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Real-world application of ALL OVER profile tolerance

Real-world application of ALL OVER profile tolerance

Real-world application of ALL OVER profile tolerance

(OP)
The concept of an ALL OVER profile tolerance is easy to understand in cookie cutter examples, but I'm very interested to learn how the forum membership has used and seen this tool in the real world.

From the 2009 standard, 8.3.1.6:

"A profile tolerance may be applied all over the 3 dimensional profile of a part unless otherwise specified."

As always, the phrase "unless otherwise specified" is problematic. Specified how?

Let's consider a cube, fully defined with basic dimensions, with an ALL OVER profile tolerance. If I apply a refining, tighter profile tolerance or flatness tolerance to a single face of the cube, is it no longer located/oriented relative to all the other faces?

It would be easy to say that the ALL OVER tolerance still applies to all surfaces and the single face in question must simply meet both tolerances...however, what if I desire to allow one face of the cube to vary by more than the ALL OVER tolerance? Meeting both tolerances becomes meaningless, then. Furthermore, if the more generous tolerance qualifies as "otherwise specified", and the ALL OVER tolerance is trumped, is the face in question no longer located/oriented relative to the other faces at all?

Must the part be fully defined with basic dimensions, no +/- allowed? This is a much-debated topic itself, +/- dimensions and a profile tolerance applied to a closed outline...profile not controlling size.

In theory, the ALL OVER profile tolerance is a powerful tool...perfect for a part with some very complex aesthetic or ergonomic surfaces, but also a handful of more conventional features that must be controlled differently.

Is this a gray area with open interpretation or am I missing something?

RE: Real-world application of ALL OVER profile tolerance

The post looks a bit troll-ish, but I bite.

Quote (Nescius)

the phrase "unless otherwise specified" is problematic. Specified how?

Specified in unambiguous way according to standard(s).

Quote (Nescius)

If I apply a refining, tighter profile tolerance or flatness tolerance to a single face of the cube, is it no longer located/oriented relative to all the other faces?

Tolerances like flatness and other form controls DO NOT locate/orient anything, so nothing bad will happen.

Quote (Nescius)

if the more generous tolerance qualifies as "otherwise specified", and the ALL OVER tolerance is trumped, is the face in question no longer located/oriented relative to the other faces at all?

The face in question is located/oriented relative to the other faces according to control that YOU apply to it. It it YOUR responsibility to apply proper control when you override default setting.

Quote (Nescius)

Must the part be fully defined with basic dimensions, no +/- allowed? This is a much-debated topic itself, +/- dimensions and a profile tolerance applied to a closed outline...profile not controlling size.

Too many questions in one. Profile may be applied different ways, being combined with basic and toleranced dimensions, and every application will have different meaning. It is YOUR responsibility to keep application meaningful. GD&T is a tool, very much like a hammer. If you hit your finger instead of a nail, it is not hammer's fault.

And by the way - profile controls size quite well, if applied properly.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

(OP)
Rest assured, I have much better things to do, both at work and at home, than troll any forum...let alone a GD&T forum.neutral Quite frankly, I cannot tell if you're being deliberately obtuse in your reply.

The heart of the matter is this: What does it take to meet the burden of "otherwise specified" in the case of an all over profile tolerance? Read my questions again with this in mind. Of course, flatness does not control location or orientation...but if an all over profile tolerance can be nullified by applying a flatness tolerance to a single face, location and orientation control of that face is lost.

Is it the case that any control exerted on any feature, separate from the all over profile tolerance applied to the entire part, completely nullifies all control provided by the all over profile tolerance, in the case of that feature? If yes, then so be it. If I don't want it to work this way, there's nothing stopping me from spelling it out in plain english.

I'm merely seeking the experience of others...how have they used, seen, or interpreted the all-over profile tolerance. I have never seen even a single example "in the wild", only cookie cutter examples to explain the meaning of the callout, nothing about how it fits into an overall tolerancing strategy.





RE: Real-world application of ALL OVER profile tolerance

Unfortunately for both of us things like “default”, “specified otherwise”, “direct”, “indirect”, "refine", etc. are really poorly defined in the world of ASME. (See, for example, http://www.eng-tips.com/viewthread.cfm?qid=410353)

Other than that I am standing behind my words. Very often on this forum people are asking for some sort of magical solution that will automatically cover everything (all-around?) and not require thinking.

