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  • D-e

    Good afternoon,

    We are trying to learn Xact reporting. We have a feature control frame with datums in in like this.... D-E. See attachment. I tried typing it in just like that, but it switches the X, and Y, axis. Can this be done correctly?

    Thanks.
    Attached Files

  • #2
    What version of DMIS are you using?
    Remembering my beautiful wife Taz who's life was lost on 6-13-2020. I love you and I miss you.

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    • #3
      Is it like 2 ends of a shaft or something similar ? Construct a line between the features and use that as the DATUM D-E. You would need to use a variable for the size. What if both ends are different sizes ? How would you assign a MMB to that ....... This is just an example and there are so many possbilities with limited information.

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      • #4
        Are the vectors of D and E in the same direction? What are D and E? Cylinders or Circles?

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        • #5
          Depending on your version, you should use either XactMeasure (https://docs.hexagonmi.com/pcdmis/20...ums&rhsyns=%20) or the geometric tolerance command (https://docs.hexagonmi.com/pcdmis/20...tum&rhsyns=%20).
          Neil Challinor
          PC-DMIS Product Owner

          T: +44 870 446 2667 (Hexagon UK office)
          E: [email protected]

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          • #6
            Hmm Yes,

            Should have provided more information. Didn't think about what you guys would have to work with. D and E are inside diameter cylinders. They are parallel with each other, and 180 mm apart. They are not colinear. On my machine the vector of D is Z-, and the vector of E is Z+. D was, of necessity, constructed from points BFRE. E was taken as an auto feature, and the "bottom" hits were taken first, so the vector is Z+. Perhaps I should flip the D vector? E is 180 mm in the Y- direction from D. D is the larger of the two, and for most of the X Y dimensions on this part it is the origin. What we are measuring to D-E is the location of the center of a flat root spline tooth cut into the I. D. of D. On the print, the center of that tooth is on a line passing through D and E. If I were to be measuring this using an alignment, I would level to D, Rotate to E, and fix the origin of X, and Y, at the center of D. The Z origin would be a plane on the "bottom" or Z- side of the part. We are using the 2019 version of PCDMIS. Lol, we have purchased the 2020 version, but this dummy can't seem to get it changed. But that's another story.

            Thanks for your help.

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            • #7
              Originally posted by Flintstone View Post
              Hmm Yes,

              Should have provided more information. Didn't think about what you guys would have to work with. D and E are inside diameter cylinders. They are parallel with each other, and 180 mm apart. They are not colinear. On my machine the vector of D is Z-, and the vector of E is Z+. D was, of necessity, constructed from points BFRE. E was taken as an auto feature, and the "bottom" hits were taken first, so the vector is Z+. Perhaps I should flip the D vector? E is 180 mm in the Y- direction from D. D is the larger of the two, and for most of the X Y dimensions on this part it is the origin. What we are measuring to D-E is the location of the center of a flat root spline tooth cut into the I. D. of D. On the print, the center of that tooth is on a line passing through D and E. If I were to be measuring this using an alignment, I would level to D, Rotate to E, and fix the origin of X, and Y, at the center of D. The Z origin would be a plane on the "bottom" or Z- side of the part. We are using the 2019 version of PCDMIS. Lol, we have purchased the 2020 version, but this dummy can't seem to get it changed. But that's another story.

              Thanks for your help.
              The "-" in "D-E" means "D THRU E". That being said, in order for them to be "thru" one another, D and E must be coaxial. In your situation, they're not, so I would politely discuss with design authority that this is incorrect GD&T & would request further clarification of what they want.

              From experience, they could/most likely mean..

              |TP| Ø| 0.0029|D|E(M)
              In which case you'd...
              1) Use XACT to build feature control frame, voila!
              2) If using legacy...Level to cylinder -D-, rotate to a line that is from -D- to -E-, make -D- X and Y origin, set Z wherever you want, check the TP while recalling that origin

              If -D- is a short cylinder, they (design authority) might want to add a planar feature to the feature control frame as the primary. Something like |TP| Ø| 0.0029|A|D|E(M). This would drive you to Level through -A-, rotate to line that is from -D- to -E-, -D- is X&Y origin and -A- is -Z- origin.

              Leveling through a short cylinder (not the best but is required for specific proposes like on some of my parts) can yield funky results. The smaller the cylinder, the worse the form error will get exacerbated through the alignment. I have a part that has two cylinders that are each only 0.250" long and are 13" apart from one another that have to be concentric w/in 0.0015 (talk about a pain in the a$s!). It sucks but this is what my customer wants because there are going to be some high precision bearings press fit into those IDs.

              My company makes precision components that spin inside of aircraft engines, I deal with these types of callouts a lot (A-B structures, concentricity, coaxiality, total runout, runout, etc..).

              Hope this helped!
              Last edited by DAN_M; 01-22-2021, 09:59 AM.
              SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

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              • #8
                We tried this this morning by constructing a line between D and E, and giving it the Datum Definition of LE. Then we built the FCF as D-LE. The vectors didn't flip this time, but the report showed zero error. We know that isn't the case.

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                • #9
                  Thanks Dan, I'll do that.

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