Constructed Circles Not Flush to CAD?

[ALousyUser]

Hello again. I'm trying to measure the OD of a part that is based off of the internal radius. Using auto points, I created 4 different constructed circles around the part. After that, I created another constructed circle piercing the 4 smaller constructed circles to find my OD and TP. The issue is that the 4 constructed circles I created (BEST FIT) from the points, aren't touching the CAD where I picked points. They're floating in space. The result? An OD that's bigger than expected. If this is a bit confusing, I've attached both a screenshot and the code.

What I'm asking is: why did this happen? And is there a workaround?

PLN1 =FEAT/PLANE,CARTESIAN,TRIANGLE
THEO/<0.7346,5.4997,0>,<0,0,1>
ACTL/<54.2058,26.9191,-600.8362>,<0.0000322,0.0000177,1>
MEAS/PLANE,3
HIT/BASIC,NORMAL,<-32.1628,17.5168,0>,<0,0,1>,<21.7185,42.562,-600.8354>,USE THEO=YES
HIT/BASIC,NORMAL,<0.2397,-22.2706,0>,<0,0,1>,<52.3567,-3.1298,-600.8356>,USE THEO=YES
HIT/BASIC,NORMAL,<34.127,21.253,0>,<0,0,1>,<88.5421,41 .3252,-600.8375>,USE THEO=YES
ENDMEAS/
CIR1 =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,1.0173>,<-0.000529,0.0004914,0.9999997>,65.7468,0
ACTL/<53.8954,19.2729,-600.4487>,<0,0,1>,65.7474,0
MEAS/CIRCLE,3,ZPLUS
HIT/BASIC,NORMAL,<-2.0064,32.8123,1.4554>,<-0.0610273,0.998136,-0.0005227>,<75.6149,43.9498,-600.4136>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<-24.2161,-22.2315,0.3788>,<-0.7366581,-0.6762654,-0.0000574>,<24.8765,3.8268,-600.4069>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<32.7558,-2.777,1.2173>,<0.996425,-0.0844798,0.0005686>,<78.0653,-3.0093,-600.5255>,USE THEO=YES
ENDMEAS/
LIN1 =FEAT/LINE,CARTESIAN,UNBOUNDED
THEO/<40.4368,-22.3074,-1.3868>,<0,0.9999999,-0.0004914>
ACTL/<94.2923,-3.2834,-601.861>,<0.0018599,0.9999983,0>
MEAS/LINE,2,ZPLUS
HIT/BASIC,NORMAL,<40.4368,-22.3074,-1.2861>,<0.9999999,0.0000003,0.000529>,<94.2923,-3.2834,-602.2343>,USE THEO=YES
HIT/BASIC,NORMAL,<40.4369,20.8901,-1.5088>,<0.9999999,0.0000003,0.000529>,<94.3687,37 .7992,-601.4876>,USE THEO=YES
ENDMEAS/
A1 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN1
ALIGNMENT/ROTATE,YPLUS,TO,LIN1,ABOUT,ZPLUS
ALIGNMENT/TRANS,XAXIS,CIR1
ALIGNMENT/TRANS,YAXIS,CIR1
ALIGNMENT/TRANS,ZAXIS,PLN1
ALIGNMENT/END
MODE/DCC
CLEARP/ZPLUS,10,ZPLUS,0,ON
PREHIT/2
RETRACT/2
MOVE/CLEARPLANE
PLN2 =FEAT/PLANE,CARTESIAN,TRIANGLE
THEO/<-2.0026,1.3024,0.021>,<0.0007589,0.0008253,0.999999 4>
ACTL/<-2.0049,1.2983,0.0292>,<0.0011729,0.0002569,0.99999 93>
MEAS/PLANE,3
HIT/BASIC,NORMAL,<20.0072,1.9447,0.0038>,<0.0007589,0. 0008253,0.9999994>,<20.0044,1.9416,0.0032>,USE THEO=YES
HIT/BASIC,NORMAL,<-15.6679,15.675,0.0195>,<0.0007589,0.0008253,0.9999 994>,<-15.67,15.672,0.0415>,USE THEO=YES
HIT/BASIC,NORMAL,<-10.3471,-13.7125,0.0397>,<0.0007589,0.0008253,0.9999994>,<-10.349,-13.7186,0.0428>,USE THEO=YES
ENDMEAS/
MOVE/CLEARPLANE
CIR2 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,0>,<0,0,1>,65.7,0
ACTL/<0.0005,-0.0024,0>,<0,0,1>,65.7484,0
TARG/<0,0,0>,<0,0,1>
START ANG=0,END ANG=360
ANGLE VEC=<1,0,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=7,DEPTH=0.75,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
MOVE/CLEARPLANE
A2 =ALIGNMENT/START,RECALL:A1,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN2
ALIGNMENT/ROTATE,YPLUS,TO,LIN1,ABOUT,ZPLUS
ALIGNMENT/TRANS,XAXIS,CIR2
ALIGNMENT/TRANS,YAXIS,CIR2
ALIGNMENT/TRANS,ZAXIS,PLN2
ALIGNMENT/END
MOVE/CLEARPLANE
DATDEF/FEATURE=PLN2,A
DATDEF/FEATURE=CIR2,B
PNT1 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-30.7811,0,2.2627>,<-0.7209985,0.00178,0.6929343>
ACTL/<-30.9146,-0.0052,2.3855>,<-0.7209985,0.00178,0.6929343>
TARG/<-30.7811,0,2.2627>,<-0.7209985,0.00178,0.6929343>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT2 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-31.0385,0,2.0696>,<-0.4636676,0.0005564,0.8860091>
ACTL/<-31.1305,-0.0032,2.2408>,<-0.4636676,0.0005564,0.8860091>
TARG/<-31.0385,0,2.0696>,<-0.4636676,0.0005564,0.8860091>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT3 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-31.3402,0,1.9688>,<-0.1619855,-0.0004898,0.986793>
