Icky Diameters

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  • Icky Diameters

    Ok, here's an interesting situation. I create a program that checks(amongst other things) a diameter. This diameter is supposed to be .7539 -.008. The tip calibrates fine. At the end of the program, the report says the diameter is over by at least anywhere between .003 and .0045. I check it with calipers and it measures (in metric) 19.15 or less--within tolerance. Can anyone see why it would do this?
    Last edited by operator1; 09-04-2007, 02:35 PM.
    I feel a lot better now that I've lost my mind.


    Global Activ
    PCDMIS CAD ++3.5 MR2

  • #2
    Originally posted by operator1 View Post
    Ok, here's an interesting situation. I create a program that checks(amongst other things) a diameter. This diameter is supposed to be .5739 -.008. The tip calibrates fine. At the end of the program, the report says the diameter is over by at least anywhere between .003 and .0045. I check it with calipers and it measures (in metric) 19.15 or less--within tolerance. Can anyone see why it would do this?

    Are you using least sqr or max insc, min circsc & another thing is your tolerance on the diameter is only 8 microns. I would not use a cmm for this check. My .02
    sigpic.....Its called golf because all the other 4 letter words were taken

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    • #3
      Originally posted by bw_bob View Post
      Are you using least sqr or max insc, min circsc & another thing is your tolerance on the diameter is only 8 microns. I would not use a cmm for this check. My .02
      NOOOOOOO, not 8 microns, 8 thousandths(of an inch). The .5739 is in inches, and so is the tolerance. When I check it with the calipers, the 19.15 is in mm.

      I take 2 rows of hits, create a cylinder, and check the diameter of the 2 circles and the cylinder. When I create cylinders, it's always least square. Maybe I should try some other setup option? What is max-inscribe and minimum circsc?
      I feel a lot better now that I've lost my mind.


      Global Activ
      PCDMIS CAD ++3.5 MR2

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      • #4
        19.15 -.2 in metric
        I feel a lot better now that I've lost my mind.


        Global Activ
        PCDMIS CAD ++3.5 MR2

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        • #5
          None of those numbers work out right. 19.15mm = .7539"
          19.15-.2 in metric = .7460"

          19.15 (metric) (.7539") -.2" = .5539"

          None of those options are even close to anything you posted for a size and tolerance.
          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
            My mistake......I saw metric on calipers & just assumed. Try the different kinds like suggested & see what results are.
            sigpic.....Its called golf because all the other 4 letter words were taken

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            • #7
              Didn't work. The circles themselves are oversized. I take hits and create the feature, but the features are reported oversized. Both circles on both rows.
              I feel a lot better now that I've lost my mind.


              Global Activ
              PCDMIS CAD ++3.5 MR2

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              • #8
                You still need to give us correct numbers, your metric manually readins DO NOT match what you say anything should be, 19.15mm = .7539" OR more than 3/4 of an inch, your callout says 0.5739 or LESS than 9/16 of an inch. THese is a big size issue here OR faty-finger syndrome.
                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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                • #9
                  You sure? When I use conversion calculators, I get .5739. When I divide the inches by 25.4, I get .5739.
                  And for the .2 tolerance, I get .0078, or .008 in inches.
                  I feel a lot better now that I've lost my mind.


                  Global Activ
                  PCDMIS CAD ++3.5 MR2

                  Comment


                  • #10
                    Are you checking plastic or sheet metal...Plastic is hard to check sometimes.
                    Make sure of your calibration
                    How many points are your using for your circles.
                    sigpic.....Its called golf because all the other 4 letter words were taken

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                    • #11
                      Originally posted by operator1 View Post
                      Ok, here's an interesting situation. I create a program that checks(amongst other things) a diameter. This diameter is supposed to be .5739 -.008. The tip calibrates fine. At the end of the program, the report says the diameter is over by at least anywhere between .003 and .0045. I check it with calipers and it measures (in metric) 19.15 or less--within tolerance. Can anyone see why it would do this?
                      19.15mm / 25.4 = .7539370...." or more than 3/4 of an inch. NOT even close to 0.5739"
                      sigpic
                      Originally posted by AndersI
                      I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

                      Comment


                      • #12
                        There is only a "minus" tolerance. The diameter can be no smaller than 18.95 and no bigger than 19.15.

                        In INCHES, the diameter can be no smaller than .5659 and no bigger than .5739
                        I feel a lot better now that I've lost my mind.


                        Global Activ
                        PCDMIS CAD ++3.5 MR2

                        Comment


                        • #13
                          Originally posted by operator1 View Post
                          There is only a "minus" tolerance. The diameter can be no smaller than 18.95 and no bigger than 19.15.

                          In INCHES, the diameter can be no smaller than .5659 and no bigger than .5739
                          19.05mm = 0.75" NOT 0.57"
                          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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                          • #14
                            SORRY. I'm having a dyslexic moment right now......it IS .7539. I typed it in backwards.
                            I a dum-dum. Sowwy
                            I feel a lot better now that I've lost my mind.


                            Global Activ
                            PCDMIS CAD ++3.5 MR2

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                            • #15
                              Yeah. It's supposed to be .7539 or .7459, but the CMM measures circle 1--the first row--as
                              .7575, circle 2--the second row--as .7569, and the cylinder--constructed at least sqr, max insc OR min circsc--measures over.

                              Sorry about that. I'm on another planet right now.
                              I feel a lot better now that I've lost my mind.


                              Global Activ
                              PCDMIS CAD ++3.5 MR2

                              Comment

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