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  1. NormCrawford

    profile tolerance

    I say "cake shaped" because I don't know why everybody refers to a "wedge" as "pie shaped". I cut my cake with the same shape as I do my pie. It's a mood thing. Kind of like how people "feel" what they think they kind of meant when they put silly simple +/- dimensions on non-features of size...
  2. NormCrawford

    ANSI standard for leaders

    OK Jim, I am in if I can get invited to the Y14.41 table. But I forget now just who to contact directly. With regard to the leaders, I just want to summarize that there is room in a standard for "practices" and certainly meanings. That is to say; "know what a dot at the end of a leader means...
  3. NormCrawford

    ANSI standard for leaders

    Jim, I can understand the attempt to address the 3D environment. However, must of the "requirements" simply are not value added. For example, why is that we can not use an extension line for feature control frames or datum feature symbols? In 3D, using the common 2D extension line permits...
  4. NormCrawford

    ANSI standard for leaders

    Know that Y14.41 (3D annotation) has it's own leader requirements, which I am not particularly pleased about, but it does. Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  5. NormCrawford

    How to specify position of tapered pin?

    Both with profile Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  6. NormCrawford

    profile tolerance

    You could just have one BASIC dimension perpendicular to datum A and at either vertex of the slope. You do not need both given the BASIC angle. However, I would most likely use the vertex used for the BASIC angle just for clarity. But to be clear, there is nothing wrong with the way it is...
  7. NormCrawford

    Mating a Browning Bushing to a hub GD&T --- H, P, Q, & R Bushings

    The key way makes perfectly good mechanical sense to me if orientation (timing) of the mating part is needed or to carry shear loads for rotation (stopping rotation). I can't tell if this is a solid stationary bushing or rotating. In any case, the bushing (taper) is what actual mates to the...
  8. NormCrawford

    profile tolerance

    Yes. The default for Profile is equal bi-lateral with regard to the true (BASIC) profile. Unequal and unilateral can be specified for profile also. Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  9. NormCrawford

    Please help clarify datum shift vs bonus tolerance

    I don't disagree. If the design is such that there is so much clearance between the features of size that they "really" never control the "theoretical" degrees of freedom that the feature of size is theoretically capable of constraining, then it does not make sense to use that feature of size as...
  10. NormCrawford

    profile tolerance

    Don uses SolidWorks but I don't know that SW does the yellow shading or if that is done by post process artwork. The angle is controlled by a total width zone between two parallel planes that are 0.3mm apart perfectly located and oriented to the DRF by the BASIC dimensions. +/- cake shaped zones...
  11. NormCrawford

    How to specify position of tapered pin?

    Profile is usually the best way to control tapers/cones. One could use position of 0@mmc for the two end diameters for the "coaxial" control, which effectivly does define a virtual condition. But I go with profile. Sometimes the internal feature can be an issue and so using runout while stating...
  12. NormCrawford

    Mating a Browning Bushing to a hub GD&T --- H, P, Q, & R Bushings

    IF datum feature A is truly a "pilot feature" so be it. At first I was wondering why not have the taper itself as the datum feature. I would position the keyway with a parallel refinement. I question runout for datum feature B. Why not just use perpendicluarity? Is datum feature B rotating while...
  13. NormCrawford

    Please help clarify datum shift vs bonus tolerance

    Using an MMB (2009) or MMC (1994) modifier for a primary datum reference is very common and in reality often a good design practice if it allows the additional available functional shift (release of one or more degrees of freedom). It is a simple question to ask; "Does the primary datum feature...
  14. NormCrawford

    GD&T is it a philosophy

    A feature of size acting like a feature of size has an opposing feature of size into which it assembles too and/or can be defined as having a closed maximum or minimum material boundary. And of course, Happy Thanksgiving to all! Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  15. NormCrawford

    GD&T is it a philosophy

    Position does not control form. Yes, the unrelated actual mating envelope of the shaft should be checked. I don't know what 0 beyond MMC means or how it is stated. I assume the example is intended to be derive median line straightness and not surface straightness. Both form and size needs to...
  16. NormCrawford

    GD&T is it a philosophy

    The common reason that Rule#1 is not checked is because it is often envoked on features that are not actually functioning as features of size; typically because someone uses a +/- linear dimension where one really should not be used. So, during the measurement plan or some sort of risk...
  17. NormCrawford

    GD&T is it a philosophy

    Are we assuming from the sketch that the FOS portion of the feature is somewhat perfect? This is always a good point that you are making Evan. The size tolerance of .3 controls form for the feature FOS, but that FOS ends when there are no longer opposing elelments. So the question remains; What...
  18. NormCrawford

    GD&T is it a philosophy

    Evan, A hint: Size controls form. Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  19. NormCrawford

    GD&T is it a philosophy

    Roget that JP. Watch out now though. Although I would certainly use flatness, it is not a MUST. One could use profile there too without a datum reference. Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com
  20. NormCrawford

    GD&T doc

    Good point Evan on the friction thing with cones. But again, I deal with the reality of things. Lets just say that I am glad a shot glass works my way. :-) Norm Crawford GDTP-S Applied Geometrics, Inc. www.GDandT.com

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