Calibration

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  • Calibration

    After calibrating probe...best i could get on standard deviation was .0007....
    i am consistently off on my X by .0009mm on a 50mm master ring...am ok on Y .0001. Is there a way in 4.2 to put in any kind of probe offset to adjust for this on the X?? Thanks.
    Cubbie

  • #2
    Is that STD DEV in mm? IF so that fine anything under .01mm is acceptable.
    sigpic 1.61803399Δ
    ASSIMILATE INTERGRATE SYNTHESIZE

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    • #3
      The X .0009mm and Y .0001. dev you are referring to, what type of probe cal are you doing? Do you have sensors other than a TTP that you are trying to establish a probe offset to?
      sigpic 1.61803399Δ
      ASSIMILATE INTERGRATE SYNTHESIZE

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      • #4
        That is all in mm...i am using the user defined....24 hits...... 3 rows.....my problem is all my measurements on any part i do is off in the X by .001 or so...was just curious if there was a way to offset the X by .001 mm anywhere in pcdmis...i know it's not alot but the tolerances we have here are quite close.Thanks
        Cubbie

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        • #5
          Originally posted by DHoye View Post
          That is all in mm...i am using the user defined....24 hits...... 3 rows.....my problem is all my measurements on any part i do is off in the X by .001 or so...was just curious if there was a way to offset the X by .001 mm anywhere in pcdmis...i know it's not alot but the tolerances we have here are quite close.Thanks
          I don't get how ALL the measurements can be off in X by 0.001. Are you aligning before you take your measurements? No matter what your probe looks like (I HAVE used fish-hook shaped probes myself, ON PURPOSE!), if the probes are calibrated AND you align, everything should be in the correct relationship. How can all the measurements be off in X, but not the alignment?
          sigpic
          Originally posted by AndersI
          I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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          • #6
            Possibly be a probe module error if the error on your parts areall in one direction. You need to verify this with gage block stack or certified gage somehow.

            You could build a gage block stack with say a 4" with 2 other blocks and wring them so you would make a step gage (see pdf), set it on an angle or sine plate so you can rotate it without breaking the blocks apart, measure and create a center point between the 4" and the .5" then measure the outer point of the 4" block. Do this is all 4 axis and check the variation, you should see less than .0001"-.0002" between all 4 measurements. If it more than that try swapping modules and checking it again, if this does not show what you are seeing on your parts, then it is not the module and your CMM should be OK. There is something else wrong. Maybe a worn or damaged styli.

            Duane
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            Xcel & 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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            • #7
              post code?
              sigpic 1.61803399Δ
              ASSIMILATE INTERGRATE SYNTHESIZE

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              • #8
                It's odd how many times I see people asking here whether a poster is talking about inches or millimeters. If everyone would use the same conventions here when relating values less than one that the standard does, there would be no confusion.

                Example: 0.001 is mm, .001 is inch.

                ASME Y14.5M - 1994 section 1.6
                sigpic
                Global Advantage 12-22-10
                TESASTAR M SP25 4.3mr2

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                • #9
                  Originally posted by keego View Post
                  It's odd how many times I see people asking here whether a poster is talking about inches or millimeters. If everyone would use the same conventions here when relating values less than one that the standard does, there would be no confusion.

                  Example: 0.001 is mm, .001 is inch.

                  ASME Y14.5M - 1994 section 1.6
                  I go against convention on my drawings. Believe it or not I have been burned more than once by a monkey that misinterpreted no leading zero. So now even though all my drawings are English I use leading zeros.

                  It should be an organizational standard in my opinion, I see no reason ASME should dictate something that has nothing to do with interpretation or clarity.

                  OK, you can go back on topic now.
                  <internet bumper sticker goes here>

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                  • #10
                    OK.maybe i'm not explaining my self well enough!! I calibrate my probe.looks good....i then run a program to check a master ring XXX....it is within 0.0001 in the Y.... X is off 0.0010 (or around there). I spin master 90 degrees and run program again......same thing!! Now here's the next wierd thing, if i calibrate again sometimes the error of 0.001 is now in the Y....Somehow i think it is losing where it is at?? What i meant by ALL my measurements is i have run 10 different rings and they all ALWAYS show off either in the X or Y.by that 0.001....
                    Cubbie

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                    • #11
                      We definately need to see this program or more of a description of your alignment/setup. A ring is round, what do mean it is off in one axis?
                      <internet bumper sticker goes here>

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                      • #12
                        OK, still clear as mud.

                        WHAT is off in the 'x' axis? Are you talking about LOCATION or ROUNDNESS? WHen you say your ring gage is off in X, that really says nothing about the problem. It could be your alignment is messed up since we don't know WHAT is off in x. It could be that your machine is messed up.

                        When was the last time you had your machine calibrated? HOW was it calibrated? Ball-bar only? If so, then you will never have a leg to stand on when you try to assert that your machine is in calibration. Have you recentlly installed an upgrade of Pcdmis? Is it still using the table map? What controller do you have? Is the table map in the controller? Has your machine ever been certified to the 'step-gage' incremental/linear standard? Ball-bar alone will NEVER get your machine calibrated.
                        sigpic
                        Originally posted by AndersI
                        I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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                        • #13
                          Originally posted by craiger_ny View Post
                          So now even though all my drawings are English I use leading zeros.
                          You're kidding, right? This is the STANDARD!
                          sigpic
                          Global Advantage 12-22-10
                          TESASTAR M SP25 4.3mr2

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                          • #14
                            If you are off by 0.001 MM that is .00004 Inches. I would bet your machine is not that accurate. If you have a ttp your lobeing error alone is far more than that. If you are getting repeatbility of 0.001 MM that is pretty darn good.
                            Global FX 7-10-7
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                            Microval PFX
                            PC-DMIS 2012 mr1

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                            • #15
                              Originally posted by mhesse View Post
                              If you are off by 0.001 MM that is .00004 Inches. I would bet your machine is not that accurate. If you have a ttp your lobeing error alone is far more than that. If you are getting repeatbility of 0.001 MM that is pretty darn good.
                              I Agree
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                              B&S Global 544
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                              Greg


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