Is dimensioning/detailing in isometric view acceptable??

[KENAT]

My senior design checker and I are trying to determine whether dimensioning/detailing parts and assemblies in isometric views is acceptable to the standards (ASME Y14 series).

Looked through 14.3 and the first part of 14.5 and didn't see it explicitly stated.

Both of us are of the opinion it's generally a bad idea and we don't like it but we're trying to verify whether that's actually based on the standards or just ingrained prejudice!

If anyone knows for sure the answer or where we need to look please let me know.

(Plus for now can we stick with the world of 2D drawings, obviously this question doesn’t really make sense for MBD.)

 

[looslib]

Check out Y14.41


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli
Sr IS Technologist
L-3 Communications

 

[KENAT]

From my limited knowledge of what Y14.41 is about doesn't it refer to digital information, especially 3D?

I'm talking about 2D drawings that effectively get 'printed' albeit normally to pdf not hard copy.

Would 14.41 still be applicable?

Ken

 

[ewh]

Ben is correct. While it doesn't specifically address assembly drawings, it does allow for detailing of axonometric views.

 

[KENAT]

We've been talking about trying to get a copy of 14.41 for a while now, maybe now's the time then.

Thanks to both of you,

Ken

 

[ewh]

You should try to get a copy of 14.41. It doesn't only involve 3D modeling, but also covers the drawing details of the MBD. In addition, there are updates to GD&T that will probably be included in the next release of Y14.5 (profile tolerancing for example).

 

[pennpiper]

Here we have yet another case of a general question with no specifics and a bunch of general answers that may or may not address the object the questioner had in mind.

The detailing and demension is normal subject specific.

Example: complex piping systems are best displeyed in isometric. They can easily be detailed and demensioned in the isometric view.

So what is the object being detailed and demensiond?

 

[ewh]

Complex piping systems may be more easily defined in an iso view, but I would suggest checking the applicable standard to determine if they are allowed.

 

[KENAT]

It was an intentionally general question. It isn't regarding a specific drawing or application. We are in the process of setting drawing standards for our section of the company and it was in support of this I was raising the query. Currently they don't have any real standards, they don't even really follow the Y14 series.

Piping is one of the areas our checker said he had extensively used dimensioning in iso views. We don't really do that type of piping, I perhaps could have put that in my original post but was just trying to get a feel for peoples standard practices and if we'd missed something in the standards someone here knew.

There are a few regular posters here who’s opinion I am beginning to value and wanted to see what they or anyone else had to say.

If this is the wrong place for a general question then please direct me to the right forum, I’m fairly new to eng-tips so apologies if I’ve broken a rule I was unaware of.

If there isn’t such a forum then maybe I’ll look at starting one if there would be any interest.

 

[CoryPad]

KENAT,

This is the correct forum, and you have not broken any rules.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ewh]

This is as good a place to ask the question as any. I don't have access to a copy of the ASME standards pertaining to drawing views, but per the Genium Drafting Manual (which is based on these standards), isometric drawings are allowed, and are considered pictorial drawings, "which may be prepared to completely replace or avoid preparation of conventional drawings". Hope that helps!

 

[namdac]

Dimensioning in an Isometric view is acceptable, if it is to show information that can not be shown by any other views. Couple of things to remember is that, do not under any circumstances dimension Hidden Lines. Also do not double duty extention lines. I had a teacher or I could say Drafting Preacher who stated that he would break our finger if we ever double dutied extention lines. There again I have dated myself, sorry did'nt want to give a history lesson.
Regards,
Namdac

 

[ewh]

What is "double dutied"?

 

[KENAT]

ewh,

Thanks for the tip on the Genium Manual, I'll have to take another look at it as I obviously missed something.

We looked at getting a copy of 14.41 but aren't sure we can justify the cost at the moment, both my checker and I are keen to get a look at it though.

namdac,

Totally agree on hidden lines, I rarely even use them and certainly don't dimension to them. I too don't get what you mean by 'double dutied', I even asked my checker (who's been around plenty long enough to hear of most things) and he wasn't sure so If you could clarify that would be great.

Ken

 

[aardvarkdw]

Most of the time a feature is not shown true size and shape in an isometric or axonometric view. Only features that are shown true size and shape should be dimensioned, with the exception of a dimension shown not to scale which should be underlined. NTS dimensions are usually used on long parts (EX: shafts) that have been shortened to fit on the page.

Namdac- "Dimensioning in an Isometric view is acceptable, if it is to show information that can not be shown by any other views." I have never come across a feature that could be dimensioned in an isometric view but not in a standard or auxilary view. Somethings may be easier to show in an iso view but I wouldn't say that it was a recommended practice. At most I might use an iso view for a reference dimension.

 

[ewh]

On the board, you are probably correct, but in today's cad systems, it is a simple matter to show an accurate dimension in an iso view, and per 14.41, it is correct. Pictoral drawings, while not common, are none the less acceptable. Of course, I'll eat my words if you can prove otherwise in the accepted ASME standards.

 

[aardvarkdw]

Ewh,
I must concede to you being as I do not currently have a copy of the ASME standard (I am working on remedying that). I did not say however that it was not acceptable. I did say however that I would be hard pressed to find an example in which I was able to dimension something pictorialy and not orthographicly. I will say that a pictoral view with the exception of something drawn entirely in compliance with Y14.41 (which I have not read but I infer to be concerned primarily with 3d drawing files not 2d drawings), in many cases is not capable of comunicating all information nessesary to completely describe a part. I would have a very hard time accepting a mostly orthograpic drawing with some features dimensioned in a pictoral view, or vice versa.

 

[ewh]

Y14.41 provides for actual drawings where the dimensions and tolerances are in the model, and the views containing them can placed on a drawing. I agree that it would be difficult to accurately dimension an iso view on a drawing (depending on the software), but since out of scale dimensions are allowed, this should not be a problem (provided you know what the correct dimensions are). The OP pointed out piping drawings, and this seems like a good example for a pictoral drawing.

 

[KENAT]

One thing that's occured to me.

We reference Y14.5 on our drawings. We don't reference Y14.41.

Therefore I guess what Y14.41 says isn't necessarily directly relevant.

That said we use a lot of the y series standards we don't directly reference to influence our drawing standards so maybe what I said doesn't make sense.

 

[ewh]

14.5 references several ANSI/ASME standards, but you are correct in that it does not yet reference 14.41. Give it time