How would one calculate pitch diameter for external threads on a CMM and verify that the results are correct. I need to check some pretty large acme threads im not too sure about the nominal dimensions.
Measuring pitch diameter is still on top of my list. I've gotten some help form Hexagon but they have only been able to do this offline. To make this worse, the threads on my cad model do not match the physical part. That is how Hex was able to accomplish this. The physical part has consistent start and finish so my program is repeatable part to part without any unexpected bumps. I just have to take manual hits, adjust the nominals and test in DCC.
TIP/T2A0B0, SHANKIJK=-1, 0.0002, 0, ANGLE=0
PNT54 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-1.9129,6.0287,-3.852>,<-0.2502852,-0.9677811,0.0275136>
PNT55 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.0239,6.0574,-3.852>,<-0.2502953,-0.9678202,0.0260057>
LIN1 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<-1.9129,6.0287,-3.852>,<-0.9681477,0.2503799,-0.0000019>
ACTL/<-1.9129,6.0287,-3.852>,<-0.9681477,0.2503799,-0.0000019>
CONSTR/LINE,BF,3D,PNT54,PNT55,,
PNT58 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-1.9079,5.8896,-3.852>,<0.2502847,-0.9677792,0.0275856>
PNT59 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.0018,5.8653,-3.852>,<0.2502934,-0.967813,0.0262925>
LIN2 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<-1.9079,5.8896,-3.852>,<-0.9681476,-0.2503801,-0.0000042>
ACTL/<-1.9079,5.8896,-3.852>,<-0.9681476,-0.2503801,-0.0000042>
CONSTR/LINE,BF,3D,PNT58,PNT59,,
PNT60 =FEAT/POINT,CARTESIAN,NO
THEO/<-1.6415,5.9585,-3.852>,<-0.9681477,0.2503799,-0.0000019>
PNT62 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.0208,6.027,-3.852>,<0.2502951,0.9678192,0.0260455>
PNT63 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<1.8984,6.1915,-3.852>,<-0.2502838,0.9677755,0.0277236>
PNT64 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<1.969,6.2098,-3.852>,<-0.2502906,0.9678017,0.0267303>
LIN3 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<1.9126,6.055,-3.852>,<0.9681476,-0.2503801,0.0000036>
ACTL/<1.9126,6.055,-3.852>,<0.9681476,-0.2503801,0.0000036>
CONSTR/LINE,BF,3D,PNT61,PNT62,,
LIN4 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<1.8984,6.1915,-3.852>,<0.9681478,0.2503795,0.0000195>
ACTL/<1.8984,6.1915,-3.852>,<0.9681478,0.2503795,0.0000195>
CONSTR/LINE,BF,3D,PNT63,PNT64,,
PNT65 =FEAT/POINT,CARTESIAN,NO
THEO/<1.6415,6.1251,-3.852>,<0.9681476,-0.2503801,0.0000036>
ACTL/<1.6415,6.1251,-3.852>,<0.9681476,-0.2503801,0.0000036>
CONSTR/POINT,INT,LIN3,LIN4
(***Moderator Edit: I assume there's the correct workplane already in place***)
DIM ANGL1= 2D ANGLE FROM LINE LIN3 TO LINE LIN4 ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 29.0000 0.5000 0.5000 29.0000 0.0000 0.0000 ----#----
ASSIGN/V1=ANGL1.MEAS/2
ASSIGN/V2=DEG2RAD(V1)
ASSIGN/V3=TAN(V2)
ASSIGN/V4=0.17215/2
ASSIGN/V5=V4/V3
ASSIGN/V6=COS(V2)*V5
DIM ANGL2= 2D ANGLE FROM LINE LIN1 TO LINE LIN2 ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 29.0000 0.5000 0.5000 29.0000 0.0000 0.0000 ----#----
ASSIGN/V7=ANGL2.MEAS/2
ASSIGN/V8=DEG2RAD(V7)
ASSIGN/V9=TAN(V8)
ASSIGN/V10=V4/V9
ASSIGN/V11=COS(V8)*V10
DIM DIST1= 2D DISTANCE FROM POINT PNT60 TO POINT PNT65 PAR TO XAXIS,NO_RADIUS UNITS=IN,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
M 3.2831 0.0050 0.0050 3.2831 0.0000 0.0000 ----#----
ASSIGN/V12=DIST1.MEAS+V6+V11
COMMENT/REPT,
"Pitch Diameter= " +V12
Measuring pitch diameter is still on top of my list. I've gotten some help form Hexagon but they have only been able to do this offline. To make this worse, the threads on my cad model do not match the physical part. That is how Hex was able to accomplish this. The physical part has consistent start and finish so my program is repeatable part to part without any unexpected bumps. I just have to take manual hits, adjust the nominals and test in DCC.
