Tertiary Datum doesn't constrain any degrees of freedom?

2023.1--Selecting Datum A as a plane; Datum B as a hole, Datum C as a hole.
"GEOMAJIC" States Datum C doesn't control any degree of freedom
Without Datum C, Datum B doesn't constrain the final degree of rotational freedom.
Am I wrong here?

Parents

brian.freeman over 1 year ago

Wouldn't PC-DMIS utilize Datum C as basically a 'point'; considering Datum B constrain 2 axis of translation?

PNT_A2 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.9783552,-0.0363233,-0.2755739>,<0,0.9991945,-0.0401288>
ACTL/<2.9783552,-0.0363233,-0.2755739>,<0,0.9991945,-0.0401288>
TARG/<2.9783552,-0.0113434,-0.2765771>,<0,0.9991945,-0.0401288>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT_A1 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.9783575,-0.0363216,-0.2755718>,<0,0.9991945,-0.0401288>
ACTL/<-2.9783575,-0.0363216,-0.2755718>,<0,0.9991945,-0.0401288>
TARG/<-2.9783575,-0.0113418,-0.276575>,<0,0.9991945,-0.0401288>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT_A3 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0.9997371,-0.0254643,-22.5902489>,<0,0.9995502,0.0299909>
ACTL/<0.9997371,-0.0004756,-22.5894991>,<0,0.9995502,0.0299909>
TARG/<0.9997371,-0.0004756,-22.5894991>,<0,0.9995502,0.0299909>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
CIR_C =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>,0.25
ACTL/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>,0.25
TARG/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>
START ANG=0,END ANG=360
ANGLE VEC=<-1,-0.0000062,-0.0000001>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
CIR_B =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,0,0>,<0.000003,0.9990898,-0.0426563>,0.25
ACTL/<0,0,0>,<0.000003,0.9990898,-0.0426563>,0.25
TARG/<0,0,0>,<0.000003,0.9990898,-0.0426563>
START ANG=0,END ANG=360
ANGLE VEC=<-1,0.000003,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
A4 =ALIGNMENT/START,RECALL:A3,LIST=YES
ALIGNMENT/ITERATE
PNT TARGET RAD=0.002,START LABEL=L1,FIXTURE TOL=0,ERROR LABEL=
MEAS ALL FEAT=ALWAYS,MAX ITERATIONS=5,LEVEL AXIS=YAXIS,ROTATE AXIS=XAXIS,ORIGIN AXIS=ZAXIS
LEVEL=PNT_A1,PNT_A2,PNT_A3,,
ROTATE=CIR_B,CIR_C,,
ORIGIN=CIR_B,,
ALIGNMENT/END
PLN_A =FEAT/PLANE,CARTESIAN,OUTLINE,NO,LEAST_SQR
THEO/<0.3332449,-0.0327031,-7.7137982>,<0.0000003,0.9999999,0.0004866>
ACTL/<0.333245,-0.0327031,-7.7137982>,<0.0000003,0.9999999,0.0004866>
CONSTR/PLANE,BF,PNT_A1,PNT_A2,PNT_A3,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
LIN_BC =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<0,0.000119,-22.6093018>,<0,-0.0000053,1>
ACTL/<0,0.000119,-22.6093018>,<0,-0.0000053,1>
CONSTR/LINE,BF,3D,CIR_C,CIR_B,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
A_ABC =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/LEVEL,YPLUS,PLN_A
ALIGNMENT/ROTATE,ZPLUS,TO,LIN_BC,ABOUT,YPLUS
ALIGNMENT/TRANS,YAXIS,PLN_A
ALIGNMENT/TRANS,XAXIS,CIR_B
ALIGNMENT/TRANS,ZAXIS,CIR_B
ALIGNMENT/END

Reply

brian.freeman over 1 year ago

Wouldn't PC-DMIS utilize Datum C as basically a 'point'; considering Datum B constrain 2 axis of translation?

PNT_A2 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.9783552,-0.0363233,-0.2755739>,<0,0.9991945,-0.0401288>
ACTL/<2.9783552,-0.0363233,-0.2755739>,<0,0.9991945,-0.0401288>
TARG/<2.9783552,-0.0113434,-0.2765771>,<0,0.9991945,-0.0401288>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT_A1 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-2.9783575,-0.0363216,-0.2755718>,<0,0.9991945,-0.0401288>
ACTL/<-2.9783575,-0.0363216,-0.2755718>,<0,0.9991945,-0.0401288>
TARG/<-2.9783575,-0.0113418,-0.276575>,<0,0.9991945,-0.0401288>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT_A3 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0.9997371,-0.0254643,-22.5902489>,<0,0.9995502,0.0299909>
ACTL/<0.9997371,-0.0004756,-22.5894991>,<0,0.9995502,0.0299909>
TARG/<0.9997371,-0.0004756,-22.5894991>,<0,0.9995502,0.0299909>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
CIR_C =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>,0.25
ACTL/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>,0.25
TARG/<0,0.000119,-22.6093018>,<-0.0000062,0.9995608,0.0296358>
START ANG=0,END ANG=360
ANGLE VEC=<-1,-0.0000062,-0.0000001>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
CIR_B =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,0,0>,<0.000003,0.9990898,-0.0426563>,0.25
ACTL/<0,0,0>,<0.000003,0.9990898,-0.0426563>,0.25
TARG/<0,0,0>,<0.000003,0.9990898,-0.0426563>
START ANG=0,END ANG=360
ANGLE VEC=<-1,0.000003,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
A4 =ALIGNMENT/START,RECALL:A3,LIST=YES
ALIGNMENT/ITERATE
PNT TARGET RAD=0.002,START LABEL=L1,FIXTURE TOL=0,ERROR LABEL=
MEAS ALL FEAT=ALWAYS,MAX ITERATIONS=5,LEVEL AXIS=YAXIS,ROTATE AXIS=XAXIS,ORIGIN AXIS=ZAXIS
LEVEL=PNT_A1,PNT_A2,PNT_A3,,
ROTATE=CIR_B,CIR_C,,
ORIGIN=CIR_B,,
ALIGNMENT/END
PLN_A =FEAT/PLANE,CARTESIAN,OUTLINE,NO,LEAST_SQR
THEO/<0.3332449,-0.0327031,-7.7137982>,<0.0000003,0.9999999,0.0004866>
ACTL/<0.333245,-0.0327031,-7.7137982>,<0.0000003,0.9999999,0.0004866>
CONSTR/PLANE,BF,PNT_A1,PNT_A2,PNT_A3,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
LIN_BC =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
THEO/<0,0.000119,-22.6093018>,<0,-0.0000053,1>
ACTL/<0,0.000119,-22.6093018>,<0,-0.0000053,1>
CONSTR/LINE,BF,3D,CIR_C,CIR_B,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,WAVELENGTH=0
A_ABC =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/LEVEL,YPLUS,PLN_A
ALIGNMENT/ROTATE,ZPLUS,TO,LIN_BC,ABOUT,YPLUS
ALIGNMENT/TRANS,YAXIS,PLN_A
ALIGNMENT/TRANS,XAXIS,CIR_B
ALIGNMENT/TRANS,ZAXIS,CIR_B
ALIGNMENT/END

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