Profile Of Flat Surface, Feature Set or Plane?

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  • Profile Of Flat Surface, Feature Set or Plane?

    What method do most of you guys use when doing a profile of a flat surface.

    Would taking a group of vector points and creating a plane for profile or making them a feature set be the correct method?

    I've tried both and they produce different measurements as well as different max and min measurements, even though the very same points were used to create them both.

    Any reason as to why?

  • #2
    Originally posted by Scott C. View Post
    What method do most of you guys use when doing a profile of a flat surface.

    Would taking a group of vector points and creating a plane for profile or making them a feature set be the correct method?

    I've tried both and they produce different measurements as well as different max and min measurements, even though the very same points were used to create them both.

    Any reason as to why?
    Flatness of a plane is FREE-FORM (form only) while PROFILE was probably done as FORM AND LOCATION. Use which ever your print calls out, if it says flatness, do flatness, if is say PROFILE, use profile.
    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
      you could do a feature set and dimension profile or dimension individual vector points using the deviation along the nominal vector T value or both.

      i would recomend the T dimension on indiviual points that way you can see the numbers for each point.
      sigpic

      I like to use slow circular moves. It builds tension and heightens the sensation. -Ironhoe

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      • #4
        You should be getting the same MAX and MIN deviations from a plane and a set because they are from the same features. Are you sure you didn't miss one point in the construction of the set? Do you have use datums turned on in one or the other? Are you checking profile "form only"?
        sigpic GDTPS - 0584

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        • #5
          Originally posted by inspector212 View Post
          You should be getting the same MAX and MIN deviations from a plane and a set because they are from the same features. Are you sure you didn't miss one point in the construction of the set? Do you have use datums turned on in one or the other? Are you checking profile "form only"?
          IF he makes a plane, then does PROFILE FORM & LOC, he WILL get different values than flatness since flatness would match FORM ONLY for the profile of the plane, like I said, he has to use what the print calls for, if it say FLATNESS, he has to use flatness, if it is PROFILE to ABC, then it is PROFILE FORM & LOC, if it is profile with NO datums, then it is FORM ONLY. He has to use what the print calls for.
          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
            it also depends on how you want to present the data.

            is it a customer that maybe you dont want to give too much information and just want to show the profile spec or is it for guys in the shop that are trying to develop something and need to know where each point is?
            sigpic

            I like to use slow circular moves. It builds tension and heightens the sensation. -Ironhoe

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            • #7
              Originally posted by winston View Post
              you could do a feature set and dimension profile or dimension individual vector points using the deviation along the nominal vector T value or both.

              i would recomend the T dimension on indiviual points that way you can see the numbers for each point.
              Do you have Cad?
              When using feature set you can also report "graphical analysis" good representation of the actual condition vs. the nominals.
              It depends on the amount of poinst needed (scan?), and whether you prefer no to report too many T dimensions.

              My .o2
              sigpicIt's corona time!
              737 Xcel Cad++ v2009MR1....SE HABLA ESPAÑOL

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              • #8
                Guys, I need to clarify this more.

                I am constructing a feature set as well as a plane from the very same vector points, yet when dimensioning profile (form only) for both of the features, the measurements are 0.010 to 0.060 microns different and the max and min points for each feature are different and occuring at different locations on the surface.

                Any thoughts on this?

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                • #9
                  are you using CAD?
                  Automettech - Automated Metrology Technology

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                  • #10
                    Originally posted by Scott C. View Post
                    Guys, I need to clarify this more.

                    I am constructing a feature set as well as a plane from the very same vector points, yet when dimensioning profile (form only) for both of the features, the measurements are 0.010 to 0.060 microns different and the max and min points for each feature are different and occuring at different locations on the surface.

                    Any thoughts on this?
                    Well, a SET is NOT the same as a plane. A plane can be constructed using a couple different methods, have you tried each one? Are you doing a BEST-FIT or a best-fit re-comp? A best-fit recomp will change all the probe comp's for all the points in the plane, to whatever the vector of the constructed plane it, but just for the construction of the plane, the set will not alter ANY thing it uses.

                    IF you do a BEST-FIT (no re-comp), then you SHOULD get the same PROFILE ~ FORM ONLY and FLATNESS values. The min/max MAY be different because of the way a plane in constructed and MAY be different points, but the TOTAL should be the same.

                    HOWEVER, depending on WHAT version you are using, what you are seeing might NOT be what you think you are seeing. Some versions, for PROFILE, will give you a value equal to the MAX -MIN values, some will DOUBLE the worst value, V4+ will give you the choice of which way (not sure where you select, but have heard that it is there). This profile method MAY be FORM & LOCATION and not FORM ONLY, but I do not know.
                    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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                    • #11
                      Originally posted by Matthew D. Hoedeman View Post
                      IF he makes a plane, then does PROFILE FORM & LOC, he WILL get different values than flatness since flatness would match FORM ONLY for the profile of the plane, like I said, he has to use what the print calls for, if it say FLATNESS, he has to use flatness, if it is PROFILE to ABC, then it is PROFILE FORM & LOC, if it is profile with NO datums, then it is FORM ONLY. He has to use what the print calls for.
                      ok
                      Last edited by inspector212; 07-31-2008, 12:54 PM.
                      sigpic GDTPS - 0584

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                      • #12
                        Originally posted by winston View Post
                        you could do a feature set and dimension profile or dimension individual vector points using the deviation along the nominal vector T value or both.

                        i would recomend the T dimension on indiviual points that way you can see the numbers for each point.
                        Guys,
                        I don't use T dimension often, so bear with me.
                        How do you determine T tolerance?

                        Let's say part print calls out: Profile/A/B/C 0.005
                        What tolerance for T?
                        sigpicIt's corona time!
                        737 Xcel Cad++ v2009MR1....SE HABLA ESPAÑOL

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                        • #13
                          Originally posted by Roberto View Post
                          Guys,
                          I don't use T dimension often, so bear with me.
                          How do you determine T tolerance?

                          Let's say part print calls out: Profile/A/B/C 0.005
                          What tolerance for T?
                          +/- .5T for bilateral profile.
                          Saving the world, one bad part at a time.

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                          • #14
                            Depends on the standard used (ASME/ISO)?
                            PC-DMIS CAD++ 2o19 R1 SP6

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