TIP/T2A0B0, SHANKIJK=-1, 0.0002, 0, ANGLE=0
PNT54 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-1.9129,6.0287,-3.852>,<-0.2502852,-0.9677811,0.0275136>
PNT55 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.0239,6.0574,-3.852>,<-0.2502953,-0.9678202,0.0260057>
LIN1 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<-1.9129,6.0287,-3.852>,<-0.9681477,0.2503799,-0.0000019>
ACTL/<-1.9129,6.0287,-3.852>,<-0.9681477,0.2503799,-0.0000019>
CONSTR/LINE,BF,3D,PNT54,PNT55,,
PNT58 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-1.9079,5.8896,-3.852>,<0.2502847,-0.9677792,0.0275856>
PNT59 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.0018,5.8653,-3.852>,<0.2502934,-0.967813,0.0262925>
LIN2 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<-1.9079,5.8896,-3.852>,<-0.9681476,-0.2503801,-0.0000042>
ACTL/<-1.9079,5.8896,-3.852>,<-0.9681476,-0.2503801,-0.0000042>
CONSTR/LINE,BF,3D,PNT58,PNT59,,
PNT60 =FEAT/POINT,CARTESIAN,NO
THEO/<-1.6415,5.9585,-3.852>,<-0.9681477,0.2503799,-0.0000019>
PNT62 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.0208,6.027,-3.852>,<0.2502951,0.9678192,0.0260455>
PNT63 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<1.8984,6.1915,-3.852>,<-0.2502838,0.9677755,0.0277236>
PNT64 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<1.969,6.2098,-3.852>,<-0.2502906,0.9678017,0.0267303>
LIN3 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<1.9126,6.055,-3.852>,<0.9681476,-0.2503801,0.0000036>
ACTL/<1.9126,6.055,-3.852>,<0.9681476,-0.2503801,0.0000036>
CONSTR/LINE,BF,3D,PNT61,PNT62,,
LIN4 =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<1.8984,6.1915,-3.852>,<0.9681478,0.2503795,0.0000195>
ACTL/<1.8984,6.1915,-3.852>,<0.9681478,0.2503795,0.0000195>
CONSTR/LINE,BF,3D,PNT63,PNT64,,
PNT65 =FEAT/POINT,CARTESIAN,NO
THEO/<1.6415,6.1251,-3.852>,<0.9681476,-0.2503801,0.0000036>
ACTL/<1.6415,6.1251,-3.852>,<0.9681476,-0.2503801,0.0000036>
CONSTR/POINT,INT,LIN3,LIN4
(***Moderator Edit: I assume there's the correct workplane already in place***)
DIM ANGL1= 2D ANGLE FROM LINE LIN3 TO LINE LIN4 ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 29.0000 0.5000 0.5000 29.0000 0.0000 0.0000 ----#----
ASSIGN/V1=ANGL1.MEAS/2
ASSIGN/V2=DEG2RAD(V1)
ASSIGN/V3=TAN(V2)
ASSIGN/V4=0.17215/2
ASSIGN/V5=V4/V3
ASSIGN/V6=COS(V2)*V5
DIM ANGL2= 2D ANGLE FROM LINE LIN1 TO LINE LIN2 ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
A 29.0000 0.5000 0.5000 29.0000 0.0000 0.0000 ----#----
ASSIGN/V7=ANGL2.MEAS/2
ASSIGN/V8=DEG2RAD(V7)
ASSIGN/V9=TAN(V8)
ASSIGN/V10=V4/V9
ASSIGN/V11=COS(V8)*V10
DIM DIST1= 2D DISTANCE FROM POINT PNT60 TO POINT PNT65 PAR TO XAXIS,NO_RADIUS UNITS=IN,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE
AX NOMINAL +TOL -TOL MEAS DEV OUTTOL
M 3.2831 0.0050 0.0050 3.2831 0.0000 0.0000 ----#----
ASSIGN/V12=DIST1.MEAS+V6+V11
COMMENT/REPT,
"Pitch Diameter= " +V12
