对称度用于控制被测要素中心平面（ 或中心线） 的共面（ 或共线） 性误差。
分类： 对称度包括直线（ 中心线） 对平面， 平面（ 中心面） 对平面， 直线（ 中心线） 与直线三种情况； 前两种情况下， 公差带均为对称于基准（ 直线或平面） 配置的两个平行平面之间的区域； 第三种情况下要求构成被测中心线的两条直线与基准直线在同一个平面内， 其公差带为对称于基准直线配置的两条平行直线之间的区域。
1.首先测量圆柱，并把圆柱轴线设置成 Z 轴。
MODE/MAN
DID(D2L40)=DEVICE/STOR,'D2L40'
OPEN/DID(D2L40),SNS
S(A0B0)=SNSDEF/PROBE,INDEX,POL,0.0,0.0,0.0000,0.0000,1.0000,189.6500,2.0000
SNSLCT/SA(A0B0)
SNSET/RETRCT,2.0000
SNSET/APPRCH,2.0000
GEOALG/CYLNDR,LSTSQR
F(圆柱1)=FEAT/CYLNDR,INNER,CART,0,0,-14.4057,0,0,1.00000000,30.0000,13.3907
MEAS/CYLNDR,F(圆柱1),8
PTMEAS/CART,-1.0697,14.9618,-14.0675,0.07131177,-0.99745407,0
PTMEAS/CART,14.9372,-1.3712,-14.3516,-0.99581299,0.09141385,0
PTMEAS/CART,-3.0110,-14.6947,-13.3458,0.20073153,0.97964629,0
PTMEAS/CART,-14.6749,3.1062,-14.4057,0.97832357,-0.20708209,0
PTMEAS/CART,-14.7542,2.7044,-1.1731,0.98361246,-0.18029568,0
PTMEAS/CART,-0.8725,14.9746,-1.0151,0.05816609,-0.99830692,0
PTMEAS/CART,13.8529,5.7531,-1.3366,-0.92352398,-0.38354069,0
PTMEAS/CART,4.6808,-14.2510,-1.2282,-0.31205047,0.95006553,0
ENDMES
DATDEF/F(圆柱1),DAT(A_圆柱1)
D(坐标系1_S)=DATSET/DAT(A_圆柱1),ZDIR
SAVE/DA(坐标系1)
2.采集被测要素(圆1与圆2），利用“圆1”和“圆2”构造一个中分点。
SNSET/DEPTH,0
GEOALG/CIRCLE,LSTSQR
DMESW/COMAND,'CONST/SET_PROJ_VEC,FA(XY),1'
F(圆1)=FEAT/CIRCLE,INNER,CART,-20.0000,-26.0000,-1.2015,-0.02590842,-0.01299817,0.99957981,15.0000
MEAS/CIRCLE,F(圆1),4
PTMEAS/CART,-27.4807,-26.5373,-1.2015,0.99743025,0.07164426,0
PTMEAS/CART,-19.8884,-33.4992,-1.2015,-0.01487467,0.99988937,0
PTMEAS/CART,-12.8195,-23.8343,-1.2015,-0.95740323,-0.28875432,0
PTMEAS/CART,-20.0792,-18.5004,-1.2015,0.01055921,-0.99994425,0
ENDMES
SNSET/DEPTH,0
GEOALG/CIRCLE,LSTSQR
DMESW/COMAND,'CONST/SET_PROJ_VEC,FA(XY),1'
F(圆2)=FEAT/CIRCLE,INNER,CART,20.0000,-26.0000,-1.4098,0.03086542,-0.05242839,0.99814758,15.0000
MEAS/CIRCLE,F(圆2),4
PTMEAS/CART,12.5876,-27.1428,-1.4098,0.98832205,0.15237957,0
PTMEAS/CART,17.8972,-18.8008,-1.4098,0.28037469,-0.95989064,0
PTMEAS/CART,27.4958,-26.2519,-1.4098,-0.99943601,0.03358072,0
PTMEAS/CART,20.2173,-33.4969,-1.4098,-0.02896680,0.99958037,0
ENDMES
F(点1)=FEAT/POINT,CART,0.0003,-26.0042,-1.3037,0,0,1.00000000
CONST/POINT,F(点1),MIDPT,FA(圆1),FA(圆2)
3.用中分点到基准A上做垂射点(把上面的中点垂射到圆柱轴线上)
F(点2)=FEAT/POINT,CART,0,0,-1.3037,0.00001154,-1.00000000,0
CONST/POINT,F(点2),PROJPT,FA(点1),FA(圆柱1)
4.圆柱找正Z+，中分点和垂射点的连线绕Z+旋转到Y-，中分点确定X、
Y、Z的原点.
