how can i use different angle to measure one feature?

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  • how can i use different angle to measure one feature?

    How can I use different angle to measure one feature? For example, I need to measure a circle, but it need four different angles to measure it(a30b0/a30b90/a30b-90/a30b180). My software version is v4.1 release.

    Thanks in advance!
    The content mind is the greatest happiness a man can enjoy in the world.......

    SHEFFIELD CMM
    PCDMIS V3.7/V4.1/V4.2........

  • #2
    Gday ,have done this manually before fairly easy , just move probe to first angle(A30-B0) manually drive machine to desired location take first hit manually(dont hit done on your controller).Now input a move point or maybe two if you need to bring it out of the hole before it rotates(depends on hole dia)Select next probe angle(A30 B-90)take next hit manually and so on for next two hits.(you may need to input more move points) As long as you dont hit done on the controller the progarm will create one circle with the probe changes and move points included.Good luck
    the_cougar.JPG
    The Cougar

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    • #3
      Take single points and construct your diameter works in 3.5 anyway
      sigpic
      if you had soap on a rope it would be tied to yer ankle

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      • #4
        DO NOT use tip changes in the middle of a feature. Pcdmis ONLY uses the LAST tip used for probe comp. Use individual points, then construct the feature from those.
        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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        • #5
          Matt is correct. They didn't cover this well enough in the classes. I have measured both ways, and seen improved repeatability using features constructed from points when using multiple angles and / or a star probe.
          When in doubt, post code. A second set of eyes might see something you missed.
          sigpic

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          • #6
            I have to do this pretty often - rotate probe, go into the hole and take a point, move probe out of hole, change angles and repeat.....Just make sure all of the angles that you use, are calibrated

            Kind of like washing your hair........
            sigpic Life is not a journey to the grave with the intention of arriving safely, but rather a skid in broadside, totally worn, proclaiming WOW What a ride!

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            • #7
              Matt may be right not sure, i would debate this as i have used this method many times and so far hasnt given me any dramas. If probe comp changed (on or off) throughout 4 hits taken i would get dia error on holes. Holes are tied up to +/- 0.025 and measuring them has never been an issue.????
              the_cougar.JPG
              The Cougar

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              • #8
                Matt is correct. I have tested this and did see a slight difference. Less than .001 inch, but a difference that could decide rejecting a good part or accepting a bad part. If your tolerances are open, you may not have a problem. Barry, I am not sure if you meant +/- .025 mm or inches. I'd look closely at this if you are in mm. Also, if you are near the tolerance limits in inches.
                When in doubt, post code. A second set of eyes might see something you missed.
                sigpic

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                • #9
                  Thanks anyway! And I will try........... ^_^
                  The content mind is the greatest happiness a man can enjoy in the world.......

                  SHEFFIELD CMM
                  PCDMIS V3.7/V4.1/V4.2........

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                  • #10
                    Gday,
                    I may be missing something here and i am in mm John by the way. But if my circle is being measured using 4 hits and only one hit has probe comp on would i not get an error geater than .001"? Im from Aus so be gentle , cheers
                    the_cougar.JPG
                    The Cougar
                    Last edited by Barry Dawson; 06-28-2007, 11:47 PM.

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                    • #11
                      Originally posted by Barry Dawson View Post
                      Gday,
                      I may be missing something here and i am in mm John by the way. But if my circle is being measured using 4 hits and only one hit has probe comp on would i not get an error geater than .001"? Im from Aus so be gentle , cheers
                      [ATTACH]1505[/ATTACH]
                      The Cougar
                      No, not quite getting it.

                      Each tip in your probe file is calibrated. Each tip will have slightly different diameters from the calibration. When using multiple tips for a single feature, Pcdmis ONLY uses the diameter of the last tip used for comping the probe for ALL hits.
                      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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                      • #12
                        I felt that way at first, but did a quick study to prove it out. I frequently use a 5 way star. The balls on all the stylii are the same size. I changed one, both in the probe file and on the probe. If the probe comp is done for each tip, I should've gotten the same reading as the star with 5 equal size probes. I did not. I can't remember the differences, but it proved to me the compansation is done on the last tip only. Now, since you are using the same size ball, it won't be a huge error, but error does exist. We need to control all measurement variables that we are can.
                        When in doubt, post code. A second set of eyes might see something you missed.
                        sigpic

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                        • #13
                          Originally posted by John Kingston View Post
                          I felt that way at first, but did a quick study to prove it out. I frequently use a 5 way star. The balls on all the stylii are the same size. I changed one, both in the probe file and on the probe. If the probe comp is done for each tip, I should've gotten the same reading as the star with 5 equal size probes. I did not. I can't remember the differences, but it proved to me the compansation is done on the last tip only. Now, since you are using the same size ball, it won't be a huge error, but error does exist. We need to control all measurement variables that we are can.
                          OK, I just looked at one of my tip files. The Diameter range goes from 3.966 to 3.981 over 35 or so orientations. A spread of 6 microns. If I used ALL tips to measure a feature (or at least the two at the opposite ends of the spectrum) then I am looking at 3 microns compensation error (radial) due to incorrect tip, right? THen this gets added to the handful of microns that are inherent in the PH10M articulation changes, right?
                          So effectivly, with what I call a clean calibration, I can expect roughly 10 additional microns of error in a feature measured with multiple tip orientations (give or take a few for hit error which will be there either way), right?
                          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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                          • #14
                            Originally posted by Wingman View Post
                            The Diameter range goes from 3.966 to 3.981 over 35 or so orientations. A spread of 6 microns.
                            ???

                            15?

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                            • #15
                              Originally posted by Goodluck View Post
                              ???

                              15?
                              Fat fingers - LOL
                              3.976 - 3.981
                              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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