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

 

[3DDave]

dtmbiz - never shipped UPS*? I only accuse you of taking the least likely interpretation and running with it.

"What could that possibly mean?"

Exactly that argument style.

*UPS actually uses smallest section perimeter + length to accept shipments, rather than adding them, but maybe you never used UPS. But clearly "adding" is a math operation you know about and rectangular prisms is something you know about and that rectangular prisms have 3 dimensions is something you know about, so how you cannot possibly imagine adding the three measurements leads me to believe that you have no interest in listening.

 

[dtmbiz]

3DDave

The below is truly serious. I am not "playing" or attempting to ruin your point.

If you believe asking sincere questions is an "argument style", yes I am guilty.
If you believe that people can read your mind... I am one that cannot.
If you believe that your statement was taken as a literal cardboard box... I did not "get it" and was "imagining" in the context of solid geometry shapes.

There are 2 boxes. "Each have linear dimensions that add to the same value."

You cannot actually mean that I was supposed to understand that 2 boxes and linear dimensions that add to same value = the width, height and length of UPS boxes?
If you would have offered me $10,000,00 to get that answer; I would have lost out on $10,000,000

If Burunduk is correct about some values for "boxes" having values for height and width, and you were referencing determining the "perimeter" of each... missed it entirely
I have shipped UPS on occasion and did not know how they calculate acceptance as you described above.

Because I truly did not understand you, the conclusion is that I don’t want to listen to you? Not true.

As a matter of fact I am somewhat intrigued as to what your point is.

I must admit I am smiling a bit because you actually seem to believe I am not serious about trying to understand your post.

 

[pylfrm]

Burunduk,

I wouldn't say any of the toleranced dimensions in ASME Y14.5-2009 Fig. 2-19 control conical surfaces.

In (a) they control:[ul]
[li]a cylindrical surface[/li]
[li]the relationship between a planar surface and a circular edge[/li]
[li]a circular edge[/li][/ul]

In (b) they control:[ul]
[li]a cylindrical surface[/li]
[li]the relationship between a planar surface and a circular edge[/li][/ul]

Admittedly, I don't know how "AMERICAN STANDARD TAPER #4" is defined in whatever document that would be. Perhaps it's ASME B5.10-1994?


dtmbiz,

The following equation defines a conical surface in a Cartesian coordinate system:

z = sqrt(x^2 + y^2) / 0.15​

Note that the constant 0.15 is a pure number, not a length, and that it is the only constant involved.

Can you describe a conical surface which is smaller or larger than this one?


pylfrm

 

[Burunduk]

pylfrm, I'm following you regarding what the toleranced dimensions apply to in fig. 2-19. However, according to the standard, this is indeed a way to specify a conical taper, and when it is specified this way in the drawing, it is considered fully defined. The point is that there are other options other than a profile tolerance.

.
A conical taper may also be specified by one of the following methods:
(a) a basic taper and a basic diameter (see Fig. 2-21).
(b) a size tolerance combined with a profile of a surface tolerance applied to the taper (see para. 8.4.2).
(c) a toleranced diameter at both ends of a taper and a toleranced length. See Fig. 2-19, illustration (a).
(d) a composite profile tolerance.

Of the four options 2 involve profile and 2 do not.
Regarding option (c) described by the figure 2-19 I posted above: it says "toleranced diameters at both ends of the taper". Arguably the ends of the taper are part of the taper (the limiting circular elements). One of these dimensions also describes the size of a neighboring cylindrical feature - this dimension works for the definition of both features.

Also note the mentioning of size tolerance in option (b)

 

[dtmbiz]

plyfrm

How does a constant within your posted equation for cone definition within a Cartesian coordinate system, compare with defining a conical feature per solid geometry definition of a cone which includes base, height, angle and axis?

Applying specific values to base, height and angle to define volume of any specific cone (1/3 ∏r²h) is a means of proof that a conical feature has size in the context of Y14.5 2009.

I am not following your logic or reasoning; which is to explain that a conical feature is not an irregular FOS?

What is that you specifically disagree with about my reasoning that a conical feature is a Y14.5 2009 irregular FOS

 

[3DDave]

dtmbiz - back to square one. What single value is put into an inspection report to uniquely describe the size of a cone? What single value is put into an analysis that shows the effect of that individual variation?

Just because some committee members opened a can of worms is not any reason to not put them back and solder it shut again.

OTOH you are clearly able to dump those worms into whatever organization you work for or with and let them figure it out.

Still waiting for a summation paper, which would have been the right way to start this in the first place.

 

[pylfrm]

How does a constant within your posted equation for cone definition within a Cartesian coordinate system, compare with defining a conical feature per solid geometry definition of a cone which includes base, height, angle and axis?

I don't really know what you mean here, but I'll take a guess and try to provide an answer:

The constant 0.15 in the equation is the tangent of the half-angle of the conical surface. This compares with the constant 0.3 in ASME Y14.5-2009 Fig. 2-21 which is two times the tangent of the half-angle. The equation is an alternate method to provide the information that the conical taper symbol and value provide in that figure.

I am not following your logic or reasoning; which is to explain that a conical feature is not an irregular FOS?

