I have a slight calibration issue. The CMM calibrates perfectly to the calibration probe, but does not calibrate to a boring gage set to 1.5743; it always shows undersized or oversized. Is this problem fixable? If so, how?
Calibration in the Wrong?
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I wouldn't compare the CMM to a bore gage. How many hits are you taking on it? How do you know you are hitting perfectly on it? How far off? What is the capability of your CMM?
There are a number of variables that need to be looked at.When in doubt, post code. A second set of eyes might see something you missed.
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Originally posted by John Kingston View PostI wouldn't compare the CMM to a bore gage. How many hits are you taking on it? How do you know you are hitting perfectly on it? How far off? What is the capability of your CMM?
There are a number of variables that need to be looked at.
The hits are relatively evenly spaced all around the part.
Everything else I'm not sure.
The boring gage is 1.5743, and the boring micrometer(or whatever you call it) calibrates to the boring gage just fine. My whole thing is: If the CMM measures a different number for a boring gage(which is precisely precise), how can I be sure the CMM is giving me the correct results?I feel a lot better now that I've lost my mind.
Global Activ
PCDMIS CAD ++3.5 MR2
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Originally posted by operator1 View PostThe CMM takes 3 rows of hits to make 3 circles; about 6 or 7 hits per circle.
The hits are relatively evenly spaced all around the part.
Everything else I'm not sure.
The boring gage is 1.5743, and the boring micrometer(or whatever you call it) calibrates to the boring gage just fine. My whole thing is: If the CMM measures a different number for a boring gage(which is precisely precise), how can I be sure the CMM is giving me the correct results?
The thing is, you don't say what kind or error you are getting. And 6 or 7 hits per row doesn't sound like a precise pattern etc.
Please do what James says and post code.Bill Jarrells
A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain
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Originally posted by operator1 View PostThe CMM takes 3 rows of hits to make 3 circles; about 6 or 7 hits per circle.
The hits are relatively evenly spaced all around the part.
Everything else I'm not sure.
The boring gage is 1.5743, and the boring micrometer(or whatever you call it) calibrates to the boring gage just fine. My whole thing is: If the CMM measures a different number for a boring gage(which is precisely precise), how can I be sure the CMM is giving me the correct results?
Have you taken my/other peoples advice and created a manual alignment that locks down the 6° of freedom cited in the papers I gave you? And then did you do this in DCC mode?sigpic
James Mannes
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Code:=alignment/start,recall:, List= Yes Alignment/end Loadprobe/rick1 Tip/t1a0b0, Shankijk=0, 0, 1, Angle=0 Mode/manual Workplane/zplus Loadprobe/rick1 Tip/t1a0b0, Shankijk=0, 0, 1, Angle=0 Prehit/ 0.075 Retract/ 0.055 Check/ 0.4724,1 Movespeed/ 80 Scanspeed/ 5 Fly/on,0.1181 Workplane/zplus Mode/dcc Move/point,9.403,4.7804,-26.0703 Move/point,9.6389,4.5946,-28.3462 Plane1 =feat/plane,rect Theo/9.387,4.5542,-28.7035,0.0004049,-0.0003886,0.9999998 Actl/9.387,4.5542,-28.6997,0.0002327,-0.0003199,0.9999999 Meas/plane,5 