How to draw an unambiguous specification of chamfer

[USB Memory]

Hi all

I'm puzzled about to be an unambiguous specification of dimension and angle.

How do you all draw a chamfers in your company or yourself?
I picked some sample pictures as followed.
First one is ambiguous and second one is unambiguous sample.

Thanks

 

[jackk]

In most cases, chamfers are not critical features of a design so tolerances are not specified as part of the chamfer dimension. The general tolerance applies.

If a chamfer is critical, then a tolerance is applied to either the angle or the length, but not both. Or the chamfer is dimensioned as two lengths (no angle).

 

[USB Memory]

Thank you for your quick response.

Usual method is just it that "tolerance is applied to either the angle or the length, but not both. Or the chamfer is dimensioned as two lengths (no angle)".
In my place, it's taken usualy as well.
but ASME mentiones something about those FILLETS, CORNERS, CHAMFERS, AND CONES may be specified as written above, but are not fully defined and may result in ambiguity.
This ambiguity may be clearly defined by using profile tolerancing.
I am not much familiar with using profile tolerancing.
then if someone has experience to take unambiguous specification of dimension and angle in accordance with ASME, I'm going to use it as an reference.

thanks

 

[3DDave]

Why are you believing it is "ambiguous" to use one each of the linear and angular tolerances. It creates a trapezoidal zone, potentially the same as if two linear dimensions were used.

 

[USB Memory]

Because ASME says somthing about ambiguous of chamfer on [1-4 FILLETS, CORNERS, CHAMFERS, AND CONES].
To clarify, it's seemed to be necessary to use positional tolerance or profile tolerance or both.
Unambiguous specifications is saied in ISO 14405-2 as well.
I think Unambiguous specifications is important for automation.
If the work is eternally done by humans, I think that it is not necessary to be Unambiguous.
Because we can understand the hidden meaning.

thanks

 

[3DDave]

ASME does not use the word "ambiguous," at least not in ASME Y14.5-2009. I don't recall seeing it in the 1973, the 1982, or the 1994 versions. I don't have a copy of the 2018 version. I have no information on ISO documents.

Why do they claim it is ambiguous? There is no hidden meaning.

 

[USB Memory]

The word "ambiguous" is used in ASME 2018 MANDATORY APPENDIX.

It is too hard to explain about "ambiguous" for you.
That's why I'm asking you all abou that here.

thanks

 

[3DDave]

"I don't have a copy of the 2018 version." is exactly what I wrote. Is it impossible for you to read replies?

Also, and this is a pet peeve but, PUT THE EXACT REFERENCE IN THE ORIGINAL QUESTION.


Why do they claim it is ambiguous?

 

[3DDave]

NEVER MIND, LOOKING AT DELTAS TO THE 2018 DOCUMENT - ALL PLUS-MINUS TOLERANCES ARE CONSIDERED AMBIGUOUS NOW. SO IT'S NOT JUST ABOUT CHAMFERS.

That means that the second example in your original post is also ambiguous.

 

[USB Memory]

I read your writting and then I added some information about " ASME 2018 MANDATORY APPENDIX".
I wonder Why you thought about old version because new one has been released.

Anyway you try to solve my problem about "ambiguous" and I am very grateful for that.
Next time I will write in more detail like version info.

As you think, the second example (from ISO) is ambiguous I think too.
So I want some example for deepen understanding as my original question "How do you all draw a chamfers in your company or yourself?",
because the standard is new and then there are few information about that.

thanks

 

[3DDave]

Simple - 99% will ignore the new standard for features like that. And 99% of all drawings are not interpretable under 2018, so being the "latest" counts for nearly nothing.

The committee mostly exists to make money for committee members selling training and books and consulting. This is a great way to do that - make useless distinctions. It is also intended to move from hard gages to only accepting answers from CMMs, which means more CMM sales and updates for CMM software. A lot of them have been at this since the 1980s and this is the chance to make one more big income before retirement. It also forces people to update their CAD and CAM software to be compatible. Win-win.

Label every surface as a datum feature and reference whatever surfaces are neighbors of the chamfer as datum feature references. It will not be "ambiguous" and you will triple your effort at documentation and triple the effort of the inspectors and machinists for no discernible improvement in function.

 

[USB Memory]

It must be true that there are few pepole to accept amd use the new standard As of now.
I can also image to increase person-hour.(becase we don't know much about this)
but in the future, the unambiguous can be important for automation technology.
This standard is new and therefore the content makes money At least on my country becase I'm going to take a seminar about this.

Thanks

 

[3DDave]

There's the problem. You should not need a seminar. If the standard explained itself correctly you could reach your own answers. Different instructors will give different interpretations and few people will get seminars at all. It's not ambiguous to parametric modelers, so there's no problem with automation technology.