Plane to Plane

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  • Plane to Plane

    Hi,
    I was wondering if anyone could tell me how PC-DMIS views a plane to plane dimension. What my boss would like to know is when you level and set your origin to a plane and then ask for a locating dimension of a second plane, where on the plane is the dimension coming from. I.E. does it create a point equally spaced between the points used to create the plane? Because in theory the plane be projected infinitely and the farther away from the center of the plane you get it would be expected to have a worse deviation, thus the request. We are having an issue with a customer and would like to have this clarified if possible. Thank you in advance.

  • #2
    Originally posted by mrnoname View Post
    Hi,
    I was wondering if anyone could tell me how PC-DMIS views a plane to plane dimension. What my boss would like to know is when you level and set your origin to a plane and then ask for a locating dimension of a second plane, where on the plane is the dimension coming from. I.E. does it create a point equally spaced between the points used to create the plane? Because in theory the plane be projected infinitely and the farther away from the center of the plane you get it would be expected to have a worse deviation, thus the request. We are having an issue with a customer and would like to have this clarified if possible. Thank you in advance.
    It will come from the CENTROID which is a point 'equidistant' from all points making up the plane.
    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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    • #3
      My under standing is that it is calculated as a mid plane or average of the points taken. Measurements would be calculated from the center of the plane.......

      Is equidistant a real word Matt! usually I can tell right away but this one I'm not sure........
      ________________________
      DEA SCIROCCO-15-10-09
      TUTOR P -4.2 MR1-XP

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      • #4
        From dictionary.com:
        e·qui·dis·tant (ē'kwĭ-dĭs'tənt, ěk'wĭ-) Pronunciation Key
        adj. Equally distant.

        e'qui·dis'tance (-təns) n., e'qui·dis'tant·ly adv.


        The American Heritage® Dictionary of the English Language, Fourth Edition - Cite This Source
        Copyright © 2006 by Houghton Mifflin Company.
        Published by Houghton Mifflin Company. All rights reserved.
        When in doubt, post code. A second set of eyes might see something you missed.
        sigpic

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        • #5
          Originally posted by John Kingston View Post
          From dictionary.com:
          and your point??????
          Or are you just impressed with my knowledge of the ENGRISH RANGUAGE?
          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
            Originally posted by Matthew D. Hoedeman View Post
            and your point??????
            Or are you just impressed with my knowledge of the ENGRISH RANGUAGE?
            Well I was pointing out that it is a real word. Try to help a guy out and he gets all defensive.
            When in doubt, post code. A second set of eyes might see something you missed.
            sigpic

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            • #7
              Originally posted by John Kingston View Post
              Well I was pointing out that it is a real word. Try to help a guy out and he gets all defensive.
              Well, I sure didn't mean to knock your equilibrium out of equidistance with your soul, dude! Did you like my equivoque?
              sigpic
              Originally posted by AndersI
              I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

              Comment


              • #8
                Thanks to everyone who responded, that is what I assumed it was doing but I know what happens when you assume.

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                • #9
                  Originally posted by mrnoname View Post
                  Thanks to everyone who responded, that is what I assumed it was doing but I know what happens when you assume.
                  You do need to watch out for something... You can level and origin to EITHER ONE of those planes and get 2 different dimensions for the one you didn't level/origin to. This will be due to the planes NOT being 100% perfectly parallel and thus the centroid of the dimensioned one will be different, if ya follow me, since the centroids are not ever going to be perfectly 'above' one another.
                  sigpic
                  Originally posted by AndersI
                  I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

                  Comment


                  • #10
                    How silly of me not to believe Matt's Englais was spot on the centroid.

