ASME Y14.5 For General Dimensions and Tolerancing 5

[Shuttle128]

At most companies I've worked for we have included a general note in engineering drawings that states something along the lines of "Interpret Drawing per ASME Y14.5" as a general note included in all drawings regardless of whether GD&T feature control frames or datums are defined in the drawings. My understanding has always been that even if GD&T is not used in the drawing, the Y14.5 standard still provides a basic definition of drawing dimensioning and tolerancing for general dimensions and features so that the fabricator knows how to interpret the drawing.

I was recently asked to remove the standard note from a drawing by a peer and was surprised to learn that this engineer's interpretation was different from mine in that they believed that applying this note was only necessary if GD&T specific features were used on the drawing.

If I'm in the wrong, please help me change my mind. Otherwise, some support would be nice!

 

[Brian Malone]

I don't have the 2018 version, but 2009 definitely states in the scope: "This Standard establishes uniform practices for stating and interpreting dimensioning, tolerancing, and related requirements for use on engineering drawings and related documents."

Certainly GD&T are explained and elaborated on but the standard explicitly defines in sections 1 & 2 general dimensioning and tolerancing definitions, forms, and applicability. The use of the ASME Y14.5 note is appropriate regardless of GD&T being used or not used on a drawing.

 

[Wuzhee]

2018 says this:

1.1 INTRODUCTION
This Standard establishes symbols, rules, definitions,
requirements, defaults, and recommended practices for
stating and interpreting dimensioning, tolerancing, and
related requirements for use on engineering drawings,
models defined in digital data files, and related documents.

Also in chapter 4:

Dimensioning and tolerancing shall clearly define engineering
intent and shall conform to the following:
(a) Each feature shall be toleranced. Tolerances may be
applied directly to size dimensions. Tolerances shall be
applied using feature control frames when feature definition
is basic. Tolerances may also be indicated by a note or
located in a supplementary block of the drawing format.

(b) Dimensioning and tolerancing shall be complete so
there is full understanding of the characteristics of each
feature.

Some examples. Even if you don't put basic dims and fcfs on, you have to follow Y14.5. Therefore displaying the used standard is necessary for people outside your company who encounter your drawing somehow.

People tend to forget about the "Dimensioning" aspect of Y14.5 and focus solely on "Tolerancing". Hence the confusion between you and your peer.

 

[3DDave]

"GD&T" is marketing speak that really means nothing in the standard; it remains in the Foreword because many of the members of the committee are involved in the sales of training or software and their jobs depend on that identifier.

The use of Feature Control Frames (FCFs) is the difference.

The clue is the title "Dimensioning and Tolerancing," not "GD&Ting"

As noted above, it guides in more than the use of Feature Control Frames and the related Datum Feature Symbols (which may be optional, but are not used without the FCFs.)

 

[Stroleous]

There is also a document out there ASME PDS-1.1-2013 that states if no reference to a standard is referenced on the drawing (company, regional, national or international), that the latest version of ASME Y14.5 for interpretation. Not sure how that is enforced but take it for what it's worth.

 

[ctopher]

I have "INTERPRET DIM AND TOL PER ASME Y14.5-2018" near the title block on all drawing templates.
A couple people tried to remove them, but they are the one's that either don't want to follow it or have "standards" knowledge.
It stays if they want it or not.

Chris, CSWP
SolidWorks
ctophers home

 

[drawoh]

Shuttle128,

ASME Y14.5 explains the meaning of everything on your drawing, including the [±][ ]dimensions. It is the ASME standard for dimensioning and tolerancing. There is no mention of GD&T on the cover.

--
JHG

 

[Burunduk]

There are no engineering drawings where "GD&T is not used", except for those drawings that do not have even a single dimension or tolerance. Regardless if +/- or geometric.

 

[Shuttle128]

Thank you for the support. I was hoping I wasn't crazy, though it looks like it may be an uphill battle to convince others in my department. I appreciate all the responses.

 

[ewh]

Is there a company document defining drawing interpretation? How do the others in your department define miscellaneous symbols and notations? Are you allowed to use those symbols on your drawings without any definition? Do you have to spell out "DIAMETER", "DEPTH", and "COUNTERSINK"? How do the others defend their interpretations without a standard of some kind??

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

 

[3DDave]

It is odd that human societies came about long before writing much less standards. Traditions can be passed on by spoken stories and existing examples and hands-on training. Many drawing concepts pre-date and were copied into the Y14 series.

 

[drawoh]

3DDave,

I have prepared a number of drawings of rectangular pieces with no additional features. I put [±][ ]dimensions on them and I am done. Rule[ ]#1 does the rest.

