Funky TP Callout

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  • Funky TP Callout

    The print I have attached shows a few issues regarding GD&T.

    1. Is the Datum structure and the way it is to be used to align. I brought this one up the other day.

    2. The true position on the holes, doesn't seem to make a lot of sense to me regarding the way they are supposed to relate to the datums.

    I basically know what the customer wants, but, I would like to incorporate some logic into that my mind comprehends in the way of my CMM. For some reason, things just don't seem right to me. I am just fishing for some ideas.

    Thanks all
    Attached Files

  • #2
    The 2 slots called out to -A- only would be essentially perpendicularity, this has been discussed many times before.

    The part I'm confused with is that I see -C- datums called out, but no features referenced back to -C-. Also I see basic dimensions between the holes and the slots, but the only TP call out is to -A- and -B-, which wouldn't tolerance the basic dimensions from side to side.

    Either there's more to the print or I'd agree that that's some funky callouts.
    PC-DMIS 2016.0 SP8



    • #3
      1. I think I understand the datum structure. Datum A establishes the plane (3 points), datum B sets the orientation (2 points). That is not really a problem.
      2. The thing that I do not understand is the virtual condition on datum B in your call-out 11. I do not think that can be done.
      Also, call-out 3, although strictly taken correct, is also strange because it only ties it to A.

      Piece of advice: if you have the stomach to try it, the new dimensioning in V4.1 (XactMeasure dimensioning, as it is called in PC-DMIS V4.1) is sweet for problems like this. And after a lot of trial and error, I think it is pretty robust too!

      However, be careful with the VC on datum B. I think that is something that PC-DMIS does not do right. However, I am still debating this with them.

      PC-DMIS/NC 2010MR3; 15 December 2010; running on 18 machine tools.
      Romer Infinite; PC-DMIS 2010 MR3; 15 December 2010.


      • #4
        For the Datum Scheme, They should have used target -A-'s instead of the Datum -B- call out, The two Datums -C-'s are really, the hole is Datum -B- and the slot is Datum -C- So level to -A- & -B-, Origin on hole and Rotate to slot.

        And yes, the TP is all screwed up too. Who did this one print, was this some High School project?
        sigpicSummer Time. Gotta Love it!


        • #5
          Thanks for the replies.

          I figured out for the most part concerning the alignment, however, I didn't level on both A & B. Paul, can you splain that one in a little more detail?

          I basically leveled A, rotated slot, used B to let PC-DMIS know hole was relative to this surface, then I set the origin (x, y, and z) on the hole. I played around with best fits and such, and even iterative, but stuff didn't make sense still when trying to use both surfaces to level.

          I would appreciate any further explanation on that one. I have attached a shot of my current alignment.

          I am going to do the TP's against the datum scheme and just get r done, someone understood this, there is a rather nice gage built for it.
          Attached Files
          Last edited by dccfreak; 09-21-2006, 01:17 PM.


          • #6
            I disagree with your current alignment. I would use an iteritive alignment I would take points on -A- and -B- and level to them. Rotate from -C- hole to -C- slot, and make origin to the -C- hole. And leave it in body position and do my Tolerancing from there. If you do not use Datum -B- as part of your leveling you are not going to get the correct results.

            Why don't you get a hold of them and have them explain their print.
            Last edited by Paul Sarrach; 09-21-2006, 01:55 PM.
            sigpicSummer Time. Gotta Love it!


            • #7
              2 datum -c- (WTF?)

              Max material modifier on -B- , a surface (another WTF?)


              sigpicHave a homebrew


              • #8
                -B- is not a FOS. -C- is shown 2wice (hole and slot) and a datum symbol is used on both. That is a no-no. Datum targets should be used to define the features, and the symbol ( whish is identifiing the datum axis) should be related to 1 feature only. Although it can be shown as many times as nec. to provide clarity.
                Also, the boundary position is incorrect.
                So, yes - both of those FCF are either incomplete, or incorrect - whatever way you want to look at it.
                RFS Means Really Fussy Stuff

                When all you have is a hammer - everything looks like a nail....


                • #9
                  My alignment is simulating the position the gage was built in. That is why I did it like that cause that made sense to me.

                  Iterative was my first choice, but, if I leave it in body axis I can't dimension the part in accordance with the print. That is why I was trying to figure out what I could use as my final, and thus why I tried to align it like the gage.

                  I am pretty much on my own where trying to get information from the customer is concerned. It takes like 3 or 4 weeks to get your request far enough into the organization for anyone that cares to give you an answer. I need to have this done by tomorrow. I don't even have hole coordinates for body axis, usually I have them.

                  Wish I had a laser, that would be cool......


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