Pattern of holes as reference and function of frame with profile in a special condition
Pattern of holes as reference and function of frame with profile in a special condition
(OP)
Hello everybody.
Please, I need your support regarding the sketch attached. It is a simplified drawing of a shroud of turbine. Only the main features are represented in the sketch. The aim of drawing is to supply information to machine a lobule located at 30° from hole “O” at opposite position ( section E-E). There is a fixture that locate the part 0,15 mm off center (in the angle indicated) in order to machine the internal lobule. The part is supplied with an initial internal diameter ranging from 237,65 to 237,70. The average wall thickness is around 1,45 mm. The origin reference center (B) is established by the three holes diameter 7 in the basic diameter of 282 mm.
In a practical way, the internal lobule is done moving the cutter to outside little by little until the thickness reaching near 1,3 mm thickness at position of section E-E. In fact it is done controlling the final thickness.
Doubts:
1- Why the reference B is written as B-B inside the frames?
2- What does it mean the frame identified with interrogation (?) in the sketch and what would be its function?
Thanks for any comments.
Roberto1brazil





RE: Pattern of holes as reference and function of frame with profile in a special condition
I also don't have a good answer for your question about that profile tolerance with CZ. All of those profile callouts seems incorrect since we shouldn't apply profile to a radius dimension; we should apply it to the surface. And to further complicate things, they have two composite profile tolerance frames also applied to the radii. Ugh.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
Question 1: I have never seen a multiple-feature datum with repeated letters. It is not discussed in Y14.5, so the interpretation is questionable. It might be an ISO thing, but I doubt it. Could they be pointing out that there are three holes that establish datum B - then why not three B's.
Question 2: I have no idea. It appears to be redundant and conflicts with the other feature control frames with profile.
Sorry I cannot offer more. Maybe others will chime-in.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
I am also bothered that there is no datum (axis) for "centering" the (3) 7mm holes relative to some other feature on the part - like maybe the OD of the ring.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
I agree with J-P that a radius cannot have profile - only a surface can. And the composite profile symbology with "F" appears to be misapplied as well. Can we assume the upper frame is the restrained tolerance and the lower frame is the larger Free-State tolerance.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
1. Meaning of the reference to B-B in the profile tolerance frames - ISO 5459:2011.
http://files.engineering.com/getfile.aspx?folder=d...
So with regard to this item the only thing that looks incorect in the sketch given by OP is '3X' note missing right next to datum feature B symbol.
EDIT: In cases like this, where datum feature symbol is associated with a geometric tolerance frame and the number of features constituting the datum feature is given above the tolerance frame, the '3X' note is not required.
I think the discussion on whether it functionally makes sense to reference pattern of features at RMB (using ASME terminology) or not is, at least for now, beyond the scope of this thread.
2. The meaning of CZ modifier in the profile 0,025 tolerance frame - ISO 1101:2012.
http://files.engineering.com/getfile.aspx?folder=2...
Per the latest version of ISO 11O1 standard, issued this year, the CZ modifier is no longer called "common zone" but "combined zone".
3. The composite profile tolerance frames associated with both basic radii - ISO 10579:2011.
http://files.engineering.com/getfile.aspx?folder=5...
The attached figure does not specifically show usage of profile tolerance, but if we imagine that the surface marked A is not a flat face but an arc, and the feature/surface B is not cylindrical but of a complex shape, profile of a surface tolerance could easily be used instead.
So technically these are not composite profile callouts (in ASME sense). They are just tolerance frames defining the same characteristic (profile of a surface) in different conditions of the part - restrained vs. free state - just like the flatness tolerance frame shown in section E-E. Although here I agree that the profile tolerance frames should not be associated with the radius dimensions but should be applied to surfaces.
RE: Pattern of holes as reference and function of frame with profile in a special condition
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
Yes, for sure you are the ISO guy. I do have one ISO vs Y14.5 question regarding the B-B symbology. The Y14.5 interpretation o fthe dash between letters is a multiple feature datum. Considering the interpretation from 5459 in your post, is the ISO symbology different for multiple feature datums? If not, how do you tell the difference between for example B-B and A-B?
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
I am not really sure I understand your questions.
The rule in ISO is that if datum is derived from a single datum feature, then it is always indicated by one datum letter in the tolerance frame referencing that datum. If datum is derived from more than one datum feature, then that is always indicated by A-B or B-B or A-B-C etc. Technically, in the datum pattern example from my previous post one could use five different datum feature symbols for each hole and then reference to all five, e.g. A-B-C-D-E, in the tolerance frame, and that would change nothing in terms of datum establishment (compared to A-A). But obviously this would not be the most efficient way of doing things.