--
JHG

 

[Shuttle128]

Is there a company document defining drawing interpretation? How do the others in your department define miscellaneous symbols and notations? Are you allowed to use those symbols on your drawings without any definition? Do you have to spell out "DIAMETER", "DEPTH", and "COUNTERSINK"? How do the others defend their interpretations without a standard of some kind??

This is a good point. There is such a document. In our case the company document refers in large part to Y14.5. In our case though, our drawings are sent to outside customers who generally don't have access to this document and is considered proprietary. It's my understanding that our department uses the standard note to use Y14.5 directly because of this.

It is odd that human societies came about long before writing much less standards. Traditions can be passed on by spoken stories and existing examples and hands-on training. Many drawing concepts pre-date and were copied into the Y14 series.

I had the same thought about interpreting dimensions and tolerances. There is so much tradition that predates the establishment of standards when it comes to drafting standards that I was hesitant to argue for the requirement for inclusion of Y14.5. One of the reasons I posted here. Is tradition and expectation enough to be sure there isn't some ambiguity in our drawings that we miss by not referring to a standard?

 

[3DDave]

drawoh, the point I made in that first reply was not that. The point was that no one can put "GD&T" on a drawing and what they usually mean is "Feature Control Frame."

That said, the tolerances on the implied angles on the rectangles are usually derided as ambiguous and uninterpretable. However I was peripherally involved in a major TACOM contract that had removed all tolerances for implied 90 degree angles; not one angle tolerance for them at all. No one noticed. Not TACOM, not the fabricators, not the inspectors, not the drawing checkers.

 

[jassco]

Hi, Shuttle128:

This statement below is strange:

"In our case though, our drawings are sent to outside customers who generally don't have access to this document and is considered proprietary."

If you don't want your customers to see your proprietary document, then you should not indicate it on your prints. Otherwise, your prints are not fully defined.

Best regards,

Alex

 

[3DDave]

Shuttle128,

Is tradition and expectation enough to be sure there isn't some ambiguity in our drawings that we miss by not referring to a standard?

I'll suggest this: have there been any problems directly traced to ambiguity? Tradition is how entire homes are site-built.

What I do see is that there are few efforts to perform tolerance allocation based on structural or other mechanical requirements and most are just making the holes line up. The problem being is that if clearance is allowed so the holes can line up to get the fasteners through there are rarely explicit next-level assembly constraints applied to ensure the clearance isn't applied to mis-orientation. The majority focus is on making life easy for inspectors and not on ensuring the product functions. Worst is recasting the requirements when CMM software cannot handle the correct requirement. I expect functional tolerance analysis isn't part of your current position.

Just wait for the crap to hit the fan and leave it off until then. Make sure to write a polite CYA memo now to whoever needs to see it that you were directed to remove the note and was told it was not required.

 

[Shuttle128]

If you don't want your customers to see your proprietary document, then you should not indicate it on your prints. Otherwise, your prints are not fully defined.

We don't. Hence the reference to Y14.5 (at least by my understanding).

Just wait for the crap to hit the fan and leave it off until then. Make sure to write a polite CYA memo now to whoever needs to see it that you were directed to remove the note and was told it was not required.

This is basically where I've arrived at this point. For this particular issue, the drawing is simple and not much could cause problems. If I were to apply this to every instance it might come up, it could be a bigger problem eventually. I'll make sure my complaints are documented in the meantime. Thanks for the advice.

 

[drawoh]

Shuttle128,

There is anther issue here. Billy Bob and Cousin Elmo's General Industries send out drawings that reference BBACE[‑]00234 Dimensioning and Tolerancing.
[ol]
[li]Billy Bob and Cousin Elmo must send a copy of the standard out with any drawings they subcontract[/li]
[li]Billy Bob and Cousin Elmo must train their vendors in their standard, explaning all the symbols, and any interpretation issues, like Rule[ ]#1. ASME[ ]Y14.5 is way easier for everbody involved.[/li]
[/ol]

--
JHG

 

[ewh]

A major reason to state how the drawing is defined is legal CYA. I always consider a drawing as a contract, and if the terms are not defined I can't push back when a supplier interprets it differently, other than not using that supplier in the future.

"Know the rules well, so you can break them effectively."
-Dalai Lama XIV

 

[3DDave]

I've had people push back on Y14.5. It's not a panacea. Usually it's over crappy datum feature selection and, when I point out what could be allowed, the answer is "They wouldn't make it that way." So much for controlling what would be acceptable.