ACTL/<-31.3688,-0.0039,2.1544>,<-0.1619855,-0.0004898,0.986793>
TARG/<-31.3402,0,1.9688>,<-0.1619855,-0.0004898,0.986793>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR3 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<-31.5023,0.0003,2.9559>,<0.0004295,-0.9999998,0.0005457>,2.0007
ACTL/<-31.6074,-0.0639,3.1853>,<0.0237534,-0.99834,-0.05247>,2.1195
CONSTR/CIRCLE,BF,3D,PNT3,PNT2,PNT1,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT4 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-30.7834,2.2585>,<-0.0004814,-0.7190152,0.6949942>
ACTL/<-0.0031,-30.921,2.3973>,<-0.0004814,-0.7190152,0.6949942>
TARG/<0,-30.7834,2.2585>,<-0.0004814,-0.7190152,0.6949942>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT5 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-31.0434,2.065>,<-0.0006854,-0.4590501,0.8884101>
ACTL/<-0.0018,-31.1329,2.2549>,<-0.0006854,-0.4590501,0.8884101>
TARG/<0,-31.0434,2.065>,<-0.0006854,-0.4590501,0.8884101>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT6 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-31.3358,1.9674>,<-0.0007432,-0.1666161,0.9860216>
ACTL/<-0.0027,-31.3702,2.1683>,<-0.0007432,-0.1666161,0.9860216>
TARG/<0,-31.3358,1.9674>,<-0.0007432,-0.1666161,0.9860216>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR4 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<0.0002,-31.5025,2.9534>,<-1,-0.0000494,0.0002525>,1.9999
ACTL/<-0.0489,-31.6092,3.1923>,<-0.9989876,0.019622,-0.0404807>,2.105
CONSTR/CIRCLE,BF,3D,PNT6,PNT5,PNT4,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT7 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<30.7107,0,2.3783>,<0.7807968,-0.0160692,0.6245783>
ACTL/<30.8695,0.0005,2.5012>,<0.7807968,-0.0160692,0.6245783>
TARG/<30.7107,0,2.3783>,<0.7807968,-0.0160692,0.6245783>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT8 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<30.9638,0,2.1544>,<0.5290924,-0.0099767,0.8485056>
ACTL/<31.0812,-0.0011,2.3446>,<0.5290924,-0.0099767,0.8485056>
TARG/<30.9638,0,2.1544>,<0.5290924,-0.0099767,0.8485056>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT9 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<31.2576,0,2.0308>,<0.2346025,-0.0052174,0.9720774>
ACTL/<31.3044,-0.0032,2.2503>,<0.2346025,-0.0052174,0.9720774>
TARG/<31.2576,0,2.0308>,<0.2346025,-0.0052174,0.9720774>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR5 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<31.4982,-0.0016,3.0137>,<-0.0016013,0.9999942,0.0029905>,2.0239
ACTL/<31.6066,-0.0179,3.2766>,<0.0121724,0.9998626,0.0112556>,2.1 4
CONSTR/CIRCLE,BF,3D,PNT9,PNT8,PNT7,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT10 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,30.7064,2.3938>,<-0.0007956,0.7911254,0.6116535>
ACTL/<-0.0025,30.8526,2.5079>,<-0.0007956,0.7911254,0.6116535>
TARG/<0,30.7064,2.3938>,<-0.0007956,0.7911254,0.6116535>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT11 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,31.0183,2.1278>,<-0.0010264,0.4792489,0.8776784>
ACTL/<-0.0012,31.1139,2.3165>,<-0.0010264,0.4792489,0.8776784>
TARG/<0,31.0183,2.1278>,<-0.0010264,0.4792489,0.8776784>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT12 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,31.334,2.0189>,<-0.0008953,0.1634938,0.986544>
ACTL/<-0.0004,31.3601,2.224>,<-0.0008953,0.1634938,0.986544>
TARG/<0,31.334,2.0189>,<-0.0008953,0.1634938,0.986544>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR7 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<0.0004,31.4975,3.0054>,<-0.9999999,0.0002116,0.0004011>,1.9999
ACTL/<-0.0031,31.6141,3.2739>,<0.9999884,-0.0032085,0.0035991>,2.1603
CONSTR/CIRCLE,BF,3D,PNT12,PNT11,PNT10,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
CIR8 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<-0.002,-0.0025,2.9821>,<-0.0009169,-0.0008248,0.9999992>,63.0003
ACTL/<-0.0004,0.0024,3.2321>,<-0.001444,-0.0012902,0.9999981>,63.2187
CONSTR/CIRCLE,BF,3D,CIR7,CIR5,CIR4,CIR3,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0