RE: Pattern of holes as reference and function of frame with profile in a special condition
Let me try again. Given the info in your latest statement quoted above: considering the OP drawing which has the pattern of three holes specified as datum B (by attaching the foot to the FCF), why in the profile FCF wouldn't it say B-B-B for the three holes (one letter for each feature) instead of B-B?
Or.. given the ISO symbology in 5459, is B-B used to represent a pattern of features (holes in this case) as a datum no matter how many features are in the pattern?
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
Now it is perfectly clear to me what you asked for.
Per ISO GPS if a group of two or more features is assigned datum feature and the datum feature is represented by a single letter, say A, then the datum reference in the tolerance frame should be A-A regardless of the number of features constituting the datum feature. So if a group of 5 holes is datum feature A (as shown in the example from ISO 5459), the datum reference should still be A-A, not A-A-A-A-A.
RE: Pattern of holes as reference and function of frame with profile in a special condition
Thanks for being patient. To me this is another example of the "confusion" offered by ISO. So, one letter "A" in the datum feature symbol (square)is represented by "A-A" in the FCF. Really? Why not use one letter like Y14.5 and avoid the confusion? Oh well. Maybe over time the two standards will evolve into one, combining the best from each.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
I don't really have good answer to that question. To me it looks like they really wanted to distinguish between datums derived from a single feature and datums derived from multiple features, and that is why they came up with this method.
Perhaps this will dissapoint you even more, but at this point of time, in 2017, I firmly believe that unification of ASME and ISO standards is not going to happen, at least not in another half of century or so. I have access to some of the recent versions of the most important ISO GPS standards, like 8015, 1101, 14405, 1660, 2692, 5458, 5459 etc. I also have the draft of the next version of Y14.5. Both standards are getting more and more complex but the way the complexity is handled is very different and it does not look like there is even a trace of wish to find similar solutions.
RE: Pattern of holes as reference and function of frame with profile in a special condition
RE: Pattern of holes as reference and function of frame with profile in a special condition
RE: Pattern of holes as reference and function of frame with profile in a special condition
Thanks all a lot for your attention. The drawing came from France and so I believe that it was ISO. Sorry for don't mention it. I am really glad for all comments. I was without internet since yesterday, and only today I was able to read.
Best regards
Roberto
RE: Pattern of holes as reference and function of frame with profile in a special condition
Thanks for the window into the future. I was being hopeful more than realistic. However, begin pragmatic, but not pessimistic, the influence of the US in the global manufacturing arena is diminishing. I suspect over time - decades as you said - ISO may become more prevalent than it is now - maybe even superseding Y14.5 as the defacto world Standard. Who knows.
Of note: I was at a Y14.5 Committee meeting a few years ago. I never realized it, but the Standards committees are "staffed" by volunteers and their attendance is financed by the organizations that employ them - there are government labs and educational institutions too. It was noted by the Chairman - Bruce Wilson at that time - that some attendees would not be attending as their organizations were no longer be supporting their attendance. Maybe this is a sign of something more systemic. Also, less support might be why the time between revision releases is longer.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
ASME most likely pays for the LARGE room at venue the meetings are held and what ever amenities are needed - coffee, tea, donuts. At the meeting I was at there were over 50 persons sitting "behind" the U-shaped table layout that the Committee members were sitting at - a big projection screen was on the 4th side. This was a 3-day event. I noted too that many of the other Y14.XX Committees had smaller meeting rooms reserved - many of the Y14.5 members are on other related Committees.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
RE: Pattern of holes as reference and function of frame with profile in a special condition
I have no idea how the Linux crowd controls revision status if they do. Revision control is critical to effective Standards. This forum is a clearinghouse for clarity of interpretation of a "fixed in time " Standard. I cannot imagine the chaos with interpretation if the Y14.5 was continuously revised - like the operating systems you mentioned. There is a public review and comment period for each release of Y14.5. The Committee members are professionals and experts. So, we accept this "representative" as opposed to "democratic" form of revision control to contain confusion.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
There is no public feedback and no posting of interpretations that were argued in the meetings, making the 'public' portion not particularly public at all. Even though I participated in three previous Y14.x public reviews I was not notified of the latest version of Y14.5 until the comment period had passed, and only because someone in this forum mentioned it in passing; I'd think that would have been appropriate at the outset, but Committee members seemed uninterested in gathering information. In the past the comment period was so short and the time to get shipped was long enough that I would have to check the ASME website on a weekly basis for nearly a decade to catch the notice. This is unreasonable. When I last looked the organization was such that if I didn't already know there was a public-review-draft, I would not find it.