Hit/basic,10.3705,4.716,-28.7039,0.0004049,-0.0003886,0.9999998,10.3706,4.716,-28.6999,use Theo = Yes Hit/basic,9.862,3.8501,-28.704,0.0004049,-0.0003886,0.9999998,9.862,3.8501,-28.7,use Theo = Yes Hit/basic,8.8631,3.8502,-28.7036,0.0004049,-0.0003886,0.9999998,8.8631,3.8502,-28.6998,use Theo = Yes Hit/basic,8.5182,4.8233,-28.7031,0.0004049,-0.0003886,0.9999998,8.5182,4.8234,-28.6994,use Theo = Yes Hit/basic,9.321,5.5315,-28.7031,0.0004049,-0.0003886,0.9999998,9.321,5.5315,-28.6993,use Theo = Yes Endmeas/ Move/point,9.3206,4.775,-27.8987 Circle1 =feat/circle,rect,in,least_sqr Theo/9.3996,4.6063,-28.9924,0,0,1,1.5743 Actl/9.4192,4.6209,-28.9924,0,0,1,1.5768 Meas/circle,5,workplane Hit/basic,10.1814,4.697,-28.9924,-0.993331,-0.1152974,0,10.2036,4.6995,-28.9924,use Theo = Yes Hit/basic,9.4688,3.8221,-28.9924,-0.0878054,0.9961376,0,9.4676,3.8339,-28.9924,use Theo = Yes Hit/basic,8.6214,4.4888,-28.9924,0.9887999,0.1492472,0,8.6415,4.4919,-28.9924,use Theo = Yes Hit/basic,8.8771,5.195,-28.9924,0.6638055,-0.7479052,0,8.8755,5.1918,-28.9924,use Theo = Yes Hit/basic,9.9109,5.2049,-28.9924,-0.649424,-0.7604265,0,9.9266,5.2244,-28.9924,use Theo = Yes Endmeas/ Move/point,9.4911,4.9548,-28.9825 Circle2 =feat/circle,rect,in,least_sqr Theo/9.3996,4.6064,-29.352,0,0,1,1.5743 Actl/9.4192,4.6211,-29.352,0,0,1,1.5755 Meas/circle,5,workplane Hit/basic,10.1829,4.6807,-29.352,-0.9955311,-0.094434,0,10.2046,4.681,-29.352,use Theo = Yes Hit/basic,9.7902,3.9227,-29.352,-0.4960448,0.868297,0,9.7855,3.9237,-29.352,use Theo = Yes Hit/basic,8.6354,4.4184,-29.352,0.9710249,0.2389783,0,8.657,4.4224,-29.352,use Theo = Yes Hit/basic,9.0814,5.3265,-29.352,0.4042207,-0.9146615,0,9.0761,5.3302,-29.352,use Theo = Yes Hit/basic,9.9153,5.2013,-29.352,-0.6550641,-0.7555733,0,9.9307,5.2203,-29.352,use Theo = Yes Endmeas/ Move/point,9.4625,4.8422,-29.3522 Circle3 =feat/circle,rect,in,least_sqr Theo/9.3996,4.6067,-29.76,0,0,1,1.5743 Actl/9.419,4.6213,-29.76,0,0,1,1.5754 Meas/circle,5,workplane Hit/basic,10.1866,4.6036,-29.76,-0.9999922,0.0039426,0,10.2064,4.6014,-29.76,use Theo = Yes Hit/basic,9.7917,3.9241,-29.76,-0.4980471,0.86715,0,9.7872,3.9249,-29.76,use Theo = Yes Hit/basic,8.6697,4.3118,-29.76,0.9272035,0.3745579,0,8.6913,4.3197,-29.76,use Theo = Yes Hit/basic,8.9327,5.2401,-29.76,0.5934024,-0.8049059,0,8.9297,5.2385,-29.76,use Theo = Yes Hit/basic,9.8794,5.2311,-29.76,-0.6092803,-0.7929549,0,9.893,5.2504,-29.76,use Theo = Yes Endmeas/ Move/point,9.4867,4.695,-29.7627 Move/point,9.4867,4.6951,-26.8188 Move/point,9.4867,8.7528,-25.1042 Point1 =feat/point,rect Theo/10.3996,4.6063,-28.9824,0,0,1 Actl/10.4192,4.6209,-28.9924,0,0,1 Constr/point,offset,circle1,1,0,0 Line1 =feat/line,rect,unbnd Theo/9.3996,4.6063,-28.9824,1,0,0 Actl/9.4192,4.6209,-28.9924,1,0,0 Constr/line,bf,2d,circle1,point1,, Cyl1 =feat/cylinder,rect,out,least_sqr Theo/9.3995,4.6065,-29.3712,-0.000013,0.0005203,-0.9999999,1.5743,0.7783 Actl/9.4191,4.6211,-29.3763,-0.0003899,0.0003382,-0.9999999,1.5759,0.7683 Constr/cylinder,bf,circle1,circle2,circle3,, A1 =alignment/start,recall:, List= Yes Alignment/level,zplus,plane1 Alignment/rotate,xplus,to,line1,about,zplus Alignment/trans,xaxis,cyl1 Alignment/trans,yaxis,cyl1 Alignment/trans,zaxis, Alignment/end Dim Loc1= Location Of Cylinder Cyl1 Units=in ,$ Graph=off Text=off Mult=1.00 Output=both Ax Nominal +tol -tol Meas Max Min Dev Outtol X 0.0000 0.0005 -0.0005 0.0000 0.7874 -0.7775 0.0000 0.0005 ----#---- Y 0.0000 0.0005 -0.0005 0.0000 0.7091 -0.7873 0.0000 0.0005 ----#---- Z -29.3692 0.0005 -0.0005 -29.3755 -28.9914 -29.7596 -0.0064 0.0069 <-------- D 1.5743 0.0005 -0.0005 1.5759 1.5771 1.5753 0.0016 0.0011 --------> H 0.7783 0.0005 -0.0005 0.7683 0.7683 0.7683 -0.0100 0.0105 <-------- End Of Dimension Loc1
