Trick questions 1

[3DDave]

Per the 2009 version:

Is a titleblock tolerance a direct tolerance?
Are there any indirect tolerances?

 

[Burunduk]

Bssic dimensions have no tolerance. It's the point of them being basic. There is no variation at all allowed to basic dimensions.

Well at least per the 2009 version of the standard, your statement is controversial, as Fundamental Rule (a) states that:

"Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum, or stock (commercial stock size). The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions), indicated by a general note, or located in a supplementary block of the drawing format.

I take that to mean that in the case of basic dimensions, the tolerance does not apply directly to the dimension but it applies to the location, orientation or form of the feature which the basic dimension defines.

"Direct tolerancing" is when tolerances are applied directly to either dimensions or features. "Indirect tolerancing" is not explicitly defined (and there is no reason for it to be) but it means that tolerances are applied indirectly to part dimensions as they control the variation of the produced feature relative to the true position/true profile which the dimension defines.

 

[pmarc]

[...] it's not the colloquial interpretation of what an "indirect" tolerance might be, but the way the ASME Y14.5 standard has defined all tolerances as being direct and defined no tolerances as being indirect that is the reason it's a trick question.

From Y14.5-2009, para. 4.9:
"Geometric tolerances related to a datum reference frame do not take into account any variations in form, orientation, or location of the datum features. Datum features shall be controlled directly by applying appropriate geometric tolerances or indirectly by dimensions such as the size of a primary datum feature of size. [...]"

 

[3DDave]

"Datum features ... controlled indirectly by dimensions ..."

Not tolerances, not dimensions - only datum features.

It's not even clear what that sentence means; are datum features of size not directly controlled by dimensions of their size?

 

[3DDave]

If "indirect tolerancing" is not defined and there is no reason for it to be, then why ever mention "direct tolerancing?" There was never a reason to call anything direct tolerancing at all.

How can it mean anything if it is not defined? Just because one part says one thing parenthetically and another says a different thing explicitly means I give the parenthetical no weight. However, it does make the next sentence perfect, right?

These are good questions to get people to fail to pass the GDTP test.

No matter what, there is some error in the standard that makes every answer wrong. The 2018 version makes it worse.

Anyway, lack of coordination of various subgroups of the committee has been a long standing and, AFAIK, unrepaired problem.

I feel like I should bold words at random. For certain, bolding words that aren't quotes to make it look as if they are quotes is a bold strategy.

 

[pmarc]

3DDave,

Thank you for the discussion.

 

[Burunduk]

The portion of "(or indirectly in the case of basic dimensions)", which is bolded is part of the quote. You can look it up in the original text of the Fundamental Rules paragraph. So if you were looking for suggestions on what indirect tolerances may mean based on the standard, that's as good of an answer as you are going to get. If that's not what you were looking for then I guess any answer will be no more than a personal interpretation. If the whole point was to make rant that's a whole different story.

 

[3DDave]

I was not looking for opinions. I was looking at the definite way it is definitely defined. And in the paragraph 2.2 DIRECT TOLERANCING METHODS it states what are direct tolerancing methods. Reading ANYWHERE else is of Zero importance except to the original premise - Trick Questions.

"May mean" is never a suitable answer.

Burunduk, "tolerances are applied directly to either dimensions or features," et al is not a quote, but the argument you are using about it is called a "red herring." You knew that when you typed that response that you were providing a half-truth, that you indeed did bold items not part of a quote and that I was referring to writing that was not a quote.

 

[Burunduk]

The paragraph DIRECT TOLERANCING METHODS describes what the title suggests - direct application of tolerances.
If you want to understand something else like indirect tolerancing why would you refuse looking somewhere else, such as in the FUNDAMENTAL RULES paragraph as you were suggested?

Sorry if you don't like my explanation methods or the way I bold words to aid your understanding, but everything I said is based on the standard, and you were provided a reference too. FUNDAMENTAL RULE (a) differentiates between directly and indirectly toleranced dimensions. 2.2 DIRECT TOLERANCING METHODS which you are already familiar with describes how tolerances are applied directly to either dimensions per sub-paragraphs (a) and (b) or to features per sub-paragraph (c), hence my statement that "tolerances are applied directly to either dimensions or features" which you appear to have some issue with. If you think I deliberately gave you a half-truth would you mind explaining and support this accusation?

 

[3DDave]

I already explained the factual observation on bolding. Reread it; perhaps diagramming the sentences will help you. Did you think that the word "feature" was key to some insight? Explain why you bolded that word.

Looking elsewhere does not define indirect tolerancing, does it? It uses the phrase in an unexplained manner with no interpretation and is in conflict with explicit sections.

I find it odd that so much effort has been expended looking to read between the lines to find that which could have been explicitly described instead of appearing to be held-over editing errors, much like "true geometric counterpart" was retained in spite of being explicitly mentioned as being replaced by "datum feature simulator".

 

[Burunduk]

Did you think that the word "feature" was key to some insight? Explain why you bolded that word

Yes, the word "features" is a particularly important word in that sentence. It could have helped you to understand that the "elsewhere" use of the phrase to which you refer is not "in conflict with explicit sections", on the contrary - it completes them. The word "features" being bolded versus "part dimensions" bolded later in the same paragraph were supposed to aid the understanding how DIRECT TOLERANCING METHOD (c) that describes direct tolerancing of features - not dimensions, and the mention of the indirectly toleranced basic dimensions in FUNDAMENTAL RULE (a) work together in the sense that indirectly toleranced dimensions are part of the definition of the tolerance zone that applies directly to a feature.

This was in direct continuation to my initial point that there are no indirect tolerances. There are indirectly toleranced dimensions. Hence, title block or any other tolerances can never be considered indirect.

 

[3DDave]

It was MY point that there are no indirectly toleranced dimensions or indirectly toleranced features.

Glad to see you agree.

Bolding to help you see what I mean.

 

[Burunduk]

It was MY point that there are no indirectly toleranced dimensions or indirectly toleranced features.

Seems like you need the bolding or some other emphasis after all because without it you misread my posts. You seem to prefer captitalization:

"This was in direct continuation to my initial point that there are no indirect tolerances. THERE ARE INDIRECTLY TOLERANCED DIMENSIONS. Hence, title block or any other tolerances can never be considered indirect."

 

[3DDave]

If there are no indirect tolerances then there is nothing that can be indirectly toleranced, dimensions or otherwise.

I think if you read what you wrote, twice, then you will see your fundamental error in reasoning.

If you read what I wrote you will see that your replies aren't on topic, not even close. The topic is that the standard has taken what once was an a separate case and eliminated it by adding all cases to it. In addition, poor quality editing of the standard has led you to making bad arguments.

It's a subtlety that escaped you.

Maybe I need to make a trick question not a trick question? Like showing where the ball is under which cup by using transparent cups in a magic act?

 

[Burunduk]

Again, since it is impossible to have an "indirect allowed variation", there is no and there could never be an indirect tolerance.
So what you think "once was a separate case" - the direct tolerance, was never really separate since it was "all cases" from the beginning, even if one case was previously missing in the list.

Indirect tolerancing of a feature is impossible. Indirect tolerancing of a dimension, considering Fundamental Rule (a) in the 2009 and 1994 versions, is when a tolerance as direct as all of them are applied to a feature that the dimension defines.

If you read what I wrote, twice, you would see that.

All that is based on the terminology used in the standard, not on someone's opinion or someone's liking or disliking of how the standard is written.

"Trick question" or not, that is the answer.