GD&T Profile & TP Print Question

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  • GD&T Profile & TP Print Question

    On this print, there are a couple questrions I have. First off, thay have Datum B called out 2 different times, one as an outside Dia. & the other as the entire profile of the part. The profile callout is .060 to Datum A. Wouldnt this just control the perpendicularity of the edge of the part to A. The last question is the TP callout of the holes. They have a TP of 0 called. Im thinking they want to use the bonus tolerance to control the position. Is this a standered accepted practice?

    The big question is how to check it? Do I best fit the profile & holes to the nominal & dimension from there?

    10-27-2010 Print.jpg

  • #2
    I can't read the print. But a zero position tolerance is used with a material modifier, MMC or LMC. In other words, if MMC is used and the hole is the smallest Ø allowed, it MUST be in it's True Position, called out by the basics. No deviation. As the hole gets larger, the tolerance grows.
    Global Advantage 12-22-10
    TESASTAR M SP25 4.3mr2


    • #3
      Gotcha, thats kind of what I thought. Now I just have to figure out this profile issue.


      • #4
        Print is really hard to read, very washed out, but it appears to me, that there is an all-around circle on the leader line from the surface profile control frame to the part. That would mean that the profile of the surface is controlling perpindicularity to A, but they are also using it to control the form of the 56.5° (?) angled faces on the ends of the part, the 45° chamfers from those faces to the outer radius, the inside radius. I would guess that the engineer was saying that it is -B- because the leader is pointing at the outside radius, also labled -B-, but that's a guess. Unless you have some other control boxes for the basic angles and the chamfer length and inside radius, that profile is controlling them also... imo.


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