My answer is always "no" - If you think something is unclear, it is your job to clarify it.

You have casting with the hole machined in it. Surface of casting may be specified "all around", hole maybe specified "otherwise". Control applied to one single feature does not cancel out general requirements for the entire part. How exactly? There are hundreds of possibilities. Show us your case. If you ask overly generalized question, you get overly generalized answer.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

(OP)
Some thoughts:

I'm not wanting a magic solution, just trying to use the GD&T as it is written in the standard to its fullest extent. I didn't invent the notion of an all over profile tolerance. It's there in the standard, a very powerful tool that looks to the future. Read on...It's not as if part geometry is more complex than it has been in the past...a caveman carving an idol can create geometry that's unreasonable to define on a traditional paper drawing. What has changed is our ability to make and measure very complex geometry very accurately.

See the attached pdf for an example part. Instead of a decorative door knocker, imagine that the complex geometry was a custom prosthetic or a scaffold to grow human tissue or whatever futuristic application you can imagine. You'll never fully define the part with a drawing alone. The manufactured part might be totally specified, made, and checked with nothing but 3D scanned data.

So, rather than use the all over profile tolerance as some sort of cheat or shortcut, I'm wanting to see instances where the power of this tool was used well.

In my attached example, if I apply any tolerances in addition to the all over profile tolerance, I can make the argument that something has been "otherwise specified" and that the all over tolerance does not apply AT ALL to the feature in question. Other arrangements would be required to define the relationship between this feature and all the others...the ones still under the umbrella of the all over tolerance because they have not been "otherwise specified".

I believe the inclusion of the phrase "unless otherwise specified" in the description of an all-over profile tolerance is a poor choice. The all AROUND profile tolerance doesn't appear to have this same caveat. When I place geometric tolerances on drawing, it is for a reason. When "unless otherwise specified" is introduced, interpretation of the drawing quickly becomes a horrible, fuzzy flow-chart of what-ifs and if-thens...especially when the "unless otherwise specified" is baked right into the callout, according to the standard. Yuck.

RE: Real-world application of ALL OVER profile tolerance

OK, we are getting closer to something.

Here is the way I see it. This isn't "lion", more like a cube from your example, with flatness applied to one side of it.

Since flatness cannot restrict orientation or location, flatness tolerance zone is allowed to "float" within all-over tolerance zone.

If we had profile instead of flatness, situation could be different. Profile without datum references would be more like form control, while profile with datum references would be completely different animal.
I am sure in this case opinions about interpretation will differ between different experts.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

NESCIUS:

I want to weigh-in on this discussion in one area. Your statement "Let's consider a cube, fully defined with basic dimensions, with an ALL OVER profile tolerance. If I apply a refining, tighter profile tolerance or flatness tolerance to a single face of the cube, is it no longer located/oriented relative to all the other faces?" is not correct to my understanding.

As a side-bar: the 2009 Standard "suggests" that an ALL OVER profile be added to all drawings to guarantee all surfaces have geometric control – see paragraphs 2.11 and A.4.1. This allows "boundaries" to be determined, which is the current focus of the evolving approach to product definition taken by the Y14.5 Committee. The addition of the datum-specific terms RMB, MMB and LMB and the numerous "envelopes" are manifestations of the "boundaries" concept. Given this, I assume the ALL OVER profile is applied as a “worst case boundary” and refinements – based on function and fit-up - have a “tighter” tolerance than the ALL OVER profile.

The ALL OVER statement is a replacement for the default directive: "if not specified in the field or notes, go to the title block for the tolerance" typically applied to engineering drawings; except that ALL OVER profile offers much more control over the part features than most title blocks present (usually just size and angles). The ALL OVER profile indirectly controls the size and form of individual features, and the orientation and location between related features.

The root of your discussion is: how does the all-inclusive ALL OVER profile interact with “otherwise specified” refinements. In your cube example, flatness on the single face is a refinement of the form for that individual feature "offered" by the ALL OVER profile. So adding the flatness form control to the individual feature overrides the form tolerance from the ALL OVER profile; however, it does not override the orientation or location relationship between the cube faces "offered" by the ALL OVER profile. Additionally, if you make one side a datum and another feature perpendicular or parallel to it, the orientation relationship from ALL OVER profile would be refined by the specified orientation tolerance.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

Quote:

The 2009 Standard "suggests" that an ALL OVER profile be added to all drawings to guarantee all surfaces have geometric control – see paragraphs 2.11 and A.4.1.