[UKCMM]

Is there a reason why you are taking points and not just using Auto circles and I would change the 3D constructed to 2D.

[ALousyUser]

Mike Ruff. I see, ok. Thanks for your input, I'll redo the program tomorrow with everyone's critique in mind.

[UKCMM]

A 2D feature such as a circle can have errors if the point are staggered at different heights on the circle and can end up elliptical giving false size. It is best to resolve then to a correct Workplane as 2D circles.

I must admit I am having problems understanding your setup.

Your Alignment would suggest you are working in the Z plus Workplane but the circles you are trying to create are In the Y Workplane, I do not see any probe angle change or Workplane change.

Also why are you using the manual line in the DCC alignment.

[KIRBSTER269]

I'm with you on this UKCMM but until he straightens up those features, your solution won't even work

[KIRBSTER269]

Cir1 is not squared up, Lin1 is not straight, Pln2 is not flat, straighten up the THEO' s maybe you get better numbers and your points will hit?

[ALousyUser]

Gonna have to write a new program; there are a few things I need to change. By the way, if there's a circular part with no straight features, would it be acceptable to pick a line (for alignment purposes) using one of the straight edges of the 1-2-3 block its sitting on? That's what I did here, and I think that's throwing things off. How would you align a purely circular/cylindrical part with no angular/location call outs?

I was instructed by one of the members around here not to use a point as an aligning method.

[KIRBSTER269]

even if you don't have a CAD model and you have to take manual hits, you square it as much as you possibly can, your 123 block is technically square "PERFECT" but not really, PC-DMIS will take those perfect square hits and tell you what it actually is, but if you tell it to take uneven hits or hits at different levels it thinks every part is uneven, crooked, and such, it will take crummy hits, then it calculates that a crummy part and the crummy hits and will give even worse readings. if the part doesn't have a flat surface or anything straight maybe use Iterative alignment, but you have a cylinder, so that Cylinder has a top, create a plane on top, straighten out the THEO's even if it isn't perfect level to it and your cylinder can be your X and Y. If you laid the part out manually do you say "this thing don't lay flat, let me take a hammer and knock some notches on the table" ? when you don't square it up, that's pretty much what you are doing virtually.