                    I am a troglodyte of epic proportions......a thousand salamis my leige......
                    ________________________
                    DEA SCIROCCO-15-10-09
                    TUTOR P -4.2 MR1-XP

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                    • #11
                      Originally posted by Matthew D. Hoedeman View Post
                      You do need to watch out for something... You can level and origin to EITHER ONE of those planes and get 2 different dimensions for the one you didn't level/origin to. This will be due to the planes NOT being 100% perfectly parallel and thus the centroid of the dimensioned one will be different, if ya follow me, since the centroids are not ever going to be perfectly 'above' one another.
                      I hear you there, one other thing the customer is doing is using a four point plane to level and origin to and then checking a three point plane which it seems to be influencing the results also.

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                      • #12
                        Originally posted by mrnoname View Post
                        I hear you there, one other thing the customer is doing is using a four point plane to level and origin to and then checking a three point plane which it seems to be influencing the results also.
                        Oh, tell them NEVER to use the minimum number of points for a multi-hit feature. EVERY 3-point plane will show perfect form, every 3-point circle will have perfect form, every 4-hit sphere will have perfect form. IF you know that the feature should be 'close' to perfect, adding 1 hit to the feature will tell you if it is AND tell you if something 'is wrong'. What if there was a grain of sand or grit or whatever right where one of the touches is? You'll never be able to tell since a minimum-hit feature will show 'perfect' form. For all my multi-hit features I always use at LEAST one more hit than minimum and have it report the 'form' (roundness, flatness, etc.) at least to the window so I can make sure all the hits were good.
                        sigpic
                        Originally posted by AndersI
                        I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

                        Comment


                        • #13
                          Originally posted by Matthew D. Hoedeman View Post
                          Oh, tell them NEVER to use the minimum number of points for a multi-hit feature. EVERY 3-point plane will show perfect form, every 3-point circle will have perfect form, every 4-hit sphere will have perfect form. IF you know that the feature should be 'close' to perfect, adding 1 hit to the feature will tell you if it is AND tell you if something 'is wrong'. What if there was a grain of sand or grit or whatever right where one of the touches is? You'll never be able to tell since a minimum-hit feature will show 'perfect' form. For all my multi-hit features I always use at LEAST one more hit than minimum and have it report the 'form' (roundness, flatness, etc.) at least to the window so I can make sure all the hits were good.
                          Thanks Matt I appreciate all your help/advice. Hopefully I can put all of this to good use I feel like the pickle in the middle here trying to convince both sides what is the better way of doing things.

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                          • #14
                            Originally posted by Matthew D. Hoedeman View Post
                            Oh, tell them NEVER to use the minimum number of points for a multi-hit feature. EVERY 3-point plane will show perfect form, every 3-point circle will have perfect form, every 4-hit sphere will have perfect form. IF you know that the feature should be 'close' to perfect, adding 1 hit to the feature will tell you if it is AND tell you if something 'is wrong'. What if there was a grain of sand or grit or whatever right where one of the touches is? You'll never be able to tell since a minimum-hit feature will show 'perfect' form. For all my multi-hit features I always use at LEAST one more hit than minimum and have it report the 'form' (roundness, flatness, etc.) at least to the window so I can make sure all the hits were good.
                            Perfect, yes and thank you Matt. This is something that has come up again and again with supposed learned people.

                            Even 4 hits on a complex or flat plate material like aluminum. For a larger surface is lacking fundamentals of Measurement analysis. If it's being bolted down and secured adequetly is one thing. If it's not a complete inspection is required. However many points is needed.

                            This really comes down to inspector purogitive but a serious attempt should be made especially if it's a GD&T callout. Stackups can kill an assembly operation and cause a lot of grief if they are all scrap.

                            Within the first few months of using CMM you should know about this.

                            This is fundamentals and a lot of dimensional disputes are settled in this humble way.

                            YOU NEVER HEAR FROM THEM AGAIN...........eh Matt?

                            Oh yeah........pickles mmmmmmmm...sour pickles in brine. yuuuuummmyah
                            Last edited by canada1_eh; 10-24-2008, 05:52 PM.
                            ________________________
                            DEA SCIROCCO-15-10-09
                            TUTOR P -4.2 MR1-XP

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