I'm not sure how you read that suggestion within those two paragraphs smile

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

RE: Real-world application of ALL OVER profile tolerance

John-Paul:

I attended a Y14.5 Committee meeting right after 2009 was released. At the event several of the Committee members (D. Day , A. Neumann, A. Anderson. A Krulikowski) gave seminars explaining the changes to the various sections. One focus was the calcification of "boundaries" - these are my paraphrased words and not statements from the presenters. Since then I have read materials published by the same Committee members and they have the default ALL OVER profile in their examples. So yes, it is pushing things a bit, but technically it makes lot of sense. There have been recent posts about how "bogus" title block tolerances are at covering "unless otherwise specified" dimensions and how they do not provide adequate default geometric control. The ALL OVER profile is much better at default conditions.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

(OP)

Quote (mkcski)

I want to weigh-in on this discussion in one area. Your statement "Let's consider a cube, fully defined with basic dimensions, with an ALL OVER profile tolerance. If I apply a refining, tighter profile tolerance or flatness tolerance to a single face of the cube, is it no longer located/oriented relative to all the other faces?" is not correct to my understanding.

Yes, it sure would be clunky if this were the case. I do agree that in the case of the cube, a refinement of a specific aspect could coexist with the all over tolerance. It works seamlessly; overlapping geometric tolerances coexist all the time, perhaps even within a single feature control frame. That's pretty much what a composite profile tolerance is...several overlapping requirements, all of which must be met. The sticking point is "unless otherwise specified". What is it? Are there degrees of it? Fully otherwise specified? Incidentally otherwise specified? Ha!

RE: Real-world application of ALL OVER profile tolerance

Nescius:

I understand your post and agree. The interaction/interface between the default ALL OVER tolerance zone(s) and the tolerance zones from specified refinements is not defined anywhere that I am aware of. Clarity with ALL OVER might be easy for a cube, and would be very difficult for a part with more complex geometry - most are more complex than a cube, hahaha. But... a default ALL OVER profile stands a much better chance of defining unspecified geometry (boundaries)than a generic +/- title block.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

Nescius:

On another related note: ALL OVER profile dovetails nicely with the expanding use of 3D CAD part models and CMM machines (gantry, articulating arm, laser tracking, etc.) The BASIC (perfect) shape from the 3D model is loaded into the CMM software. The part is scanned (probed) and the point-cloud placed "over" the perfect model. Deviations are noted - I think the report it called a "whiskers" plot. This exactly mimics the ALL OVER profile. We use this technique with rough-castings to confirm adequate stock for machining.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

There aren't many examples in the Y14.5 standard (as well as in other Y14 standards) showing application of the all over profile tolerance in combination with other geometric controls, but I think fig. 4-43 in Y14.5-2009, although not showing all over profile application directly, may be useful to solve the dillemma.

In that figure there is a general profile of a surface callout |prof|0.8|A|B|C| applied to all surfaces unless otherwise specified. If the figure showed no other geometric controls than that general profile callout, I think we would agree that this general profile requirement would act as a all over control, right? However, since there are additional geometric requirements specified on the drawing, these requirements simply nullify the general profile callout for features controlled by the additonal callouts. It must be like this, otherwise for example the datum feature B would have to somehow magically meet the general profile requirement AND the 19+/-0.2 width requirement AND the perpendicularity callout. Otherwise the dia. 3.1 holes would have to meet the general profile requirement AND their size requirement AND the position callouts. This is definitely not how this drawing should be read/interpreted.

Now, if we apply the same logic to a simple cube controlled by UOS all over profile tolerance and having a flatness callout (regardless of its value) applied to one of the faces, the conclusion must be that the flatness tolerance nullifies the all over profile tolerance on this single face, meaning that the face becomes not fully defined (in terms of orientation and location relative to other faces of the cube).

