ASME Y14.5-2018 errata
ASME Y14.5-2018 errata
(OP)
In 5.3.2:
(b) Where bilateral tolerancing is used, both the plus and minus values and the dimension value of .500 shall have the same number of decimal places, using zeros where necessary.
I'm guessing that inch bilateral tolerancing applies to other dimension values than .500.
Also, when padding the number of digits, was it thought to be unclear what digit would be used? It's like finding training wheels on both the front and rear of a child's bicycle.
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An interesting difference from '2009 to '2018 is the exchange of the rather uniform use of the word "where" to indicate a use on a drawing to a spotty use of the word "when." I don't see a pattern to this. It suggests that the 2018 version was particularly rushed in some cleanup effort. If only there was a Github for it with comments on the commits to sort out why.
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Also, for a document that is literally trying to define "shall" for the application of various techniques, the hundreds of new uses of "shall" in the text seems unnecessary. The usage of "shall" more than doubled from the old version to the newer. It's a shall of it's former self.
https://www.plainlanguage.gov/guidelines/conversat...
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(b) Where bilateral tolerancing is used, both the plus and minus values and the dimension value of .500 shall have the same number of decimal places, using zeros where necessary.
I'm guessing that inch bilateral tolerancing applies to other dimension values than .500.
Also, when padding the number of digits, was it thought to be unclear what digit would be used? It's like finding training wheels on both the front and rear of a child's bicycle.
---
An interesting difference from '2009 to '2018 is the exchange of the rather uniform use of the word "where" to indicate a use on a drawing to a spotty use of the word "when." I don't see a pattern to this. It suggests that the 2018 version was particularly rushed in some cleanup effort. If only there was a Github for it with comments on the commits to sort out why.
---
Also, for a document that is literally trying to define "shall" for the application of various techniques, the hundreds of new uses of "shall" in the text seems unnecessary. The usage of "shall" more than doubled from the old version to the newer. It's a shall of it's former self.
https://www.plainlanguage.gov/guidelines/conversat...
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RE: ASME Y14.5-2018 errata
When you are on this Forum, where you find a simultaneous requirement of some humor, you shall constrain yourself from drawing upon puns.
RE: ASME Y14.5-2018 errata
This is identified only in the Uniform Tolerance Zone section. I would think that specifying the direction of the allowed variation would apply to all profile tolerance cases.
RE: ASME Y14.5-2018 errata
So, just one letter and it must be in a square or rectangular frame. OK. All squares are rectangles and there is no tolerance given for how much a possible square might not be an exact square; it's not clear why there is any point in mentioning using a square - a rectangle that happens to be a square should be acceptable as a rectangle.
Then comes the contradiction - or with nothing initially saying that there is an alternative means of creating a datum feature symbol:
It's not "The means".
A single uppercase letter is one of two means of creating that symbol.
It's "A means".
RE: ASME Y14.5-2018 errata
6.3.2.2
" placed on an indicated partial datum feature. "
Is it a datum feature or not a datum feature? It doesn't seem as if a datum feature can be "partial."
At least the standard agrees with me -
Neglecting that a surface cannot be partial; they can be partitioned or one can limit the scope to a portion of a surface - a surface is a surface is a surface - sure, one can partially clean or paint a surface or partially machine one surface to create another one, but the surface itself is still itself, identifiable as a surface unless it is removed.
Seems like a good way to ruin test scores, in 5-10 years when the test is updated, to ask about partial datum features and, no matter the answer, score it wrong, as there is a contradiction built into the text.
Pack in that "a partial surface in note form or by a datum target" and ask if "chain lines are used to indicate....?" and fail those who say "Yes" to that as well, as datum targets are also partial datum features. Or not.
To test takers - if you miss passing by one point and this is on the test - this may be why.
RE: ASME Y14.5-2018 errata
Doesn't "A datum target symbol is a circle divided horizontally into halves." cover this more concisely?
It's in the Datum Target Symbol section - There is no need to refer to "symbolic means of indicating." If the reader doesn't know what symbols are for then I think that this won't help them. Maybe lead off with what a datum target is so the reader knows why they might use a symbol?? More thinking - this isn't a datum target symbol, this is a datum target identifier symbol - the point, line, or area is the actual datum target; this just has a unique identifier for the symbol itself with maybe some auxiliary info. Too bad. That ship sailed long ago.