[Douglas]

Every program at my employer was a learn program with nominals being the measured result of the part programmed from... last guy told me he didn't like auto features, which I immediately knew meant he could not figure them out, and of course he never went back to make nominals match drawing nominals. A few times I thought my head would explode over his failure to clean up the nominals

I cringe every time people say clean up the THEO... it has been a nightmare

[Mike Ruff]

Are you sure you're using the correct probe?

Are you sure it's calibrated?

Have you verified that the feature is actually machined correctly with something besides the CMM?

It looks like you have a small arc angle, which can make a deviation of .0009" look like the radius is out by .05"

[ALousyUser]

Yes, I've physically checked a few features and they're good. For the radius, I checked it on the optical comparator. I calibrated the probe tip (0.3mmx10mm) yesterday, and got a STD DEV of 0.0005". I didn't think to check the THEOs vs the ACTLs. They're all over the place. Gonna have to write a new program.

[gibsonridge]

i personally would suggest using a bit larger probe than a .3mm

[ALousyUser]

The radius I'm picking points off of, are theoretically R1.0mm, so it's better for me to use the 0.3mm probe tip.

[ALousyUser]

A 2D feature such as a circle can have errors if the point are staggered at different heights on the circle and can end up elliptical giving false size. It is best to resolve then to a correct Workplane as 2D circles.

I must admit I am having problems understanding your setup.

Your Alignment would suggest you are working in the Z plus Workplane but the circles you are trying to create are In the Y Workplane, I do not see any probe angle change or Workplane change.

Also why are you using the manual line in the DCC alignment.

UKCMM thanks a ton for the feedback.

1. I'm having a tough time understanding why I should be working in the Y workplane since the circles I'm trying to construct, revolve around the Z-axis (this is the same axis the part is revolved around). If I were to go ahead and construct circles using the points I picked, I would be using both the X and Y workplanes (view screenshot for an overview of the part and features).

2. As you can see, the part is circular in nature, so I have no straight lines to pick off of for alignment purposes except for the 1-2-3 block its sitting on. What would you suggest I do for the aligning portion of the DCC alignment?

I'm coming in tomorrow to do an overhaul and see where I get.

[KIRBSTER269]

If that's the part there really is no need for a line. make a flat plane, maybe from the surface plate, IJK 0,0,1 and Level it and Origin it. make a cylinder or circle Origin it to X and Y, Do a DCC alignment the same way and start measuring it.

[KIRBSTER269]

even if you do manual hits, make all the hits in the feature at the same height in Z, if its 0 then change all the hits to 0, if it's -24.753, then change all the hits to -24.753 if the IJK's are 0.001234, 0002453, 0.99999875, then change it to 0,0,1 PC-DMIS will give you the correct numbers in the actuals.

[UKCMM]

I was not suggesting you should be in the Y workplane I was making the comment that your constructed circles have vectors for a Y axis circle and as you had not changed workplane or probe then something did not add up with this setup.

[ALousyUser]

So here's a summary of what I did differently this morning compared to the first program I created yesterday:

1. I squared up my features (I think) and aligned it without using a line this time (per the advice from KIRBSTER269). Previously, I didn't know this was possible. I always thought you had to generally follow the 3, 2, 1 alignment rule.

2. I created the first series of points for one of the smaller circles (see attached screenshot), took note of the coordinates in the X, Y, and Z axis and then copied those same points (changing signs where necessary) to the other 3 clusters so that they're all at the same height and distance from the origin.

3. Cleaned up my THEOs (except for PLN1 and CIR1, need feedback on why the ACTLs are so far out from the THEOs. Machine coordinates?).

4. The comparator says the 63mm OD I'm trying to measure is 63.128mm (+/-0.13), but I'm getting 63.297mm and the TP is out by 0.1084mm).

I'm clearly missing something here and I'm just banging my head against the wall at this point.