In my opinion there is a simple way to eliminate the confusion. If someone wants to have the all over profile callout applied to all six faces with additional flatness callout acting just as a form refinement of one of the faces, the UOS term should not be used in conjuction with the all over profile callout at all. The all over profile callout without extra notation will well suffice.

RE: Real-world application of ALL OVER profile tolerance

I have a question to pmarc:

Let say, we have requirement for part to be primed and painted Red "all-over"

Then, there is "otherwise" requirement to paint certain spot White.

Does "White" requirement nullify "prime" requirement?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

Not able to tell, because you did not tell how exactly the drawing notes look like.

Assuming the requirement is to have (1) the entire part primed and (2) the part painted red everywhere except for a certain spot that needs to be painted white, the dilemma can be easily solved by using following notes:
1. PRIME THE ENTIRE PART.
2. PAINT THE PART RED EXCEPT CERTAIN AREA SHALL BE PAINTED WHITE.
So without using words "unless", "all over" and "otherwise" everything is clearly defined.

If however, for some reason, you really want to use those words, the notes could look like this:
1. PRIME THE PART ALL OVER.
2. UNLESS OTHERWISE SPECIFIED PAINT THE PART RED.
In addition to that there would have to be a local note specifying that certain area shall be painted white.

Does that answer your question?

RE: Real-world application of ALL OVER profile tolerance

Actually, no.

Take your second version.

According to your own logic, as soon as you specify certain area to be painted differently, it immediately nullifies EVERYTHING specified "all-over" for that area.

Or not?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

No, it does not nullify EVERYTHING specified for that area. It nullifies only that characteristic of area that has been specified in the UNLESS OTHERWISE SPECIFIED note. So in this case it nullifies painting red, but not priming.

Going back to the cube example, the flatness callout applied to a single face nullifies everything that has been specified in the UNLESS OTHERWISE SPECIFIED requirement for that face, which means it nullifies profile all over requirement for that face.

RE: Real-world application of ALL OVER profile tolerance

OK, I am getting your point (not like I am agreeing with it).

The words UNLESS OTHERWISE SPECIFIED have that magical quality,that any added requirement immediately nullifies the default one.

So, if certain requirement can be specified without magic words, it will not be nullified?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

I already tried to explain that for the cube the all over profile tolerance will still control the sixth face (the one with flatness refinement) if the UOS notation is not used in conjunction with the all over profile requirement. It is that simple.

RE: Real-world application of ALL OVER profile tolerance

Any solid standard reference to back it up?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

The lack of a Standard (definition) is exactly why you two guys are having this extend discussion. And, seriously, is really thought provoking and valuable. I will be paying more attention to these "global" conditions and how exceptions to them are interpreted.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

The most solid thing that could ever be used - logic (not like I am saying you are not thinking logically) winky smile

But seriously, do you really believe that in fig. 4-43 the UOS profile requirement is not nullified in case of all those features controlled by additional geometric callouts?

RE: Real-world application of ALL OVER profile tolerance

mkcski,

In the thread CH referred to in this discussion (see one of his previous posts) I said: "in my opinion one of the most important takeaways from it [the entire discussion] is that the UOS notes must be used wisely. It is not that they should not be used at all. In some cases they can do really great job, but sometimes they may get us into serious unexpected troubles."

RE: Real-world application of ALL OVER profile tolerance

Pmarc:

Thanks for refreshing me and I totally agree.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

I am just trying to find the best place to draw the fine line.

To me UOS means "if local requirement contradicts default requirement, the local requirement takes precedence".
If UOS is Ra128 and local is Ra63, then yes, indeed, local spot shall have better surface.

The gray area starts when there is no contradiction. It is possible to have Profile .05 all-over and Flatness .02 someplace (that still satisfies Profile .05)

Same with indirect requirement. Size may control many things, but it doesn't mean they are all explicitly applied.

This is why logic is not enough.

To me, when there is a possibility of misinterpretation, it's designer responsibility to specify, where UOS will be nullified, like "All-over this side of parting line" or "All-over as-cast surface"

At least, this could be less ambiguous.

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

My thinking is: I prefer to use the word "refinement" (of the default) as opposed to nullifying it, because the (global) default requirement is always in effect.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

That's basically in-line with my thinking: If requirements collide heads-on, you pick one of them. Otherwise (no pun intended) it's refinement.