Maybe do it in one shot:
"A datum target symbol is a circle divided by a horizontal line* into halves where (when?) the lower half contains an uppercase** letter identifying the associated datum, followed by the target number assigned sequentially starting with 1 for each datum and the upper half is used, as required, for the size and shape of the area (true geometric counterpart) or is otherwise left blank."
I'm not even going to deal much with Fig 7-50. The note says the part is to be restrained but the feature control frames say the only ones that make sense to restrain are not restrained. Or does it mean that the A targets are restrained (because (F) isn't next to the "A") and if the part isn't restrained at the D targets then maybe the D targets are defined in the model so that restraint on the A targets will force the part into contact with the D targets and that fact is invisible in this view? Doesn't a restraint requirement specify how much restraining force is required/allowed? I think a general note about that makes more sense. If that isn't part of the general note then maybe that should not be the general note.
*Not halved using dashes, not by removing segments of the perimeter of the circle, not by a squiggle, not with a yin-yang like division.
**It was important when identifying datums in datum feature symbols to mention uppercase; should be consistent.
RE: ASME Y14.5-2018 errata
The paragraph about "common datum features" says the MMB/LMB modifier is applied following each reference letter. It wouldn't be needed if the modifier was meant to apply to both parts of the common reference when specified after the second one. So by an extension of a principle the same goes for the "F" modifier. The definition in 7.12 should have been more general. Each letter is treated separately, then the "A" targets are restrained. The D target areas are referenced in free state, and they don't need to be forced into contact with their target simulators. All "A" and "D" target areas act to constrain the same degrees of freedom, so it is an "oversconstrain" by intent. In that case the unrestrained (free state) datum targets are not required to be in contact with the part, and may not be, depending on the particular as-produced part geometry.
RE: ASME Y14.5-2018 errata
Glad that you agree exactly with what I thought the illustrator was trying to express even though it would have cost literally nothing for the committee to write that out explicitly. It's a puzzle though that sometimes they are explicit and you think they are wrong.
The magic words - "extension of a principle" cover a multitude of omissions and errors don't they?
RE: ASME Y14.5-2018 errata
What I find unclear is how restraints are supposed to be applied to the part against MMB datum feature simulator pins, as shown in figures 7-51 and 7-52, datum reference "B(M)".
RE: ASME Y14.5-2018 errata
Anyway 7.20.4.5
RE: ASME Y14.5-2018 errata
True, but the note fig. 7-52 explicitly states that that restraints are applied on both datum feature simulators "A" and "B". It is not even the barely going through the motions "UNLESS OTHERWISE SPECIFIED" in fig. 7-51 where the "otherwise specified" is only in 7.20.4.5 and not in the figure representing the drawing.
It is not defined how datum target areas need to be depicted on an edge view anywhere outside of fig. 7-51, and it is apparently the same as a datum target point and datum target line. While it is intuitive why a point and a line would look the same in an edge view, a chain line would make more sense for an area.
RE: ASME Y14.5-2018 errata
Perhaps I'm just tired but I don't see a large problem with 7-52 that isn't swept under the "figures are incomplete" rug. In the spirit of things it's a surprise it's not "THE PART SHALL BE RESTRAINED ..." for inspection of noted features.
It is interesting that Figure 7-27 is not referenced as a restrained condition example when it goes into such detail. That seems like a clear oversight.
RE: ASME Y14.5-2018 errata
RE: ASME Y14.5-2018 errata
RE: ASME Y14.5-2018 errata
I agree, but datum feature B is not restrained in any stage of the process, is it?
Can we justify the note in fig. 7-52?
RE: ASME Y14.5-2018 errata
It's true that the part isn't muscled against those 4 holes. When I teach about restraint notes, I mention that the note should spell out the exact parameters, such as specific location of restraint, the amount of force/pressure, and even the sequence of clamping (if multiple clamp locations). So I agree that the note in Fig. 7-52 isn't very good.