I agree to the professional, but suggest that 'expert' is not always the case. Experts would not leave as many areas unexplained in their standards and certainly would not let so many typos and incorrect results get to publication.
RE: Pattern of holes as reference and function of frame with profile in a special condition
Which meeting did you attend? I might have been in the 50-person "peanut gallery" behind the Y14.5 main table. If there were donuts, you were lucky - usually it's just coffee and tea. In the other committees, we have smaller rooms with just water and mints. I usually have to go down to the Y14.5 room and get coffee from there ;^).
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Pattern of holes as reference and function of frame with profile in a special condition
Yes, I totally agree the communication is one-way and "catch as catch can". Do you know how ASME notifies the public of the availability of Review and Comment releases? Are the 14.5 guys following an ASME policy for this or is it determined by committee charter (or some other reason)?
I did request and get a copy of the Review and Comment for 2009. I submitted many comments, all of which were responded to - most rejected but several were held for discussion - by who I am not sure.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
It was in Dayton OD in 2010. It was my first and only meeting. Were you attending meetings then?
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
The review notice is the minimum per the ASME process, which seems dedicated to making sure as few people know about the process as possible. They obviously don't see me as a customer or contributor, even though they incorporated several of my changes in the last version. My email hasn't changed. There is a review page: https://cstools.asme.org/csconnect/PublicReviewpag... I see no fillable PDF form for electronic submission purposes.
I see some are now free; it seems like it cost me $120 to get the 2009 draft. The irregular schedule is also a problem.
1966?
1973 (7 years)
1982 (9 years)
1994 (12 years)
2009 (15 years)
(2017 draft) (8 years, quite a surprise.)
RE: Pattern of holes as reference and function of frame with profile in a special condition
No. I saw no list.
Thanks for the link. Do you have to be a member to get to this page?
Your observations are enlightening. Seems ASME is way behind the digital times. Maybe they could use paragraph and figure numbers to sort/filer comments and let the public create the "thread" of comments for each.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
RE: Pattern of holes as reference and function of frame with profile in a special condition
I was at the Dayton 2010 meetings. Do you remember a presentation on zone-based definitions for runout tolerances? I did the second part, with the crazy-looking figures. At the time Y14.5 was looking at zone-based definitions for circular runout and total runout, as there were those who felt that the indicator-based definitions were too old school and needed to be modernized. I was part of a group put together to study it, and somehow got tasked with presenting the results. The reaction was basically "that's not wrong, but we hate it". It turns out that the concept of full indicator movement through 360-degree sweeps is about 50 times easier to describe and understand than the equivalent tolerance zone convolutions. So they stayed with the indicator-based definitions at that time (I see that this has since been revisited and there are zone-based definitions in the latest Y14.5 draft).
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Pattern of holes as reference and function of frame with profile in a special condition
Unfortunately I do not remember your presentation and I do not have my notes with me at work to review. I vaguely remember Don Day giving a presentation on something about castings using a tablet and stylus (real high tech at the time), and Al Neumann and son Scott discussing something with Datums, and Jim Meadows doing something with Position. I remember being overwhelmed by the whole experience of my first Committee meeting - of being in the same room with a bunch persons who "know" GDT - and being able to follow the presentation. I keep working on my boss to send me to another meeting - fingers crossed.
Certified Sr. GD&T Professional
RE: Pattern of holes as reference and function of frame with profile in a special condition
Evan, ( or anyone for that matter)
Do you know, by any chance, why in the draft total runout will have to control cylindricity and in 2009 was not such a requirement? Just curious, why the "door" to have total runout on a cone (with basic angle) has been closed?
As someone stated before, maybe because of the "delta" ( new modifier) ?
Do you have any "inside" /backstage details?
RE: Pattern of holes as reference and function of frame with profile in a special condition
http://www.eng-tips.com/viewthread.cfm?qid=315985
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
A constant zone at a basic angle to an axis is equal to a profile tolerance. All that changes in the 'size' of a cone is the distance along the axis from the theoretical cone point/vertex/apex to any other features on the part; it's why cones don't have a 'size.' Any value is just a local value and can be found if the nominal cone is extended far enough from the apex.
I know that for convenience there are alternate dimensioning methods that give the appearance of size, but they really are variations of controlling where the apex of the cone is.
If the cone is a primary interface then all the other features should have locations traceable to the apex; it would be trivial to add this to the standard as the interpretation for all cones with basic tapers.