Unfortunately "refinement" is defined in the standard as well as UOS smile

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

Checkerhater:

The phrases UOS and USO, and the word refinement are used frequently in the 2009 Standard. But I have not seen a specific definitions. Please clarify.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

That's exactly what I mean - no definition for both. (also for “default”, “direct”, “indirect”, etc.)

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

My bad. I missed your Smilee Face

I checked and they are missing in the DRAFT of the next release. Oh well

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

For what it's worth, here is another quote from another related discussion http://www.eng-tips.com/viewthread.cfm?qid=409569:

Quote (pmarc)

This is taken from the new draft of Y14.5, but I am more than sure that I saw this also in one of the other, already published, ASME Y14 series standards (I think it was Y14.41, but it would be great if someone could confirm):
"1.4.9 Unless Otherwise Specified (UOS)
The phrase "unless otherwise specified" or UOS is used to indicate a default requirement. The phrase is used when the default is a generally applied requirement and an exception may be provided by another document or requirement."

Are we now going to discuss what exactly "exception" means for each particular dimensioning and tolerancing scenario? winky smile

RE: Real-world application of ALL OVER profile tolerance

Quote (pmarc)

the default is a generally applied requirement and an exception may be provided by another document or requirement

If default is Profile, is Flatness exception or refinement?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

I believe that if you /replace/ the profile callout with flatness, you've lessened the definition of the part. That feature may no longer be otherwise located. Thus I think REFINEMENT would the more logical treatment. Though I think this conversation has exceeded practical application, it's kind of interesting.

I hate "unless otherwise specified" PROFILE FCFs as notes (or worse... just writing "profile .020 applies u.o.s.") more than I appreciate their efficiency. It seems to be overwhelmingly used as a crutch or C.Y.A. rather than to convey the design requirements.

RE: Real-world application of ALL OVER profile tolerance

(OP)
For parts where I work, I would prefer that an all over profile tolerance simply apply. Period. Any additional tolerances must ALSO be met. Overlapping, but not conflicting, not UOS. My parts are usually very small, an overall aesthetic shape with a handful of functional features. The tolerancing strategy is usually simple enough that I can "see" the downstream interaction between the all over tolerance and the others. If there are features that I don't want the all over tolerance to apply to, I simply use a note under the all over FCF.

Since the standard says:

"A profile tolerance may be applied all over the 3 dimensional profile of a part unless otherwise specified."

One could argue that UOS applies by default. How would you all feel about a note, "All over tolerance shall apply regardless of other tolerances.", under the FCF to negate the (possibly) default UOS nature of the all over control?

RE: Real-world application of ALL OVER profile tolerance

Nescius,

The company I work for has switched from detailed fabrication drawings, to Model Based Definition (MBD). We prepare a drawing, but it does not have dimensions. We have a note on the drawing that unless otherwise specified, everything is to be fabricated to a 0.4 profile WRT the specified datums. I hate MBD, however, this is an application of an all-over profile tolerance.

If the standard all-over tolerance is not suitable, we apply tighter tolerances to critical features either with new profiles, other GD&T FCFs, or by applying feature-of-size dimensions and tolerances.

--
JHG

RE: Real-world application of ALL OVER profile tolerance

(OP)
Thanks, drawoh.

I'm not experienced in MBD at all, but I can see why you hate it...drawings with no dimensions. sad I'm trying to make use of the all over profile tolerance, but the drawings I'm using it on have all the dimensions needed to check all the tolerances I apply. The only exception is the all over tolerance; you'd need the solid model to check that.

RE: Real-world application of ALL OVER profile tolerance

Nescius,

MBD is an issue separate from all-over profile tolerance. What is wrong with applying a set of basic dimensions completely describing the part, applying datums, and providing a note that states that, unless otherwise specified, everything must be made to a profile of 0.8mm?

--
JHG

RE: Real-world application of ALL OVER profile tolerance

Quote (CH)

If default is Profile, is Flatness exception or refinement?
Regardless of both tolerance values, flatness is exception to default profile. I am not sure what the word "refinement" has to do with it.