My post did not contain any logic or reasoning. It was a question. Was it not clear?


pylfrm

 

[dtmbiz]

pylfrm,

Threads go can back and forth so much and then off at times to tangent discussions which are raised; it is helpful to be clear regarding subject.
Personally, I am a huge advocate regarding being clear about the "context" because of its great importance and relevance to questions or statements.
The essence of engineering is communication.

Not to be "nonsensical" or off topic, but rather to illustrate my point, let’s say a beekeeper makes a statement like; "Let’s eat honey".
You cannot be certain if the statement is made to "literally eat honey" or if it's an affectionate request for "time to eat".

I believe 3DDave in an above post was frustrated with me because I wasnt following his post.
I now understand he was introducing "perimeter".
In a string of previous posts I had been thinking about volume and surface area.
If his post had started with something like; "Let’s consider the perimeter of two boxes"; maybe I would have understood.

Yes. Your statement was unclear to me. I now see that your post's equation described a method for definition of a conical surface.
Had no idea what your post 'was getting to' without further context. Thank you for reference to Fig 2-21.

No. The surface does not have a size just a defined slope.

No. I have not argued that a conical surface has size but that by Y14.5 definition a conical feature does have size.

Yes. A sloped surface is a major component of a conical feature however in the context of Y14.5 2009, a conical feature’s size can be prescribed by solid geometry. (base dia, axis, angle, apex or smaller truncating diameter)

Yes. A conical surface has no more size than a planar surface.

Yes. It is now more clear what reasoning is involved in your "equation question".
Without reasoning, your question would not be a coherent question relevant to subject matter.
I had no reason to believe you were not getting to some point of discussion.
Or was your question randomly incoherent? Which fits your question, coherent or incoherent?
No insult intended. Seriously trying to understand where you are coming from.


3DDave
I finally believe we are in agreement.
My suspicions regarding previous posts "by others" was that their post’s resistance to accept conical features as I-FOS was because of difficulty in quality inspection verification.
That appears to be the case at least from your post ?

I have never stated that inspection would not be challenging.

The point of my posts was to show that conical features are I-FOS by Y14.5 2009 definition.

Difficulties for inspection verification is a totally different discussion to me.

 

[Burunduk]

dtmbiz,
I don't think that they claim tapered features are not FOS because of technical inspection issues. I think there are two main arguments against tapers as FOS:

One is the assertion that tapered features are not FOS because geometrically, these features cannot arrest a contracting/expanding envelope representing the unrelated actual mating envelope. "Geometrically" means in a manner similar to, but less obvious than - a flat plane that cannot constrain translation in the direction parallel to it. Not a matter of inspection, but a matter of geometry.

The other argument is the absence of a single defining size that represents the entire tapered feature, which leads to an approach that says that size is not even a relevant characteristic - "all you need is an angle".

There is a reasonable amount of logic behind these assertions, but I am not in full agreement with them.

 

[3DDave]

dtmbiz - Not sure there is agreement. The standard does not say what it means to "contain or be contained by." Since a drawing is primarily an acceptance criteria document, an inability to properly inspect or make use of the inspection results makes it a non-starter.

 

[Burunduk]

There is no need for a definition of the obvious. Some terms should simply be understood literally - "contained" means one inside the other. A perfect form envelope closely surrounding an imperfect feature - good enough for any industry needs as it is.

 

[3DDave]

If I push a 120 degree cone sideways in a countersink it slides out. Is that contained?
If that surrounding countersink contracts, it forces the cone out. Is that contained?

If I push a bolt sideways in a hole it stops moving. That is contained.
If the hole contracts on a bolt, it clamps it. That is contained.

We are all "contained" on one side of some theoretical plane; that doesn't make a plane a feature of size.

 

[Burunduk]

3DDave,
Machine tapers are used to tightly secure cutting tools in tool holders or spindles, male cone inside a female cone. Isn't this containment?

 

[3DDave]

Push them the other way and they fall out. If those features were frictionless, and drawings, et al, do not depend on friction, they would fall out on their own.

 

[Burunduk]

Machine tapers work by the same physical principles that the definitions in Y14.5 are based on; a cylindrical feature specified as a primary datum feature constrains 4 degrees of freedom, a conical datum feature as a primary datum feature constrains the same 4 plus one additional translation. The cone could not be as constrained as the cylinder in the relevant DOF without being as "contained" by the simulator as the cylinder. Or perhaps you find para. 4.3, and fig. 4-3 in '2009 flawed too?

Speaking of machine tapers, below is a parametric drawing of 3 different conical shanks of the same type. The designations of the items are BT30, BT40, BT50. How would you describe the main difference between the three? Specifically, what do the numbers 30, 40, 50 tell you?

 

[dtmbiz]

If written text cannot be discussed relying on the premise that the words of the text are based on accepted definitions (dictionaries) for a particular language (in the case of ASME Y14.5 – English) then it is futile to attempt any meaningful discussion.

As in another referenced thread where Axym referenced the force “friction” regarding static containment of an AME, I completely disagree. The subject is not about “moving parts”, rather about static condition. The force involved is “normal”. That which prevents one solid from occupying the space of another.

