Position of a scan

  • Filter
  • Time
  • Show
Clear All
new posts

  • Position of a scan

    Okay, me again with the same ridiculous print as last time. One side of this part has two slots of same size. Each has a position callout for the width within .01 of ABC, a length callout within .01 of ABC, and a profile callout within .01 of ABC. In all this makes 6 dimensional callouts to ABC across those 2 slots. To me it seems that a profile callout of the all around dimension within .01 is the same as each of the other two. So I decided to make a position call out of each slot to ABC and end up with a bonus on the slot even though the only bonus is a MMB on datum B. Now the machinist wants to know why. Any ideas? I've never positioned an analog scan before so not sure if I can even do generic features. The items are 20,21,and 22 Capturex.JPG

  • #2
    Over toleranced.

    The profile of a line to ABC controls the form and location of the slot, so the TP's are redundant.

    Either the slot should have TP, or the slot should have the all around profile. Not both.

    If you do TP, take off the MMC for slot size, since you aren't being given MMC.
    "This is my word... and as such is beyond contestation."


    • bigtallanddopey
      bigtallanddopey commented
      Editing a comment
      I would bet that they use them both for the same reasons that we do here. The production engineers complain that they cannot adjust the slot position from only the form tolerance so they include a TP tolerance too.

    • VinniUSMC
      VinniUSMC commented
      Editing a comment
      Ohh, I get it...

  • #3
    Thanks Vinni, that's my line of thinking too; much of this print is similarly overtoleranced, but I am obligated to report what the print states regardless of how ridiculous it is. My problem here is that doing a profile on the scans using Xact measure it automatically applies a bonus on the scan and I can't remove it. If I can, then how do I? Capturey.JPG


    • VinniUSMC
      VinniUSMC commented
      Editing a comment
      I wonder if that's just one of those "XactMeasure doesn't quite display right", deals? I know XactMeasure still has some issues. But, I haven't used it in the past 4.5 years, so I dunno if there's something else going on there.

    • Jim Poehler
      Jim Poehler commented
      Editing a comment
      Thanks Vinni, was wondering the same myself. I know Xact Measure still has a number of quirks. Appreciate the input.

  • #4
    Can some one please explain a bonus on a Datum and put it into a number value? I'm lost!

    Thank You.


    • VinniUSMC
      VinniUSMC commented
      Editing a comment
      There are plenty of threads here, and resources elsewhere, to get this question answered. Hijacking a thread is not the appropriate time or place. If you have a specific question, start a new thread. This is not the place to train GD&T.

    • william
      william commented
      Editing a comment

      These guys have a few videos on the subject. This is just one of them.

  • #5
    Jim remove the Diameter symbols from your callouts slots are widths not diameters!!
    (In Memory of my Loving wife, "Ronda" who I lost March 7, 2016. I love you baby.)
    They say "Nobody's Perfect." I must be Nobody.


    • #6
      Good catch Kirbster, however when I remove the diametrical symbol from the FCF I still have a .01 bonus on the scans. In discussion with my manager we are going to follow the advice of Vinni and go with line profile only and ignore the other two positional call outs as this is nothing but pure redundancy. Thanks much for your help guys. You would REALLY LOVE to see this complete print. It is a programmer's nightmare to say the least. Capturez.JPG


      • KIRBSTER269
        KIRBSTER269 commented
        Editing a comment
        didn't say it was gonna fix your bonus issue, why I didn't comment, no clue on how to help you with that matter. Just didn't want you to report it wrong.

      • Jim Poehler
        Jim Poehler commented
        Editing a comment
        Thanks, I always appreciate a second set of eyes as most of us do.

    • #7
      Hey Jim Poehler , I figured it out (sorry, not the bonus tolerance issue, but nice catch KIRBSTER269 on the diametrical tolerance symbol).

      Your slot can fail the surface profile control (by being too big, or too small) but still pass the TP control. Why they wouldn't just tolerance the slot as +/-.005 and make it a boundary TP is beyond me, but that is, i think, the "why".
      "This is my word... and as such is beyond contestation."


      • #8
        Profile of Line--(all around) for .250 Basic will give you a +-.005 per side so width of .250 can be .240-.260 form size control

        Location of slot --centerline axis has position tolerance to .230 Basic or .260 BASIC in a single axis as drawn must be in location +-.005 to the .230/.260 Basic

        Should report both in my opinion
        Last edited by Rich P; 01-11-2017, 06:38 AM.


        • #9
          Thanks to both Vinni and Rich for your thoughtful input. While I understand the defense of the separate call outs, would not the form and location as specified both serve the same purpose as it is defined from A (the flat surface of the disc), B (the OD of the disc, and C ( a clocking hole on the side) which would place the controls for each of the call outs at the exact center of the part? Maybe I'm missing something here in my understanding; if so please try to explain this to me.


          • VinniUSMC
            VinniUSMC commented
            Editing a comment
            Yes, surface profile would fully control the slot in form, location and orientation. It just won't tell you "where" the slot is. If it measures profile of .009, is that because the slot is big, small, off-center left, off-center right, off-center up, or off-center down?
            Last edited by VinniUSMC; 01-11-2017, 09:04 AM.

          • Rich P
            Rich P commented
            Editing a comment
            I think they are trying to give you larger size tolerance envelope with the profile (+-.010) while holding slot locations both slot axis each have TP .010 or ~ +-.005"

        Related Topics


        • blind829
          Slot Width/Length Bonus?
          by blind829
          I've attached a print and code of my program on v3.5MR2.

          First question is why is PC-Dmis adding both bonus tolerances, width & length,...
          03-23-2010, 06:53 AM
        • FMC.QC
          Position and Profile of Slot
          by FMC.QC
          Hello, I have a part similar to what is attached calling for a profile and position of a slot. My thought is to take planes on the 3 sides of the slot...
          01-18-2017, 06:02 AM
        • gordon
          MMC on Slot
          by gordon
          I have a square slot with a TP call out using MMC. The way the slot is called out MMC is granted from the slot length.
          When I dimension the TP,...
          12-19-2008, 10:05 AM
        • JamesMannes
          Slot true position
          by JamesMannes
          Can the friendly folks of the forum help me out?
          Can you give a concise explanation of the slot true position call out I am showing below? I have...
          05-22-2006, 02:33 PM
        • XANTHOFILE
          by XANTHOFILE
          Referring to the attached ,
          How do I get PC-Dmis to evaluate the "Boundary" condition for the two Positions for the slot [Items 14 and...
          06-10-2014, 01:46 PM