5.构造坐标平面YZ
6.评价对称度
$$ NET_DMIS_20160720
$$ MADE IN DE 2023-2-9 12:59:58
INCLUD/DMIS,'NET_DMIS_DEFINES.DMI'
INCLUD/DMIS,'VARDEFINE'
DMESW/COMAND,'PROBE_VAL/INIT'
UNITS/MM,ANGDEC
D(MACHINE)=DATSET/MCS
DMESW/COMAND,'COORDSYS/ALIGN'
WKPLAN/XYPLAN
PRCOMP/ON
PRCOMP/ON
FEDRAT/POSVEL,MMPS,300.0000
ACLRAT/POSACL,MMPSS,100.0000
FEDRAT/MESVEL,MMPS,20.0000
ACLRAT/MESACL,MMPSS,100.0000
SNSET/RETRCT,1.0000
SNSET/SEARCH,5.0000
SNSET/APPRCH,1.0000
DMESW/COMAND,'SNSET/MANRETRCT,2'
DMESW/COMAND,'REPORT/CLEAR'
MODE/MAN
DID(D2L40)=DEVICE/STOR,'D2L40'
OPEN/DID(D2L40),SNS
S(A0B0)=SNSDEF/PROBE,INDEX,POL,0.0,0.0,0.0000,0.0000,1.0000,189.6500,2.0000
SNSLCT/SA(A0B0)
SNSET/RETRCT,2.0000
SNSET/APPRCH,2.0000
GEOALG/CYLNDR,LSTSQR
F(圆柱1)=FEAT/CYLNDR,INNER,CART,0,0,-14.4057,0,0,1.00000000,30.0000,13.3907
MEAS/CYLNDR,F(圆柱1),8
PTMEAS/CART,-1.0697,14.9618,-14.0675,0.07131177,-0.99745407,0
PTMEAS/CART,14.9372,-1.3712,-14.3516,-0.99581299,0.09141385,0
PTMEAS/CART,-3.0110,-14.6947,-13.3458,0.20073153,0.97964629,0
PTMEAS/CART,-14.6749,3.1062,-14.4057,0.97832357,-0.20708209,0
PTMEAS/CART,-14.7542,2.7044,-1.1731,0.98361246,-0.18029568,0
PTMEAS/CART,-0.8725,14.9746,-1.0151,0.05816609,-0.99830692,0
PTMEAS/CART,13.8529,5.7531,-1.3366,-0.92352398,-0.38354069,0
PTMEAS/CART,4.6808,-14.2510,-1.2282,-0.31205047,0.95006553,0
ENDMES
DATDEF/F(圆柱1),DAT(A_圆柱1)
D(坐标系1_S)=DATSET/DAT(A_圆柱1),ZDIR
SAVE/DA(坐标系1)
SNSET/DEPTH,0
GEOALG/CIRCLE,LSTSQR
DMESW/COMAND,'CONST/SET_PROJ_VEC,FA(XY),1'
F(圆1)=FEAT/CIRCLE,INNER,CART,-20.0000,-26.0000,-1.2015,-0.02590842,-0.01299817,0.99957981,15.0000
MEAS/CIRCLE,F(圆1),4
PTMEAS/CART,-27.4807,-26.5373,-1.2015,0.99743025,0.07164426,0
PTMEAS/CART,-19.8884,-33.4992,-1.2015,-0.01487467,0.99988937,0
PTMEAS/CART,-12.8195,-23.8343,-1.2015,-0.95740323,-0.28875432,0
PTMEAS/CART,-20.0792,-18.5004,-1.2015,0.01055921,-0.99994425,0
ENDMES
SNSET/DEPTH,0
GEOALG/CIRCLE,LSTSQR
DMESW/COMAND,'CONST/SET_PROJ_VEC,FA(XY),1'
F(圆2)=FEAT/CIRCLE,INNER,CART,20.0000,-26.0000,-1.4098,0.03086542,-0.05242839,0.99814758,15.0000
MEAS/CIRCLE,F(圆2),4