Quote (Nescius)

How would you all feel about a note, "All over tolerance shall apply regardless of other tolerances.", under the FCF to negate the (possibly) default UOS nature of the all over control?
I will say this for the third time in this post winky smile. Simply attach the all over profile callout to any feature of your part and do not use notation "UOS" or "UNLESS OTHERWISE SPECIFIED" at all. Then apply as many additional geometric callouts as you need and you are done.

If you are still afraid that it might be misinterpreted, your idea ("All over tolerance shall apply regardless of other tolerances.") should work fine. The other way of saying pretty much the same thing could be: "This tolerance applies in addition to all other tolerances".

RE: Real-world application of ALL OVER profile tolerance

(OP)
Thanks, pmarc.

Quote (drawoh)

What is wrong with applying a set of basic dimensions completely describing the part, applying datums, and providing a note that states that, unless otherwise specified, everything must be made to a profile of 0.8mm?

Of course, nothing would be wrong with this, assuming UOS doesn't cause confusion. The only caveat is that some geometry is deceptively difficult to describe on a traditional drawing.

In my case, some of this difficult-to-describe geometry actually needs to be actively and thoughtfully controlled. The features I'm controlling are aesthetic details on a type of consumer good where "fit and finish" is highly scrutinized. It's a subjective distinction, but I'm using the all over tolerance in a more active sense, as opposed to a failsafe.

Often, the most difficult choice I face when tolerancing a part is trying to determine how round, straight, flat, or symmetrical something needs to be in order to look good.

RE: Real-world application of ALL OVER profile tolerance

You probably would be better off by pointing at the surfaces to be controlled with a note that says manufactured part shall deviate from the mathematically defined surface as supplied in a STEP file relative to certain datums by no more than a certain amount.

One could also discard the datums if the part is a completely free item, such as a hand-held device that mates with no other parts and has no particular orientation or location needs.

The creeping definition of Profile to include things that aren't 2D projections is apparently an end run that muddies the conventional use of Profile.

Aesthetics isn't one of the variables directly controlled by Y14.5. For that you need to specify things like - surface variations in terms of deviations from ideal curvature, which are more noticeable than displacements from ideal form.

Tougher are conditions where two parts meet and it doesn't matter much what the variation is, but the relation between the two parts does matter, basically requiring the tooling of the multiple parts to be coordinated in some way.

RE: Real-world application of ALL OVER profile tolerance

Interesting discussion. And I have a real-world application which came up recently, so let me bounce the attached graphic off of everyone...

The form of the cut-out is very important between W-X and Y-Z (the sharp radii). The form of the remaining surface is less important. And the location of the entire cutout is to be held within .010.

Is that being accomplished? Or does anyone (ahem, CH) think that the location between W-X and Y-Z is uncontrolled?

John-Paul Belanger

RE: Real-world application of ALL OVER profile tolerance

Hard to imagine there's a reason for that sort of control; the smaller segments have available to them the full .010 variation from section to section in lumpiness; only discrete depths are constrained, but not against planar rotation.

If that represents a real design limitation, OK. Nothing missing or self-contradictory with this part.

RE: Real-world application of ALL OVER profile tolerance

Don't see anything wrong with the part.

I guess Belanger has mistaken me with someone else. smile

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

RE: Real-world application of ALL OVER profile tolerance

Apologies if I mis-read your earlier posts, CH. When discussing the cube with all-over profile, I thought you wrote that a flatness tolerance on one face would nullify the profile's entire duties for that face. Whereas I disagree: flatness would refine the form of that face, but profile would still control the orientation/location.
Thus the analogy to my situation.

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

RE: Real-world application of ALL OVER profile tolerance

There seems to be something that everyone is overlooking with the profile being "refined". The shape of the profile is defined by BASIC dims and the tolerance zone "follows" it no matter what width of the zone. So as you go "around" (along) the profile tolerance changes from a default ALL OVER zone to a wider or narrower refined zone - as in John-Pauls' sketch. This is true even with a "refined" flatness tolerance. The flatness must lie within the larger default ALL OVER zone. But now I am thinking: what happens if the flatness tolerance is larger than the default profile tolerance? Is it even logical to consider this for a design standpoint. I think not.



Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

So did we reach any consensus on UOS all over profile interpretation? To me J-P's example just supports the "theory" that when an all over (or all around) profile callout without UOS is used, the callout applies in addition to any other callout specified on the drawing.