PLN1 =FEAT/PLANE,CARTESIAN,TRIANGLE
THEO/<0.1888,2.4309,0>,<0,0,1>
ACTL/<54.9798,16.6807,-596.7695>,<0.0000824,-0.0005317,0.9999999>
MEAS/PLANE,3
HIT/BASIC,NORMAL,<-8.2087,25.512,0.0095>,<0,0,1>,<27.5121,17.8319,-596.7666>,USE THEO=YES
HIT/BASIC,NORMAL,<-17.3744,-20.0396,-0.0155>,<0,0,1>,<73.0528,38.0213,-596.7596>,USE THEO=YES
HIT/BASIC,NORMAL,<26.1496,1.8203,0.006>,<0,0,1>,<64.37 45,-5.8112,-596.7822>,USE THEO=YES
ENDMEAS/
CIR1 =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,-3.3>,<0,0,1>,65.7491,0
ACTL/<53.9556,19.0061,-599.8541>,<0,0,1>,65.749,0
MEAS/CIRCLE,3,ZPLUS
HIT/BASIC,NORMAL,<32.8299,1.7135,-3.3>,<0.9986407,0.0521215,0>,<52.1706,-13.8199,-599.8145>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<-19.3398,26.584,-3.3>,<-0.5882923,0.8086484,0>,<37.9212,47.705,-599.8278>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<-16.7595,-28.2817,-3.3>,<-0.509801,-0.8602924,0>,<86.6253,22.67,-599.92>,USE THEO=YES
ENDMEAS/
A1 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN1
ALIGNMENT/TRANS,ZAXIS,PLN1
ALIGNMENT/TRANS,XAXIS,CIR1
ALIGNMENT/TRANS,YAXIS,CIR1
ALIGNMENT/END
MODE/DCC
CLEARP/ZPLUS,10,ZPLUS,0,ON
PREHIT/2
RETRACT/2
MOVE/CLEARPLANE
PLN2 =FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,NONE
THEO/<0,0,0>,<0,0,1>
ACTL/<0.001,0.0048,-0.003>,<-0.0001895,0.0000647,1>
TARG/<0,0,0>,<0,0,1>
ANGLE VEC=<1,-0.0000004,0>,RADIAL
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=4,NUMRINGS=1
SPACER=27
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
CIR2 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,-3.9>,<0,0,1>,65.7,0
ACTL/<-0.0013,-0.0004,-3.9>,<0,0,1>,65.7515,0
TARG/<0,0,-3.9>,<0,0,1>
START ANG=0,END ANG=360
ANGLE VEC=<1,-0.0000004,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=7,DEPTH=0.75,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
A2 =ALIGNMENT/START,RECALL:A1,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN2
ALIGNMENT/TRANS,ZAXIS,PLN2
ALIGNMENT/TRANS,XAXIS,CIR2
ALIGNMENT/TRANS,YAXIS,CIR2
ALIGNMENT/END
MOVE/CLEARPLANE
DATDEF/FEATURE=PLN2,A
DATDEF/FEATURE=CIR2,B
PNT1 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-30.6628,-1.4469>,<-0.0000002,-0.8372086,0.5468837>
ACTL/<0.0005,-30.7253,-1.4028>,<-0.0000002,-0.8372086,0.5468837>
TARG/<0,-30.6628,-1.4469>,<-0.0000002,-0.8372086,0.5468837>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT2 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-30.8698,-1.6764>,<-0.0000001,-0.6302018,0.7764314>
ACTL/<0.0015,-30.919,-1.6177>,<-0.0000001,-0.6302018,0.7764314>
TARG/<0,-30.8698,-1.6764>,<-0.0000001,-0.6302018,0.7764314>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT3 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,-31.1499,-1.8367>,<-0.0000001,-0.3500817,0.9367192>
ACTL/<0.0027,-31.1611,-1.7717>,<-0.0000001,-0.3500817,0.9367192>
TARG/<0,-31.1499,-1.8367>,<-0.0000001,-0.3500817,0.9367192>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR3 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,YES
THEO/<0,-31.5,-0.9>,<1,-0.0000002,0>,2
ACTL/<0.005,-31.6091,-0.8004>,<0.9999837,0.0056836,0.0005307>,2.1393
CONSTR/CIRCLE,BF,3D,PNT1,PNT2,PNT3,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT4 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<30.6628,0,-1.4469>,<0.8284785,-0.0000002,0.5600208>
ACTL/<30.7327,0.0082,-1.4091>,<0.8284785,-0.0000002,0.5600208>
