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  1. Garland23

    Perpendicularity to 3 datums

    You didn't describe the feature that the perp tolerance is applied to. But if it's a surface then yes, profile of a surface might be an alternate way to do things. But if it's a hole/pin or other "feature of size" then I wouldn't change the symbol to profile because that would change the...
  2. Garland23

    Datum Modifier Effects - Planar Surface

    Hi.... First of all, I think you're referring to just Fig. 4-31 and its sub-figures of 4-31(a), 4-31(b), and 4-31(c). They're all on page 73 of that 2009 edition. Regarding your main question, in that third example where they invoke MMB, yes one point of contact (minimum) is required. The...
  3. Garland23

    Hex hole as a datum feature

    Suppose we were dealing with a square peg/hole: If it had a similar dimension of .753 +/- xxx and the word SQUARE, would you also say that its definition is lacking? I wouldn't. (I know there's a square symbol, but I'm just posing this question to keep it analogous to the HEX question.)
  4. Garland23

    Hex hole as a datum feature

    Since the drawing clearly says "HEX," I think it's clear that the datum is intended to be created from the full six sides, not just the two flats being pointed to. In the ASME Y14.5 standard, Figure 7-3 shows two interesting examples at the bottom of that graphic. Although they are rounded, not...
  5. Garland23

    Maximum material condition on circular datum

    That's true for the boundary/simulator/counterpart; of course. But the initial question (highlighted in yellow in the first post) was whether the modifier affected DATUM B -- the "theoretical axis of the inner hole," to use the OP's phrasing. Thus, it's probably best to answer the question based...
  6. Garland23

    Maximum material condition on circular datum

    I'll be nitpicky -- that's not quite true. For a feature being toleranced with position at MMC (the four holes), that would be true. But a datum is always a theoretical plane, axis, point, or combo of those. With MMB, it just means that the theoretical axis is one that's derived from the feature...
  7. Garland23

    AVG and F symbol - fig 8-14/2018

    jassco, according to paragraph 8.4.3 of the 2018 standard, I think that the AVG notation already tosses R#1 out the window. So I'd still say that the F is not needed.
  8. Garland23

    AVG and F symbol - fig 8-14/2018

    I don't think the F is needed in Fig. 8-14, because the restraint note is clearly meant only for the circular runout check and nothing else.
  9. Garland23

    Is there a preferred true position standard?

    There is no way to say if a tolerance is tight or not, without understand the function and the mfg process juxtaposed to each other. (What is the purpose of the clip?) Why is .005 inch a tight tolerance? What if we were making something at a microscopic level? Then it would be a huge...
  10. Garland23

    Can Flatness have an associated Basic Dimension

    Perhaps the flatness callout is tagged to a surface that also happens to be a datum feature. Then, you could indeed locate a hole (position) from that "flatnessed" surface.
  11. Garland23

    Slot pattern Datums

    Attached is an example of a slot-type shape being used as a datum feature, from Fig. 7-3 of the ASME Y14.5 standard. However, since you are asking about two slots, you'd have to be careful not to overconstrain the degrees of freedom. Perhaps you could reference B and C with the "M" modifier...
  12. Garland23

    Perpendicularity callout with curved datum

    It sounds like the OP wants the axis of the hole to be perp to a theoretical plane that is tangent to the arc.
  13. Garland23

    Fuel Rail Supporting Mounts

    Check out Fig. 6-30 of the standard (I can post pic here, if you don't have access). There's a position tolerance on the threaded feature that relates back to datum C as its primary datum. Yet datum feature C is itself tied back to A and B via a runout tolerance. Fig. 7-22 (a) is another...
  14. Garland23

    Fuel Rail Supporting Mounts

    Hi -- it looks like you might be using ISO-style of dimensioning. I say that because of the first-angle projection symbol in the title block, and the fact the you have commas instead of decimal points (although neither of those are necessarily ISO things). So the first suggestion would be to...
  15. Garland23

    Datum callout question

    I don't mean to sound like a technophobe, but why not just do a pen/pencil sketch and post a scan or picture? That looks like a lot of work with the mouse or stylus! :)
  16. Garland23

    How cylindicity works?

    If you understand per-unit straightness (Fig. 8-5 from Y14.5), then cylindricity is somewhat similar: imagine a regular cylindricity zone, but instead of extending for the entire length of the feature, it is only for the designated length. The zone can slide along the feature, allowing some...
  17. Garland23

    Profil tolerance check (Unequally Disposed Tolerance)

    Doug, profile is not permitted to be modified with MMC (it's not a feature-of-size thing, but merely a surface or line). I think the terminology might be confusing. The go/no-go type of gauge that might work with profile isn't what we think of as a typical go/no-go; it's more of a template...
  18. Garland23

    GD&T question on position

    I suspect they intended it to be applied to one of the holes (the thru-hole or the counterbore).
  19. Garland23

    Profile tolerance unless otherwise specified - WRT Datums vs no datums

    I'll disagree a bit. Paragraph 3.68 defines true profile as requiring basic dims to define the profiled feature itself. It does not mention anything about the feature's relationship to any datums. If a DRF is imposed but the location dimension to the profiled feature is not basic, then it...
  20. Garland23

    Profile tolerance unless otherwise specified - WRT Datums vs no datums

    It's not arbitrary; one simply has to look at how the surface (well, line) is related to the datum. And in that case it's not a basic dimension, so we are to understand that it's doing the lower-level control of orientation. That's the specific indication that you're looking for. I'm sure that...

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