIS,MPLN1
ALIGNMENT/END

Yes. I'd like to point out that constructing the plane as I suggested is just a way of "averaging" the deviations of the features. It can still reject good parts (as can any of the best fit alignments), but it will never accept bad parts.

I think that "Specified Constraints" in best fit alignments showed up sometime during the 2010 release cycle.

Doing it that way, I got the following result...

DIM LOC19= TRUE POSITION OF CIRCLE C1  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8544    -0.0009           
PR     1.6336                                      1.6324    -0.0012           
PA   -89.9870                                    -90.0082    -0.0212           
DF     0.1042     0.0000     0.0000                0.1084     0.0042     0.0042 -------->
TP        RFS     0.0180                0.0000                0.0033     0.0000 -#-------
END OF DIMENSION LOC19
DIM LOC20= TRUE POSITION OF CIRCLE C2  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8543     0.0009           
DF     0.1042     0.0000     0.0000                0.1072     0.0030     0.0030 -------->
TP        RFS     0.0180                0.0000                0.0017     0.0000 #--------
PR     1.6336                                      1.6314    -0.0022           
PA   -89.9878                                    -89.8944     0.0934           
END OF DIMENSION LOC20
DIM LOC21= TRUE POSITION OF CIRCLE C3  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8503     0.0032           
DF     0.1042     0.0000     0.0000                0.1058     0.0016     0.0016 -------->
TP        RFS     0.0180                0.0000                0.0064     0.0000 ---#-----
PR     1.6337                                      1.6364     0.0028           
PA  -179.9876                                    179.9900    -0.0224           
END OF DIMENSION LOC21
DIM LOC22= TRUE POSITION OF CIRCLE C4  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8527    -0.0008           
DF     0.1042     0.0000     0.0000                0.1064     0.0022     0.0022 -------->
TP        RFS     0.0180                0.0000                0.0015     0.0000 #--------
PR     1.6327                                      1.6299    -0.0028           
PA   179.9879                                   -179.9293     0.0828           
END OF DIMENSION LOC22
DIM LOC23= TRUE POSITION OF CIRCLE C5  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8522     0.0013           
DF     0.1042     0.0000     0.0000                0.1072     0.0030     0.0030 -------->
TP        RFS     0.0180                0.0000                0.0026     0.0000 -#-------
PR     1.6334                                      1.6335     0.0001           
PA    90.0118                                     90.0412     0.0294           
END OF DIMENSION LOC23
DIM LOC24= TRUE POSITION OF CIRCLE C6  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8542     0.0007           
DF     0.1042     0.0000     0.0000                0.1067     0.0025     0.0025 -------->
TP        RFS     0.0180                0.0000                0.0014     0.0000 #--------
PR     1.6336                                      1.6339     0.0004           
PA    90.0120                                     89.9267    -0.0854           
END OF DIMENSION LOC24
DIM LOC25= TRUE POSITION OF CIRCLE C7  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8581    -0.0047           
DF     0.1042     0.0000     0.0000                0.1151     0.0109     0.0109 -------->
TP        RFS     0.0180                0.0000                0.0093     0.0000 ----#----
PR     1.6336                                      1.6293    -0.0042           
PA     0.0120                                     -0.0130    -0.0250           
END OF DIMENSION LOC25
DIM LOC26= TRUE POSITION OF CIRCLE C8  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8538     0.0003           
DF     0.1042     0.0000     0.0000                0.1092     0.0050     0.0050 -------->
TP        RFS     0.0180                0.0000                0.0005     0.0000 #--------
PR     1.6333                                      1.6338     0.0005           
PA     0.0121                                     -0.0392    -0.0513           
END OF DIMENSION LOC26

Everything reports OK. But still not sure if this is what you had in mind.

This reporting is a problem. The reported position results are not correct (except for maybe the 1st dimension). Notice that in all the dimensions except the 1st one, the TP deviation is simply 2X the Z deviation(+/- rounding error) - the X or Y deviation is not being included in the position result. I believe this is because in the 1st dimension,PR/PA are reported before TP and in all the others PR/PA is reported after TP. If this were my program, I wouldn't even report PR/PA. For the holes at 12 and 6 o'clock, report X,Z,TP. For the holes at 3 and 6 o'clock, report Y,Z,TP. The other thing I would recommend is DEV PERPEN CENTERLINE=ON. It shouldn't make any difference in this case, but it's a good habit to leave it on for the situations where it does matter.