I feel a lot better now that I've lost my mind.
Global Activ
PCDMIS CAD ++3.5 MR2
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What is it that you are measuring?
Is it a master of some sort or a actual part?
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Originally posted by cmmguy View PostWhat is it that you are measuring?
Is it a master of some sort or a actual part?
By the way, I didn't write the program. Someone else did. And we're using a completely different probe tip from before(but it calibrates fine).
But the program I created with the other tip (a 3by20) did the exact same thing.
There's a program for the ring gage. Did you need that too?I feel a lot better now that I've lost my mind.
Global Activ
PCDMIS CAD ++3.5 MR2
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Originally posted by operator1 View PostAnd yes, the alignment is done in Mode DCC.
When I want to repeat a bore gage measurement I set the machine to a ring gage. But, to get closer numbers you might want to consider measuring a Cylinder and setting algorythm to MAX Inscribe. A cylinder is not susceptible to alignment error like a circle is. Be mindful of shanking.
Also remember, a CMM ID (MAX Inscribe) is based on three points. Dial Bore Gage is based on two. CMM will come closer to an Intramic (3 points) but even there may be form error unless you are talking about a Calibrated Ring Gage. If you are measuring a Ring Gage your values should be MUCH closer than you reported. I would expect a few tenths.
Just some thought.Last edited by Wingman; 08-14-2007, 10:26 AM.Bill Jarrells
A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain
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Originally posted by Wingman View PostUnless something posted incorrectly or I am missing something your alignment is not done until after you measure your features.I feel a lot better now that I've lost my mind.
Global Activ
PCDMIS CAD ++3.5 MR2
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Originally posted by operator1 View PostThe part is called an Idler Pulley, and I'm checking the inside diameter of a bored hole.
By the way, I didn't write the program. Someone else did. And we're using a completely different probe tip from before(but it calibrates fine).
But the program I created with the other tip (a 3by20) did the exact same thing.
There's a program for the ring gage. Did you need that too?
When compared on a ring gage, then the variation you see is probing and machine caused.
Regarding the alignment, do that before remeasuring the bore, nto before the dimension only.Last edited by cmmguy; 08-14-2007, 10:28 AM.
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Always level any ring gage or master to the ID and not the face of the part. Do as the others have stated, make manual alignment, then DCC, then measure you bore where you want. Use prime numbers for your bore measurement, not really necessary but I have heard that the software calculates diameters better with prime numbers for the hits taken.
Just my .02.
DuaneXcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
Contura Calypso 5.4
Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.
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