TARG/<30.6628,0,-1.4469>,<0.8284785,-0.0000002,0.5600208>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT5 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<30.8698,0,-1.6764>,<0.6135166,-0.0000001,0.7896818>
ACTL/<30.9218,0.0077,-1.6146>,<0.6135166,-0.0000001,0.7896818>
TARG/<30.8698,0,-1.6764>,<0.6135166,-0.0000001,0.7896818>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT6 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<31.1499,0,-1.8367>,<0.3362587,-0.0000001,0.9417697>
ACTL/<31.1705,0.0072,-1.7689>,<0.3362587,-0.0000001,0.9417697>
TARG/<31.1499,0,-1.8367>,<0.3362587,-0.0000001,0.9417697>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR4 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,YES
THEO/<31.5,0,-0.9>,<0.0000002,1,0>,2
ACTL/<31.5977,0.0098,-0.8032>,<0.0003322,0.9999957,-0.0029095>,2.112
CONSTR/CIRCLE,BF,3D,PNT4,PNT5,PNT6,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT7 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,30.6628,-1.4469>,<0.0000002,0.7972843,0.6036039>
ACTL/<0.0027,30.7273,-1.4072>,<0.0000002,0.7972843,0.6036039>
TARG/<0,30.6628,-1.4469>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT8 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,30.8698,-1.6764>,<0.0000002,0.7972843,0.6036039>
ACTL/<0.0034,30.9367,-1.6241>,<0.0000002,0.7972843,0.6036039>
TARG/<0,30.8698,-1.6764>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT9 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<0,31.1499,-1.8367>,<0.0000002,0.7972843,0.6036039>
ACTL/<0.0027,31.2222,-1.7695>,<0.0000002,0.7972843,0.6036039>
TARG/<0,31.1499,-1.8367>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR5 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,YES
THEO/<0,31.5,-0.9>,<1,-0.0000002,0>,2
ACTL/<-0.0092,31.5004,-0.8704>,<0.9999104,0.0078525,0.0108391>,1.8825
CONSTR/CIRCLE,BF,3D,PNT7,PNT8,PNT9,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
MOVE/CLEARPLANE
PNT10 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-30.6628,0,-1.4469>,<0.0000002,0.7972843,0.6036039>
ACTL/<-30.6801,0.3637,-1.1659>,<0.0000002,0.7972843,0.6036039>
TARG/<-30.6628,0,-1.4469>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT11 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-30.8698,0,-1.6764>,<0.0000002,0.7972843,0.6036039>
ACTL/<-30.8853,0.2807,-1.4564>,<0.0000002,0.7972843,0.6036039>
TARG/<-30.8698,0,-1.6764>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
PNT12 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<-31.1499,0,-1.8367>,<0.0000002,0.7972843,0.6036039>
ACTL/<-31.1614,0.1736,-1.6898>,<0.0000002,0.7972843,0.6036039>
TARG/<-31.1499,0,-1.8367>,<0.0000002,0.7972843,0.6036039>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
CIR6 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,YES
THEO/<-31.5002,0,-0.9>,<0.0000002,1,0>,2
ACTL/<-31.8853,-0.0521,-0.4253>,<-0.3411202,0.9396145,-0.0275984>,2.9489
CONSTR/CIRCLE,BF,3D,PNT10,PNT11,PNT12,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
CIR7 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,YES
THEO/<0,0,-0.9>,<0,0,1>,63
ACTL/<-0.1442,-0.0543,-0.7248>,<0,0,1>,63.2966
CONSTR/CIRCLE,BF,2D,CIR3,CIR4,CIR5,CIR6,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
FCFLOC1 =POSITION : CIR7
FEATCTRLFRAME/SHOWNOMS=NO,SHOWPARAMS=NO,SHOWEXPANDED=NO
SIZE TOLERANCES/1,DIAMETER,63,0.13,0.13
PRIMARY DIMENSION/POSITION,DIAMETER,0.2, ,A,B, ,
NOTE/FCFLOC1
FEATURES/CIR7,,