This concept would not include continuous expansion or contraction (expanding or contracting) rather a static condition of “expanded” or “contracted” as the terms used in Y14.5. Actual Mating Envelope is just that, an envelope / wrapper. There is no more continuous force being applied than wrapping paper on a gift box.

The AME concept is not for immobilization as a result of a DRF nor the DOFs of constrained by each datum feature. As a matter of fact if enough force is applied lets say to a gage pin in a DRF then the gage pin would break. So what force is the accepted default force for a DRF before the addition of datum feature “restraint”” requirements?

The only “side” that I am aware of that Y14.5 references in terms of a diameter are, inside and outside. Not sure how to interpret “120 deg sideways” in reference to FOS.

The following equation defines a conical surface in a Cartesian coordinate system:
z = sqrt(x^2 + y^2) / 0.15
Note that the constant 0.15 is a pure number, not a length, and that it is the only constant involved.
Can you describe a conical surface which is smaller or larger than this one?

Lastly but not least, I suppose I just didn’t see the “elephant in the room” regarding pylfrm’s equation post regarding definition of a conical surface.
If variables “x” and “y” are assigned values in order to solve for “z”; the result is a single x,y,z coordinate in a Cartesian Coordinate space. A single point does not define a conical surface nor a conical feature. Yes, you “got me”.

 

[3DDave]

Every parametric geometry description is like that. Planes, cylinders, spheres, tori, cones, paraboloids, et al. The surfaces are those which pass through all points that satisfy their respective equations. These are the equations that CMMs use. The gotcha is that if a single number represents all conical surfaces of every extent then any other description is not of the cone but of the extent of the cone relative to some reference. It's why a single countersink tool can produce conical surfaces with different truncations, but the tool fits them all exactly; they are all the same.

A truncation of a cone, if it is at exactly right angles to the axis of the conical surface, can have a size; the conical surface has no innate size. The BT-series is cones truncated to different lengths where the diameter of the truncation is approximated by the series number. However if the cone angle was changed, one could still produce that same truncation diameter, so would those cones with different angles having the same truncation be identical in size?

Like I wrote, it's a can of worms that anyone is welcome to contaminate their own work with, but I'd rather see it sealed up and a fully developed paper written to support other cases and without redefining words to mean other things.

 

[Burunduk]

The force involved is “normal”. That which prevents one solid from occupying the space of another.

That is a good point, and I would add that the only type of force that has any relevance in a GD&T discussion is the normal force. It is relevant mostly to constraints of degrees of freedom. A common argument is that an unrelated AME can only exist if it can be "constrained" by the surface of the feature, otherwise the AME is ambiguous. I find nothing wrong with this argument as long as only the possibility of normal forces is considered. For that matter, I do not consider sliding, as in a conical envelope that "keeps contracting", a basis for rejecting a UAME. The envelope can as well stop contracting as soon as the slightest normal force is exerted, the mechanism that would allow it is irrelevant.
Another good point on the same matter:

This concept would not include continuous expansion or contraction (expanding or contracting) rather a static condition of “expanded” or “contracted” as the terms used in Y14.5

 

[Burunduk]

The BT-series is cones truncated to different lengths where the diameter of the truncation is approximated by the series number. However if the cone angle was changed, one could still produce that same truncation diameter, so would those cones with different angles having the same truncation be identical in size?

To be exact it is the base diameter which is approximated by the series number*. Regardless, the combination of a base diameter and the specific taper angle decides the size at any cross section at a given location from the base along the conical shaft. So the answer is no, cones with the same base diameter and different angles would not be identical in size. Is the size for a conical feature only defined in relation to a different feature? Not really. Given two cross sections along the conical feature at a known distance, if you know the nominal diameter at one cross section and the nominal angle, you will know the nominal size at the other cross section.

* It must be a very rough "approximation" for BT50, maybe it's the diameter at some gage length. Regardless the numbers in the designations indicate what the title of the column in the table says: "shank size". The fact that the size is not uniform doesn't mean that it's not size.

 

[dtmbiz]

3DDave

A cone with a specific base diameter (maximum size by tolerance) is overlaid by and positioned to another cone with a specific base diameter (minimum size by tolerance),
both have the same perfect surface angle (perfect as defined by Y14.5 via gage tolerances), and both have the same cone height.

You cant be saying that both cones would have the same size truncated diameter ? Are you ?

A truncation of a cone, if it is at exactly right angles to the axis of the conical surface, can have a size; the conical surface has no innate size. The BT-series is cones truncated to different lengths where the diameter of the truncation is approximated by the series number. However if the cone angle was changed, one could still produce that same truncation diameter, so would those cones with different angles having the same truncation be identical in size?

What about the BT-series having different size base diameters (d1) ?

Why would I want to change the angle which is the only constant varible shown in the BT-series in order to come up with an identical truncated diameter? That would be comparing "apples to oranges"

My idea of a Y14.5 conical feature inspection would be as defined by the first sentence of this post.
This would be to deterimine if the produced concial surface falls within the zone defined by the two prescribed cones.

We both definitely have different views on Y14.5 2009 conical features.