GD & T Callout Convenstion 1

[REDesigner09]

Hi,

I have a couple of quick question,

What's the standard for Datum, Sectional, Detail or Directional callouts?

If I use Datum A, can Section A-A, Detail A & so forth, also be used?

Also, I'm told that according to:
ASME standard for view names (ASME Y14.5M-2003), states that letters I, O, Q, S, X and Z are not used

Is this still true for newer or current standards?

Thanks

 

[drawoh]

REDesigner09,

My copy of ASME Y14.100-2004, in "NONMANDATORY APPLENDIX_D", in section D-9.5, states that "I", "O", "Q", "S", "X", and "Z" shall not be used.

Note the term "nonmandatory". I don't recall this being nonmandatory in DOD-100.

JHG

 

[REDesigner09]

Hi Drawoh,

Thanks for the feedback. It apppears as a best practice, it shouldn't "I", "O", "Q", "S", "X", and "Z" be used.

Is there any reference to how many times a letter can be used per the example I gave above?

Thanks

 

[KENAT]

You want to check out ASME Y14.3-2003 especially section 1.7.3 & 3.2.2 - "I", "O", "Q", "S", "X", and "Z" shouldn't be used.

It talks about 'Identifying Removed Views' & 'Identifying Sections" without explicitly saying not to reuse the same indicators for the different types of view. However, I wouldn't re use them due to potential for confusion.

If in doubt, avoid reusing designators on drawings whenever possible, as if helps minimize the potential for conclusion.

Posting guidelines faq731-376

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What is Engineering anyway: faq1088-1484​

 

[REDesigner09]

Hi Kenat,

That's what I figured to. I don't have access to this particular ASME standard, which is the reason that I'm asking or verifying.

Thanks

 

[PeterStock]

The use of letters for different purposes is someting that is left up to internal company standards. Our major client uses three lists, one for views, sections and details, one for datums, note references and field references (different symbols apply for the three but there can not be a datum A and a note reference A or field reference A at the same time) and one for dimensions. I have also seen some companies use one list, if A is used for a datum, it can not be used for a view or dimension. I would suggest that if you do not have a standard either establish one formaly or at least establish one informaly for your own use. If there is any confusion, change one of the letters, there cheap.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[looslib]

One company I worked for started section views from A going forwrad and detail views from Y going backwrads.
Datums started at A going forward.



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

Ben Loosli

 

[REDesigner09]

Hi Everyone,

Thanks for the feedback & I like your suggestions.

My dilemma now is that I have casting & machine drawing that was created some time a go & use Y14.5- 1982 standards.

With these drawings, there is clear evidence that callout letters were used twice for two different section views. Additionally, some views have a section view with multiple other section callouts in it.

I'm going through the process to try to clean up these drawings & hopefully, at the same time, develop some standards.

I created a template to track callout letters, which helps a little bit.

Any suggestions what the best approach would be?

 

[fcsuper]

As long as the drawing is clear about which is what, there should be no issue with reusing letters for different purposes. Many CAD packages don't pay attention to this for you, so it is often easier to just allow reuse.

I've never had a discussion with anyone who confused a datum reference with a section view, but I'm sure someone somewhere might've at sometime.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[REDesigner09]

Hi Matt & Others,

With particular drawings that I have, there were multiple section callouts with the same callout letter's. Not so much an issue, but there wer also datums wit similar designations, such as Datum Z & Datum Z1, both happen to be in the approximate same area to.

This is primarily what I need to clean up, in addition to clarifying the views better.

I was just checking what the current standards are, regarding Datum, Sectional, Detail & Directioanl callouts.



Thanks Everyone...

 

[KENAT]

Your mention of Z & Z1, you don't have some datum targets in the mix do you?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[REDesigner09]

Hi Kenat,

Nope, the original drawing both call for Datums.

 

[Belanger]

Kenat is saying that if you aren't using datum targets, then it isn't kosher to have a datum be called "Z1."

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[REDesigner09]

Hi Belanger,

I agree & will be changing.

 

[REDesigner09]

Hi Everyone,


I contacted a GD & T specialist & here is what I am told:

I am not aware of any that limits using the same letter for datum feature identification, section labeling, etc. The applications are different enough that there should be no confusion. I did do a search of the applicable standards and didn't find any such rule.

Letters not allowed according to the ASME Y14.5 standard for datum feature identification are I, O and Q. From ASME Y14.5-2009: 3.3.2

Datum Feature Symbol .......Letters of the alphabet (except I, O, and Q) shall be used as datum identifying
letters. Each datum feature of a part requiring identification shall be assigned a different letter. When datum
features requiring identification on a drawing are so numerous as to exhaust the single alpha series, the double
alpha series (AA through AZ, BA through BZ, etc.) shall be used and enclosed in a rectangular frame. Where
the same datum feature symbol is repeated to identify the same feature in other locations of a drawing, it need
not be identified as reference.

The Y14.3-2003 MULTIVIEW AND SECTIONAL VIEW DRAWINGS standard does not allow I, O, Q, S, X and Z for view identification. Here is the section from that standard.

1.7.3 Identifying Removed Views. To relate the viewing plane or cutting plane to its removed view, capital
letters such as A, B, C, etc., are placed near each arrowhead.

The corresponding removed views are identified as VIEW A-A, VIEW B-B, VIEW C-C, etc. View letters
should be used in alphabetical order excluding I, O, Q, S, X, and Z. When the alphabet is exhausted, additional
removed views shall be identified by double letters in alphabetical order, as in AA-AA, AB-AB, AC-AC, etc

There was not a revision of the Y14.5 standard in 2003. The Standard came out in 1966 and has had revisions in 1973, 1982, 1994 and 2009.