[UKCMM]

Your point nominal vectors are still out I am going to assume you are clicking on the Cad model to get the hit positions but are very slightly off centre. The feature you are measuring is a section of a torus and I think later versions of DMIS have that as one of the features it can measure.

Another problem I see is that the spread of the hits is not making best use of the measurable radius, one hit in each group should be close to the radial distance of the diameter 63.00 that you are trying to measure but you are taking a hit at 31.1499 that's a big section of the small radius you are missing.

You are still using 3D circle and not 2D with the correct workplane.

Rather than taking random points of the CAD with the errors that can create why not work out where the auto circles should be you have all the information.

If I was checking this the first thing I would do is set the Z datum on the flange face that the radius runs out onto this would better control the hit positions.

As an example to create your cir3 I would change workplane to X Plus or Minus, open the Auto circle dialog box and enter the circle position X 0.0 , Y -31.5, Z 1.0. Vector I 1.0, J 0.0, K 0.0.
I would set the angler start vector at 0,0,-1 this will place the start point of the circle at the flange face. now just adjust the start and end points to allow for where the hits go I would allow approx. 5 degrees in from the start and finish point of the radius. You can easily trig this out or just guess your call just remember with a small arc you need to us as much as possible to get reliable data.

Do this for all 4 radius remembering to set the correct workplane.

Change back to the Z workplane and construct a 2D circle from the 4 circles

I notice that the points that make cir6 are way off in the Y should be 0.0 but actuals are of by 0.36 as you are measuring on a surface that curves in all directions this will have a big effect on the circle generated . That is what you see in the cir6 result with the diameter being 2.95.

There can be numerous reasons for the probing error such as.
Part moved as not secured.
Dirt on the probe or part.
Damaged styli.
Programme not re-run after cleaning up nominals.

[ALousyUser]

UKCMM You're correct in your assumption that I'm clicking on the CAD model to create hit positions. This method was pretty time-consuming compared to your suggestions for a different method, which I put to use as seen below:

I adjusted the XYZ/IJK values where appropriate after changing to the correct workplanes. Beyond checking the physical styli, probe head, and making sure the part was secured, I'm not sure what else I can do since the measured diameters of the 4 auto circles are pretty big (THEO ID = 2, ACTL ID = 2.147 - 2.262).

Measured OD: 63.259mm
TP: 0.033mm

I am confident that the TP is acceptable (part was made in 1 operation) and I confirmed the OD was good with the optical comparator. The small arc/"large" radius phenomenon is a real pain. Would you pass this part with what is shown in the code here? Why or why not?

By the way, I appreciate the responses. They've been very helpful.