Reply

DJAMS over 12 years ago

(v3.7MR3 doesn't seem to have the tools you mentioned, at least not in the Best Fit Alignment dialog box). So if Im understanding this correctly, I should make sure I've got my cursor inside the 2D-best-fit (the one I normally do), then create a new alignment and only change the Z origin with that alignment?

Like this?
set origin =ALIGNMENT/START,RECALL:2dBF_8Holes, LIST= YES
ALIGNMENT/TRANS,ZAXIS,MPLN1
ALIGNMENT/END

Doing it that way, I got the following result...

DIM LOC19= TRUE POSITION OF CIRCLE C1  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8544    -0.0009           
PR     1.6336                                      1.6324    -0.0012           
PA   -89.9870                                    -90.0082    -0.0212           
DF     0.1042     0.0000     0.0000                0.1084     0.0042     0.0042 -------->
TP        RFS     0.0180                0.0000                0.0033     0.0000 -#-------
END OF DIMENSION LOC19
DIM LOC20= TRUE POSITION OF CIRCLE C2  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8543     0.0009           
DF     0.1042     0.0000     0.0000                0.1072     0.0030     0.0030 -------->
TP        RFS     0.0180                0.0000                0.0017     0.0000 #--------
PR     1.6336                                      1.6314    -0.0022           
PA   -89.9878                                    -89.8944     0.0934           
END OF DIMENSION LOC20
DIM LOC21= TRUE POSITION OF CIRCLE C3  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8503     0.0032           
DF     0.1042     0.0000     0.0000                0.1058     0.0016     0.0016 -------->
TP        RFS     0.0180                0.0000                0.0064     0.0000 ---#-----
PR     1.6337                                      1.6364     0.0028           
PA  -179.9876                                    179.9900    -0.0224           
END OF DIMENSION LOC21
DIM LOC22= TRUE POSITION OF CIRCLE C4  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8527    -0.0008           
DF     0.1042     0.0000     0.0000                0.1064     0.0022     0.0022 -------->
TP        RFS     0.0180                0.0000                0.0015     0.0000 #--------
PR     1.6327                                      1.6299    -0.0028           
PA   179.9879                                   -179.9293     0.0828           
END OF DIMENSION LOC22
DIM LOC23= TRUE POSITION OF CIRCLE C5  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8522     0.0013           
DF     0.1042     0.0000     0.0000                0.1072     0.0030     0.0030 -------->
TP        RFS     0.0180                0.0000                0.0026     0.0000 -#-------
PR     1.6334                                      1.6335     0.0001           
PA    90.0118                                     90.0412     0.0294           
END OF DIMENSION LOC23
DIM LOC24= TRUE POSITION OF CIRCLE C6  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8542     0.0007           
DF     0.1042     0.0000     0.0000                0.1067     0.0025     0.0025 -------->
TP        RFS     0.0180                0.0000                0.0014     0.0000 #--------
PR     1.6336                                      1.6339     0.0004           
PA    90.0120                                     89.9267    -0.0854           
END OF DIMENSION LOC24
DIM LOC25= TRUE POSITION OF CIRCLE C7  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z     -1.8535                                     -1.8581    -0.0047           
DF     0.1042     0.0000     0.0000                0.1151     0.0109     0.0109 -------->
TP        RFS     0.0180                0.0000                0.0093     0.0000 ----#----
PR     1.6336                                      1.6293    -0.0042           
PA     0.0120                                     -0.0130    -0.0250           
END OF DIMENSION LOC25
DIM LOC26= TRUE POSITION OF CIRCLE C8  UNITS=IN ,$
GRAPH=OFF  TEXT=OFF  MULT=10.00  OUTPUT=BOTH  DEV PERPEN CENTERLINE=OFF  DISPLAY=DIAMETER
AX   NOMINAL     +TOL       -TOL       BONUS      MEAS        DEV      OUTTOL   
Z      1.8535                                      1.8538     0.0003           
DF     0.1042     0.0000     0.0000                0.1092     0.0050     0.0050 -------->
TP        RFS     0.0180                0.0000                0.0005     0.0000 #--------
PR     1.6333                                      1.6338     0.0005           
PA     0.0121                                     -0.0392    -0.0513           
END OF DIMENSION LOC26

Everything reports OK. But still not sure if this is what you had in mind.

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