RE: Real-world application of ALL OVER profile tolerance

pmarc:

I am not sure we have consensus, but I agree with your statement if: by "in addition" I assume you mean the additions are "refinements" of the UOS profile tolerance?

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

(OP)
pmarc,

I, for one, do agree. I started this thread because I'm not sure why "unless otherwise specified" is in this sentence in 8.3.1.6:

"A profile tolerance may be applied all over the 3 dimensional profile of a part unless otherwise specified."

I don't like the wording of that sentence, and I was afraid that UOS was an unspoken/default characteristic of the all over tolerance. Does the sentence mean...

"A profile tolerance may [only] be applied all over the 3 dimensional profile of a part [in an] unless otherwise specified [mode of operation]."

or...

"A profile tolerance may be applied all over the 3 dimensional profile of a part unless [the part is] otherwise specified."

I know, I'm off the deep end. conehead


RE: Real-world application of ALL OVER profile tolerance

mkcski,
Yes, the additional callouts must not be in conflict with the all over/all around callout. I am just not sure why you used the UOS term in conjuction with the profile tolerance winky smile That is not what I said.

RE: Real-world application of ALL OVER profile tolerance

pmarc:

I did not use the best choice of words. Let me try again.

I assume that whenever an ALL OVER profile is applied, it effectively becomes the "UOS" criteria and overrides anything in the title block or other document (J-P used the word nullify in his Oct 7 post). Adding other GDT controls can only refine the "default" ALL OVER profile.

Certified Sr. GD&T Professional

RE: Real-world application of ALL OVER profile tolerance

Hmmm...

Not sure how to comment on your last reply, mkcski, so allow me to put it this way. (I am afraid I can't be any clearer than this).

I will use J-P's example:

Case #1 - as is - all-around profile is specified WITHOUT extra 'UOS' note.
In this case profile of a surface controls entire contour all around and profile of a line controls line elements of the contour in zones W-X and Y-Z. In other words, profile of a line does not nullify all-around profile of a surface requirement in zones W-X and Y-Z. But this also means that profile of a line tolerance value can never be greater than profile of a surface tolerance value, otherwise there is a conflict. Just like there is a conflict when someone applies, for example, flatness tolerance of .010 to a surface that is already controlled by parallelism tolerance of .005.

Case #2 - all-around profile is specified WITH extra 'UOS' note.
In this case all-around profile of a surface applies only in zones X-Y and Z-W. It does not apply in zones W-X and Y-Z, because in these zones it is nullified by profile of a line requirement. This results in following:
1. Profile of a line tolerance can be of any value except .010.
2. 3D size and form of the contour in zones W-X and Z-W becomes totally uncontrolled. Additionally, orientation and location of the contour in zones W-X and Z-W relative to referenced datums is uncontrolled too. That is why some additional controls would be required to make the entire contour fully defined.

Does that clarify how I understand the 'UOS all-around/all-over profile' concept and how I see the difference between 'all-around/all-over' and 'UOS all-around/all-over' requirements?

RE: Real-world application of ALL OVER profile tolerance

One correction to my last reply:

Quote (pmarc)

Case #2 - all-around profile is specified WITH extra 'UOS' note.
In this case all-around profile of a surface applies only in zones X-Y and Z-W. It does not apply in zones W-X and Y-Z, because in these zones it is nullified by profile of a line requirement. This results in following:
1. Profile of a line tolerance can be of any value except .010.
2. 3D size and form of the contour in zones W-X and Z-W becomes totally uncontrolled. Additionally, orientation and location of the contour in zones W-X and Z-W relative to referenced datums is uncontrolled too. That is why some additional controls would be required to make the entire contour fully defined.

RE: Real-world application of ALL OVER profile tolerance

pmarc:

Sorry for the delay getting back to you - very busy today.

This is embarrassing, but following the posts I did not "see" the two cases and did not make a distinction between them. Sorry for wasting your time trying to get your point across to me.

Our drawings do NOT have a UOS note. By default our UOS condition is a "+/- and angles" title block - no default ALL OVER profile or any other GDT. So, I was not cognizant of the subtle difference between the two cases that you so clearly described. I think I agree with both. But bet me think about this and get back to the forum.

Certified Sr. GD&T Professional

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