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  1. Dean Watts

    Symmetric to Centerline note is given to below drawing attached, need to understand how manufacturer will punch the holes at what tolerance.

    Yes, I think so. It looks like datum feature A would be two planar surfaces at the outer ends, with a raised surface between them. The two outer holes could be "B" as a 2X pattern if they're the same diameter, or one could be B and the other C, for B-C. Then the three holes in the center and...
  2. Dean Watts

    Symmetric to Centerline note is given to below drawing attached, need to understand how manufacturer will punch the holes at what tolerance.

    I agree with 3DDave. If the holes on each end are the locating features, then I would choose them as datum features B and C, or as a pattern they could be datum feature B, if they have equal importance in located the part. It is likely that outer edges touch nothing but air. If so, then they...
  3. Dean Watts

    Symmetric to Centerline note is given to below drawing attached, need to understand how manufacturer will punch the holes at what tolerance.

    I'm late to the discussion, but will still add that I see no mention of the need for either the top or bottom planar surface, through which the holes are cut, to be specified as the primary datum feature, then the width and length could be the secondary and tertiary datum features. The two...
  4. Dean Watts

    Datum Modifier Effects - Planar Surface

    For 2018 Figure 7-37, when evaluating the profile on datum feature B, the part would not be oriented with respect to the LMB & MMB as it shown in the "Means this", it would be rotated CCW, as needed to satisfy the profile tolerance (which references only A), then the separate & independent...
  5. Dean Watts

    Unrelated Measured Minimum Material Envelope vs. Unrelated Measured Mating Envelope, Y14.45

    3DDave - In a perfect world Y14.5 would have incorporated the terminology we are discussing here that would make it consistent with its own intent in 2018. I will work towards ensuring this happens for the next release of Y14.5, and I hope all members, support group, visitors at meetings and...
  6. Dean Watts

    Unrelated Measured Minimum Material Envelope vs. Unrelated Measured Mating Envelope, Y14.45

    Good Morning Burunduk, Yes, there is a deliberate difference between Y14.5's median line and median plane material and the more complete and more specific information in Y14.45. The job for Y14 SC45 was to write a standard to provide guidelines for the data content associated with GD&T...
  7. Dean Watts

    Unrelated Measured Minimum Material Envelope vs. Unrelated Measured Mating Envelope, Y14.45

    Burunduk, If I am correctly understanding the point you are making, I think the issue is that we should have been more clear about the intent of the note applied to 3.23. The intent of the note is to point out that Y14.5 's definition of derived median plane does not acknowledge the LMC, so...
  8. Dean Watts

    Locating a spotface

    3DDave, Size tolerances and all tolerances at RFS do not use the related AME. We have a "hole" in the standard wrt relatively short features. It's a problem for hard gaging too, since position RFS, for instance applies to the axis that is defined by a thing (the UAME) that cannot be reliably...
  9. Dean Watts

    Locating a spotface

    Hi Burunduk, I think any feature of size that is short enough relative to its size, cannot reliably orient a UAME. This includes any 2D feature of size too, of course. I think it would be OK to apply a position tolerance to either the width on the circular shaft and the groove with fully...
  10. Dean Watts

    Locating a spotface

    Hi Kedu, The words just say "shall only be applied at regardless of feature size". Now that I've thought about this more, I wish that restriction specifically applied any time a tolerance is associated with a +DFT, -DFT or "Draft adds material" or "Draft reduces material". The resolved...
  11. Dean Watts

    Locating a spotface

    Hi Kedu, I knew Don well. I wish he was still with us so I could discuss that figure with him. I think it is wrong, but Y14.8 almost sort of supports it by including tolerances at MMC and LMC in the figures. I say almost sort of because Y14.8 doesn't explain how to deal with tolerances that...
  12. Dean Watts

    Locating a spotface

    Hi Kedu, Sorry for the lack of replies lately. Work is thankfully super busy for a few weeks. I think only RFS can be applied with <FF> +DFT oir -DFT (or draft adds/reduces material). I tried to explain why in an earlier comment. The 2D diameter or width has to be on the feature, not in the...
  13. Dean Watts

    Locating a spotface

    Hi Kedu, Yes, that is a figure that I have seen before. With a drafted feature that has a 2D size tolerance at one end only, I would not apply MMC or LMC. In fact, you bring up a good point. There should be a rule that prohibits modifying a tolerance at MMC or LMC if that tolerance is...
  14. Dean Watts

    Locating a spotface

    Hi Kedu, What Burunduk said [glasses] Dean www.validate-3d.com
  15. Dean Watts

    Regular Feature of Size Example - Parallel Opposed Line Elements and Circular Element

    This may not be directly helpful for the topic, but I thing the world would be a better place if MMB and LMB were expanded to all features. I think we could then get rid of the terms virtual condition, resultant condition, inner boundary, outer boundary, and worst case boundary. Simpler is...
  16. Dean Watts

    Locating a spotface

    Hi Burunduk, It could be done using profile of a surface if there was a method for specifying the MMB and LMB as separate values that comprise the profile tolerance zone (I also think the use of the terms MMB and LMB should be expanded beyond datum features, so we could then eliminate the terms...
  17. Dean Watts

    Locating a spotface

    Hi Burunduk, Yes, you have summarized my likely to be wishful thinking correctly. Over 50 years of history with the current approach makes no more tolerances modified at MMC or LMC and a separate way of specifying a single boundary that applies to a surfce a tough sell. Dean www.validate-3d.com
  18. Dean Watts

    Locating a spotface

    Hi Burunduk, I think those circular elements creating a feature of size are just as valid as the line elements at the ends of an elongated hole. I also would say that anything that can be measured with a CMM can be measured with hard gaging, but in some cases some special tooling may be needed...
  19. Dean Watts

    Locating a spotface

    Hi Kedu, Uh oh, yet another very good question [glasses]. Thankfully, that public review draft of Y14.8 that you might have read includes a restriction that the Full Feature modifier may only be applied for tolerances specified at RFS. The entire surface method vs. resolved geometry (axis...
  20. Dean Watts

    Regular Feature of Size Example - Parallel Opposed Line Elements and Circular Element

    tmillik, I'd just like to say that your questions are good and valid. I think Burunduk's responses address your questions well. The definition of feature of size should be both simplified and improved. It needs to a be a definition, rather than a list of examples. My personal opinion is...

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