Profile form and location without the location

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  • Profile form and location without the location

    got a difference of opinion with our engineers that has been going on for a couple weeks now. They are calling out form and tolerance of a ripple profile with a callout of .003”. Datum a is on the other side of the part(the base) instead of having basic dimensions to the ripple profile, the part has a total height tolerance zone of .040”.
    i have finally got them to agree that that doesn’t make sense. They don’t want to do a form only. They are concerned that the ripples will overlay but could be at an angle with pcsmis calling it good.
    i showed them that a composite profile would accomplish this but once again they don’t want to go that route. My question is “is there a way to make my z level (k I think) a datum but not call it back to the z location?” Basically a way to ensure ripple profile is parallel to z datum or perpendicular to z axis?

  • #2
    I think if you create an "Alignment"-Plane at the start of your program it should have your machineaxis as vector, then use that as a refdef later on? (the plane would be infinite, so location shouldnt be an issue if you only want to check if its parallell/perpendicular to you machineaxis Z/K.. might have to test around to see what vector it is that u need/want )


    • #3
      You can create an alignment that levels Z minus to the datum(assuming the vector is 0,0,-1), but don't set the origin. Then do a best fit Z translation only to the wavy top surface.
      Then do a profile Form and location of .003 of the wavy surface. It sounds like this is what they are after.
      PC-DMIS 2016.0 SP8



      • #4
        Sounds like they should be doing two things..

        1) Tolerance the location of the wavy surface as a standard bilateral ±0.020.
        2) Tolerance shape of the surface as "Profile of a Surface" and have PC DMIS measure "form only".

        They should give you some datum target points on the wavy surface that are basic back to your other datums. Using those coordinates for points in an iterative alignment, allow the machine to find the target points & create a plane through them to get your overall height. Then make an origin to that plane and then scan the surface or whatever to get your GD&T.


        • #5
          I was able to accomplish it 2 ways. One was with a composite profile and the other was with a customized drf which I told to disregard the z translate. I got the same measurement with both.
          Last edited by nitpicker; 09-12-2019, 05:30 AM.


          • #6
            Originally posted by nitpicker View Post
            i have finally got them to agree that that doesn’t make sense.
            Haha! You should look up ASME-Y14.5-2009 page 179


            • #7
              Hopefully this photo loaded. This explains my situation perfectly. How do I put this into pc dmis for form and location and get account for the from datum a height tolerance. Anything outside the .16 profile band is reported bad but drawing shows +/- .5?
              Attached Files


              • Mike Ruff
                Mike Ruff commented
                Editing a comment
                Does your drawing show Profile of a Line or Profile of a Surface? I don't think Profile of a Line is what you want

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