PLN1 =FEAT/PLANE,CARTESIAN,TRIANGLE
THEO/<0.1888,2.4309,0>,<0,0,1>
ACTL/<51.5749,16.1533,-596.7669>,<-0.0000445,-0.0006882,0.9999998>
MEAS/PLANE,3
HIT/BASIC,NORMAL,<-8.2087,25.512,0.0095>,<0,0,1>,<27.6012,19.744,-596.7655>,USE THEO=YES
HIT/BASIC,NORMAL,<-17.3744,-20.0396,-0.0155>,<0,0,1>,<74.1379,36.479,-596.7519>,USE THEO=YES
HIT/BASIC,NORMAL,<26.1496,1.8203,0.006>,<0,0,1>,<52.98 55,-7.7632,-596.7833>,USE THEO=YES
ENDMEAS/
CIR1 =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,-3.3>,<0,0,1>,65.7491,0
ACTL/<53.9611,19.0076,-599.4814>,<0,0,1>,65.7493,0
MEAS/CIRCLE,3,ZPLUS
HIT/BASIC,NORMAL,<32.8299,1.7135,-3.3>,<0.9986407,0.0521215,0>,<53.4943,-13.8637,-599.5098>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<-19.3398,26.584,-3.3>,<-0.5882923,0.8086484,0>,<30.5076,42.0441,-599.4598>,USE THEO=YES
MOVE/CIRCULAR
HIT/BASIC,NORMAL,<-16.7595,-28.2817,-3.3>,<-0.509801,-0.8602924,0>,<86.5397,23.4091,-599.4746>,USE THEO=YES
ENDMEAS/
A1 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN1
ALIGNMENT/TRANS,ZAXIS,PLN1
ALIGNMENT/TRANS,XAXIS,CIR1
ALIGNMENT/TRANS,YAXIS,CIR1
ALIGNMENT/END
MODE/DCC
CLEARP/ZPLUS,10,ZPLUS,0,ON
PREHIT/2
RETRACT/2
MOVE/CLEARPLANE
PLN2 =FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,NONE
THEO/<0,0,-1.9>,<0,0,1>
ACTL/<-0.0011,-0.0114,-1.8793>,<-0.0000629,0.0001455,1>
TARG/<0,0,-1.9>,<0,0,1>
ANGLE VEC=<1,0.0000002,0>,RADIAL
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=4,NUMRINGS=1
SPACER=32
AVOIDANCE MOVE=NO,DISTANCE=1.778
SHOW HITS=NO
MOVE/CLEARPLANE
CIR2 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,-2.5>,<0,0,-1>,65.7,0
ACTL/<-0.0022,-0.0035,-2.5>,<0,0,-1>,65.7493,0
TARG/<0,0,-2.5>,<0,0,-1>
START ANG=0,END ANG=360
ANGLE VEC=<-1,-0.0000002,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=7,DEPTH=0.75,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
A2 =ALIGNMENT/START,RECALL:A1,LIST=YES
ALIGNMENT/LEVEL,ZPLUS,PLN2
ALIGNMENT/TRANS,ZAXIS,PLN2
ALIGNMENT/TRANS,XAXIS,CIR2
ALIGNMENT/TRANS,YAXIS,CIR2
ALIGNMENT/END
WORKPLANE/XPLUS
MOVE/CLEARPLANE
DATDEF/FEATURE=PLN2,A
DATDEF/FEATURE=CIR2,B
CIR3 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,31.5,1>,<1,0,0>,2
ACTL/<0,31.6406,1.114>,<1,0,0>,2.2374
TARG/<0,31.5,1>,<1,0,0>
START ANG=310,END ANG=-10
ANGLE VEC=<0,0,-1>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=6,DEPTH=0,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
MOVE/CLEARPLANE
CIR4 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<0,-31.5,1>,<1,0,0>,2
ACTL/<0,-31.6268,1.1081>,<1,0,0>,2.2183
TARG/<0,-31.5,1>,<1,0,0>
START ANG=10,END ANG=-310
ANGLE VEC=<0,0,-1>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=6,DEPTH=0,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
WORKPLANE/YPLUS
MOVE/CLEARPLANE
CIR5 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<31.5,0,1>,<0,1,0>,2
ACTL/<31.6344,0,1.1164>,<0,1,0>,2.2255
TARG/<31.5,0,1>,<0,1,0>
START ANG=10,END ANG=-310
ANGLE VEC=<0,0,-1>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=6,DEPTH=0,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
MOVE/CLEARPLANE
CIR6 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
THEO/<-31.5,0,1>,<0,1,0>,2
ACTL/<-31.6102,0,1.0809>,<0,1,0>,2.1441
TARG/<-31.5,0,1>,<0,1,0>
START ANG=310,END ANG=-10
ANGLE VEC=<0,0,-1>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=6,DEPTH=0,PITCH=0
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0
FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
SHOW HITS=NO
MOVE/CLEARPLANE
WORKPLANE/ZPLUS
CIR7 =FEAT/CIRCLE,CARTESIAN,IN,LEAST_SQR,NO
THEO/<0,0,1>,<0,0,1>,63
ACTL/<0.0121,0.0069,1.1049>,<0,0,1>,63.256
CONSTR/CIRCLE,BF,2D,CIR3,CIR4,CIR5,CIR6,,
OUTLIER_REMOVAL/OFF,3
FILTER/OFF,UPR=0
FCFLOC1 =POSITION : CIR7
FEATCTRLFRAME/SHOWNOMS=NO,SHOWPARAMS=NO,SHOWEXPANDED=NO
SIZE TOLERANCES/1,DIAMETER,63,0.13,0.13
PRIMARY DIMENSION/POSITION,DIAMETER,0.2, ,A,B, ,
NOTE/FCFLOC1
FEATURES/CIR7,,

[UKCMM]

All looks good my only change would be to use more of the arc so instead of starting at 10 degree I would use 5 degree and if you can move the end do that. I have also found that using 3 hits on small arc measurements can give better results.

[louisd]

have you entertained referencing the good ol' SMALL ARC white paper that Hexagon has on their knowledgebase?
In short, you set measured your 2d circle as FIXED RAD, origin locally to it, then remeasure the points, report PR.
repeat a few times and construct your torus from those points

https://support.hexagonmi.com/s/arti...-1528360401117
you will need to login to see it