The "purpose" for definition of FOS and AME (ASME Y14.5 2009) Conical /Tapered features 3

[dtmbiz]

Unfortunately the ”purpose” for the need to define certain and specific terms and concepts", which would be helpful in determining the “intent” of the standard’s definition regarding inclusion and /or exclusion for features considered in respect to those definitions and concepts. More specifically regarding FOS and AME for this discussion relative to conical and tapered features.

Here are my general points for discussion. I hope others will post theirs.

Purpose of FOS: (Feature of Size) My understanding of its purpose is to identify features that have center planes, axis and center points in order to locate and orient tolerance zones.

Purpose of AME: (Actual Mating Envelope) My understanding of its purpose is to establish a produced FOS’s actual location and orientation of it’s center plane, axis or center point by use of a AME Datum Simulator (gage) in order to verify compliance with the defined tolerance zone by comparing the true feature's vs. the produced feature's location and orientation of axis, center plane or center point.

It is also my understanding that applied geometric controls to an FOS, “other than size” can only be verified after the produced feature’s has been verified to be within size limits.

Conical and tapered feature’s: In a previous thread (thread1103-460248) there are arguments that conclude that these type features cannot be classified as features of size because in the case of a cone (conical feature) there is a limit to expansion or contraction about the apex, and similarly a limit to intersection of tapered surfaces beyond their intersection.


Disagreement with argument that 'conical and tapered surfaces are not FOSs because an AME cannot be defined":
Conical and tapered surfaces can and do have an AME in the physical world (vs a purist mathematical theoretical world) which can identify a produced FOS axis or center plane.
The AME’s Datum Simulator would not expand or contract beyond the limit of the apex of a conical surface or intersection of tapered surfaces whether or not they actually occurred within the size limits of the feature’s extent. Concluding that the apex of a conical surface and the intersection of tapered surfaces would be to one side of the tolerance limits and would be the minimum or maximum allowance which therefore would be the minimum or maximum limits of contraction or expansion of an AME. (internal / external feature). Expansion or contraction is limited to be within limits of size vs. infinite or unlimited

**** Also would like to mention in relevance to the FOS definitions, specifically around the standard's use of “may”, and the definitions of words ; may, must , will, shall in the engineering environment (English that is). “May” is a permission word that “allows” and is not mandatory. “Shall” is a “mandatory requirement” which is not used in definition of FOS

 

[Burunduk]

No - he was upset that I was misusing "truncation" so much so that he went and searched for pictures to hammer the point. People who aren't upset just put in a link.

I am in awe of this accurate and in-depth psychological analysis. You forgot to mention though that those who are really desperately mad, embed a video in their post.

 

[dtmbiz]

3DDave
Nice...

There is no cone "above the apex" so it cannot be cut there. The apex of a cone is the highest point. Just draw a picture.

Gee...guess I forgot to mention the cone was an internal conical feature that was being viewed down on in my picture.

So I suppose people have a lot of trouble eating ice cream from a cone in your world.. pretty messy with the cone apex pointing up

 

[Burunduk]

3DDave, jokes aside, as I already said I wasn't upset at your use of the term "truncation", I didn't realize that you weren't using the term the same as I interpret it until you explained. I'm sorry if there was any negative undertone.

What is your opinion on application of position tolerances on countersinks? You object, right? What would you suggest instead? See examples on page 89, figures 8-49, 8-51 in the below "google books" preview:
Interpretation of Geometric Dimensioning and Tolerancing, by Daniel E. Puncochar, 1997, Industrial Press Inc.‏
The description says the book is based on the '94 standard.