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GD&T standards


New member
I'm in the middle (right now) of a GD&T class based on ASME Y14.5M-1994. Is there another standard due out within the year? It seems I remember hearing something about one in an earlier forum.

Steve C
The current standard is up for review in '03 and revision in '04. The review notes and possible revisions will be released for comment to the public later in '03. From what I hear, one of the main changes is the possibility of replacing the US Rule one standard with the Iso envelope standard.
Also due out next month is ASME Y14.41 - Digital Product Definition Data Practices. This is touted as the first global guide to modeling on a computer in 3D.

It establishes requirements and references documnets applicable to the preparation and revision of digital product definition data, or data sets.

Brad H
Yes, Brad and another forum a couple of months ago asked the question: Is PTC gearing itself towards that specification? Those of us just getting started with Pro/E or seansoned veterans like many in this forum would like to see what PTC is doing to meet the new spec.

Steve C
Is ASME Y14.14 going to cover keynote drawings where only special dimensions are drawn? All other dimensions would be to a boilerplate note like dimensions not shows shall be per std 1561A0349 where 1561A0349 is an internal tolerancing spec.

Personally, I don't think that keynote drawings can possibily portray the dimension and tolerance requirements sufficiently. Any one out there have an opinion on this practice?

Keynote drawings are an attempt to capitalize on electronic data to simplify drawings. For example, whereas a complex brazed chassis, could require 500 dimensions to fully describe it, a keynote drawing would show only those dimensions critical to form, fit, and function. The remaining dimensions are in the electronic data. A note on the drawing says something like: dimensions not shown shall be per std 1561A0349 where 1561A0349 is an internal tolerancing spec. Another note, would say something like: for nominal dimensions not portrayed, see Pro/Engineer file 321B1267.ASM.73.

Disadvantages are:

A. You don't have a single source for dimensional data.

B. When you need dimensional information for a released part, you may have to open the part file which may be locked away somewhere where you can't get it in time; it leads one to make assumptions or to go to unreleased part files for the information.

C. Inspectors (or anyone else downstream from you) have to know how to use Pro/E in order to query the models for dimensions.

Conservative guy that I am, I prefer a fully dimensioned drawing!
Sounds very like vendor item or source control - these work but only the dimensions called out are required to be checked.

One big issue I can see is that of using drawing created or driven dimensions.

According to one of the polls here, a large percentage of users rely on driven dimensions for a large part of their drawings - if they don't use these do you think they're putting tolerances on model dimensions and using correct datum structure/dimensioning scheme ??

Driven dimensions can only exist in drawings so what happens without them ??


Is there any chance of actually being able to view previous polls ??
will store created/driven dimensions in the part model instead of the drawing file

So we can probably double-dimension in models - gets better-and-better :-(
How can I get a hold of a printable version of these standards? Hopefully without paying???????

I've NEVER had to hold to standards... However, my nature of work is so exclusive, that I realy don't need to worry about it, but I would like to be able to have a guidline to run by to keep my machinists happy, and to keep the archived drawings to standard.
>>Is there any chance of actually being able to view previous polls ??

Not easily. The best way is to go to the home page and put your cursor in the poll window and hit CTRL-R to refresh the poll window. Then wait for the poll you want to look at to come up. There are some things I like about this poll script, but some things that I don't, and this is one of them. Anyone have any suggestions for another poll script? My platform preference is, in order, ASP, PHP, CGI.

If you want me to put other polls in a forum message, just let me know. Also, if you have any suggestions for more polls, email me personally by clicking on my name to the left.

I can manually put one in place here for convenience:


<script language=JavaScript src=/absolutepmxe/xlaabsolute.asp?p=7></script>
Tunalover, FYI:

Keynote drawings are not covered by ASME Y14.24 (Types and Applications of Engineering Drawings).
We use alot of keynote drawings for our extremely complicated blended parts, specifically stylized plastic parts. Most of these parts are rotomolded and our vendors use our solid models to create the molds. Our drawings are primarily for inhouse QA to accept or reject these parts before allowing them into production. I really don't see anyother way to relay this information as accurately to our vendors, the models are fed directly into their CNC program. Besides the minimal machining tolerances, there really isn't any excuse for variations between model and product besides a mistake I made in creating the model.

After all that, I think that keynote drawing need to be addressed in the new standards. Although I am open to anyones suggestions on how they would handle they type of parts I am dealing with.