PTMEAS/CART,12.5876,-27.1428,-1.4098,0.98832205,0.15237957,0
PTMEAS/CART,17.8972,-18.8008,-1.4098,0.28037469,-0.95989064,0
PTMEAS/CART,27.4958,-26.2519,-1.4098,-0.99943601,0.03358072,0
PTMEAS/CART,20.2173,-33.4969,-1.4098,-0.02896680,0.99958037,0
ENDMES
F(点1)=FEAT/POINT,CART,0.0003,-26.0042,-1.3037,0,0,1.00000000
CONST/POINT,F(点1),MIDPT,FA(圆1),FA(圆2)
F(点2)=FEAT/POINT,CART,0,0,-1.3037,0.00001154,-1.00000000,0
CONST/POINT,F(点2),PROJPT,FA(点1),FA(圆柱1)
DMESW/COMAND,'CONST/SET_PROJ_VEC,FA(XY),1'
F(直线1)=FEAT/LINE,UNBND,CART,0,0,-1.3037,0.00001154,-1.00000000,0,1.00000000,0.00001154,0
CONST/LINE,F(直线1),BF,FA(点2),FA(点1)
DATDEF/F(圆柱1),DAT(A_圆柱1)
D(坐标系2_S)=DATSET/DAT(A_圆柱1),ZDIR
D(坐标系2_R)=ROTATE/ZAXIS,FA(直线1),-YDIR
D(坐标系2_T)=TRANS/XORIG,FA(点2),YORIG,FA(点2),ZORIG,FA(点2)
DMESW/COMAND,'COORDSYS/CAD=PART'
SAVE/DA(坐标系2)
F(平面1)=FEAT/PLANE,CART,0,0,0,1.00000000,0,0
F(圆3)=FEAT/CIRCLE,INNER,CART,-20.0000,-26.0000,0,0,0,1.00000000,15.0000
CALL/EXTERN,DMIS,M(NETDMIS_AUTO_CIRCLE_1007),AUTOFIGURE,F(圆3),CIRCLE,INNER,CART,LSTSQR,-20.0000,-26.0000,$
0,0,0,1.00000000,15.0000,-1.00000000,0,0,4,-2.0000,0,0,0,0,360.0000,TOUCH,CIRCLE,0.3000,0,FALSE,FALSE,$
FALSE,10.0000,"",FALSE,FALSE,0,FA(VECBLD),10.0000,2.5000,3,XYPLAN,"",'7,0,0,0,0,3.0000,0,10','0,1,0,5.0000',$
"EXT3",ENDCAL
F(圆4)=FEAT/CIRCLE,INNER,CART,20.0000,-26.0000,0,0,0,1.00000000,15.0000
CALL/EXTERN,DMIS,M(NETDMIS_AUTO_CIRCLE_1007),AUTOFIGURE,F(圆4),CIRCLE,INNER,CART,LSTSQR,20.0000,-26.0000,$
0,0,0,1.00000000,15.0000,-1.00000000,0,0,4,-2.0000,0,0,0,0,360.0000,TOUCH,CIRCLE,0.3000,0,FALSE,FALSE,$
FALSE,10.0000,"",FALSE,FALSE,0,FA(VECBLD),10.0000,2.5000,3,XYPLAN,"",'7,0,0,0,0,3.0000,0,10','0,1,0,5.0000',$
"EXT3",ENDCAL
T(对称度1)=TOL/SYM,0.0500,FA(平面1),RFS
DMESW/COMAND,'OUTPUT/UNIT,DIMENSION/MM'
OUTPUT/FA(圆3),FA(圆4),TA(对称度1)
注意事项：1.区分被测要素与基准要素；
2.基准只能是直线或者平面，一般为构造的特征（例如中分线、中分面等）；
3.被测元素在测量时， 要求在构成被测中心要素（ 直线或平面） 的两个轮廓要素（ 直线或平面） 上采相同数量的测量点。
4.当这两个轮廓要素（ 直线或平面） 不平行时， 还进一步要求两侧轮廓要素（ 直线或平面）上相对应的测点间的连线应垂直与其中心要素（ 直线或平面） 。（被测面至少4个点,点5，6，7，8最好采用镜像的特征,然后切换到DCC自动运行一遍。）