This is in contrast to a cylinder which is the same nominal size no matter how far it is extended so that a size can be determined and a perpendicular surface which has no size at all.
Since profile of a surface relative to an axis is the same as the proposed total runout, there is no need to add the interpretation to total runout; one could show that a cone surface profile could be verified the same way as proposed for conical total runout and direct seekers of conical total runout to the profile of surface.
RE: Pattern of holes as reference and function of frame with profile in a special condition
I think that thread is still open; maybe we should be posting there for that discussion.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
Edit - threads close after a relatively short period; that one is 5 years old.
RE: Pattern of holes as reference and function of frame with profile in a special condition
You say that every cone can be reduced to a point and a taper -- that's not quite correct because that would be an infinitely long cone. You need to also designate a longitudinal start/stop distance from the vertex. And guess what: that creates a definite size control.
I'll try to create a sketch showing why profile must have a basic dimension. And yes, this would lead up to the proposed "dynamic profile" modifier in the draft version of Y14.5.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
The basic dimension is on the taper. The cuts are located relative to the taper. Viola. No size measurement required to verify the cone.
RE: Pattern of holes as reference and function of frame with profile in a special condition
Picture an infinite cone, starting at a perfect vertex. If I take a finite chunk from stations 10 mm to 20 mm, you're telling me that it will have the same diameter as a chunk taken from stations 20 mm to 30 mm? I don't think so.
But let's set that aside. I want to focus on why profile of a surface would be different from total runout. I'm away from my desk for a couple of days, but I'll provide an example to illustrate my point. If you have access to Y14.5's draft, check out dynamic profile. That was created because the current meaning of profile is non-dynamic (locked around a basic dimension). This is why Evan and I were always complaining about Figures
8-17 and8-18; they make sense in one line of thinking but conflict somewhat with the text's description of how profile is to be used.edit: I don't have a problem with Fig. 8-17 because it's not related to a datum. Thus the profile zone can move back and forth.
But Fig. 8-18 is a problem because the diameter is toleranced -- I'll follow up in a couple of days with my explanatory sketch.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
I don't have a copy because it doesn't seem important enough after I worked on 14.5, 14.41, and 14.43 and mostly got snubbed with 'already decided, not looking at it, can't give evidence for reason decision was made. Thx. Bye.'
Had it been mentioned early enough then I might have taken a shot, but finding out after the close; nope.
RE: Pattern of holes as reference and function of frame with profile in a special condition
Profile doesn't control size in many situations where it's not applied all around (such as in Figure 8-27). But with a cone, the profile naturally wraps around the part, thus controlling size. This brings up the question of whether the diameter of the cone needs to be a basic dimension.
See the attached graphic, which consists of several profile examples. Notice the first one is applied to a flat surface: we should all agree that the "true profile" of that surface is simply zero (no curvature; that's simply a basic dim of zero). Then the second example shows a slight radius, and we should all agree that the radius must be basic.
More examples show the radius gradually wrapping around further -- and again we say that the radius is a basic dimension. When we get to the last picture we have a full circle (or cone) and doesn't it follow that the diameter should be basic?
This is why profile is different than total runout. To say that profile and runout on a cone are equivalent is to say that the diameter in my last graphic can be converted to a ± tolerance. And if that were true, then each of my previous sketches should also be allowed a ± tolerance, but the logic breaks down somewhere in that line of thinking.
The only exception to the idea of having profile on a basic diameter is Figure 8-17. There, it's perfectly fine that the diameter is given a ± tolerance because the profile zone is not related to a longitudinal datum, and can slide left/right to accommodate the size wherever it happens to be.
We'll have to see what happens with the new idea of "dynamic profile," but I suspect it will help overcome this conflict by allowing a profile zone to expand/contract.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Pattern of holes as reference and function of frame with profile in a special condition
Here's one question - can a nominally 1.0 inch diameter rod fit into a nominally 0.5 inch hole regardless of length?
I'd say that it probably cannot.
Next question - can a 15 degree taper cone fit into a 15 degree tapered hole?
I'd say it can if the distances to their extents from the apexes of the two features have overlapping ranges, a claim that is true without measuring any local size.
Since a cone is defined by the taper, working to convert it to other coordinates that hide that fact simply confuse that size is irrelevant.
RE: Pattern of holes as reference and function of frame with profile in a special condition
To get to the root question, should a profile tolerance be applied to a basic diameter or not? If not, then I'll be asking you about the first several pix in my previous attachment.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems