Tip Calibration Problems

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  • Tip Calibration Problems

    B&S Excel 7-10-7, PC-DMIS 3.7MR3, PH10mq, TP20

    This has happened yesterday and today. Haven't seen it before.

    Both days, we started the machine up. Then, we went to calibrate the tips used in a program. Upon completion of the calibration we get the error about the std dev. exceeding limits.

    Go to results file and the std. dev. is coming in around .0020 inches! So, yesterday, I tried a different probe and the same. Shut down, re-start and everything was fine (std. dev. .0001).

    Today, I get the same initially (.0020) shut down, re-start and .0020 still, different probe - .0020. Different module (tp20) - .0020.

    I checked to make sure the cal. sphere was defined properly - it was/is.

    I created a new probe file - .0020.

    Tried creating a new program - .0020.

    I tried answering yes and no at various times to the sphere having been moved - .0020.

    Suddenly, after switching back to original probe and original probe file - .0001. Now all seems to be good again.

    Anybody got any suggestions to try next time this happens?
    Last edited by #2#; 01-24-2007, 12:38 PM.

  • #2
    Delete the .0020 probe file & start over & see what happens.
    sigpic.....Its called golf because all the other 4 letter words were taken

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    • #3
      Clean the sphere & ruby ball real good? I had that problem once . Dimensions were way out of spec. Come to find out there was a piece of lint stuck on the ball.
      I used to be high on life but I built up a tolerance.

      Brown & Sharpe Global Advantage
      PCDMIS CAD++ v2011mr2
      PH10MQ/SP600M


      sigpic

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      • #4
        Originally posted by Underspec View Post
        Clean the sphere & ruby ball real good? I had that problem once . Dimensions were way out of spec. Come to find out there was a piece of lint stuck on the ball.
        Forgot to mention that I did that too.

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        • #5
          Check to see if you probe is tighten. I also had this happen, but I was using small probes and if my sphere was just straight enough the shank would hit. I was also having false probe hits until I got my machine worked on. I had to have all my belts, pulleys and bearing replaced on all 3 drives. That fixed all my false hits. Hope this helps.
          Dale
          v2011 MR1 CAD ++

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          • #6
            get a loop 10X...check for chips in the ruby or wear marks or aluminum build up
            sigpiccall me "Plum Crazy"....but you only go around once!

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            • #7
              What's the length of the stylus?

              If you have stylus extension - check that...I get that same thing if I use stylus longer than 60mm - also the longer the stylus the force on the module should match.
              PC-DMIS CAD++ 3.7 from 4.2 MR1

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              • #8
                Originally posted by WScmm View Post
                Check to see if you probe is tighten. I also had this happen, but I was using small probes and if my sphere was just straight enough the shank would hit. I was also having false probe hits until I got my machine worked on. I had to have all my belts, pulleys and bearing replaced on all 3 drives. That fixed all my false hits. Hope this helps.
                Good tip, I also forgot to mention that I did that.

                Originally posted by Mike N. View Post
                get a loop 10X...check for chips in the ruby or wear marks or aluminum build up
                Good tip, but that won't make a difference as it was giving the problem with any tip and any module attached to the tp20.

                Originally posted by JoeRZ View Post
                What's the length of the stylus?

                If you have stylus extension - check that...I get that same thing if I use stylus longer than 60mm - also the longer the stylus the force on the module should match.
                4x20mm tip w/ 30mm extension on a med. force tp20 module - but it did it with all probes I checked including a 2x20mm tip on a reg. force tp20 module.

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                • #9
                  It is just one of the enhancements to pc-dimis to keep us thinking.
                  sigpic

                  B&S Global 544
                  Using 3.7mr3


                  Peace
                  Greg


                  Nothin left ta dew but :) :) :) !

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                  • #10
                    Try increasing the number of probe hits on the artifact and set touch speed no more than 2%.

                    Then I dunno'...
                    PC-DMIS CAD++ 3.7 from 4.2 MR1

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                    • #11
                      Check that the TP20 contacts on both probe and fixed module are clean and free of chips. We had one where the lip around the fixed part was dented in towards the center. The probe would seem to seat but the dent was just enough to allow the whole thing to wobble in use.

                      Being cheap and flogged for budget excess- bent it out with needle nose pliers and back into repeatability.

                      Tom H

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                      • #12
                        I had very slight loosening of my tooling sphere in the holder once. That was very hard to spot. Tightened it back up and Bingo! Everything was Ok again. Just a thought.
                        sigpic
                        Cold Beer MMMmmmm........

                        Dell Precision T5400
                        Windows 7
                        B&S XCEL
                        WENZEL LH1512
                        PCDMIS 2011 MR1

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                        • #13
                          I'm having the same problem with a Mistral. I've added a "warm up cycle" to my calibration programs and they are now in spec. I reckon its a worn drive belt or pulley so I've an engineer coming in next month with enough spares to build a new CMM.
                          sigpic
                          To the Brave and the Faithful nothing is impossible

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                          • #14
                            Originally posted by than_357 View Post
                            Check that the TP20 contacts on both probe and fixed module are clean and free of chips. We had one where the lip around the fixed part was dented in towards the center. The probe would seem to seat but the dent was just enough to allow the whole thing to wobble in use.

                            Being cheap and flogged for budget excess- bent it out with needle nose pliers and back into repeatability.

                            Tom H
                            Good tip, I'll check that. I would guess it would be on the TP20 and not a problem with the module b/c it did it with more than one module. I will double check all of them though.

                            Originally posted by rerun_lives View Post
                            I had very slight loosening of my tooling sphere in the holder once. That was very hard to spot. Tightened it back up and Bingo! Everything was Ok again. Just a thought.
                            Another good suggestion. I don't think that is it due to the way my calibration sphere is constructed but I will check it anyway.

                            Thanks guys.

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                            • #15
                              Hey Goodluck,

                              Have you tried moving the artifact in a different location? there may be positioning problem in one of the machine axis in the vicinity of the artifact.

                              PC-DMIS CAD++ 3.7 from 4.2 MR1

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