Total runout
Total runout
(OP)
I have a question about total runout. My understanding is that total runout controls form, orientation and location, but not size. However, Section 9.4.2.1 of ASME Y14.5-2009 states that "Where applied to surfaces, constructed around a datum axis, total runout may be used ot control cumulative variations such as circularity, straightness, coaxiality, angularity, taper and profile of a surface." What confuses me is that this section says total runout controls profile of a surface. Doesn't profile of a surface control size?
Thanks
Thanks





RE: Total runout
I prefer to think of it this way: profile is actually one tier above runout, in terms of a GD&T hierarchy. Therefore, we can say that profile of a surface on a cylinder will control total runout, but I disagree when they say that total runout controls profile of a surface.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
Not true J-P. See fig. 8-26 in '09. And in the light of that figure runout seems to control true profile of a surface.
Although I agree with you that profile is one tier above runout
RE: Total runout
So while you're correct in terms of "the letter of the law," I stand by my statement because the runout itself is on a "floatable" diameter constrained by the 0.25 profile.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
RE: Total runout
Profile can be specified without datum and act in the way similar to flatness or cylindricity.
In this case it may be indirectly controlled by total runout.
RE: Total runout
Seems to me that in that figure, the profile tolerance of 0.25 is a basic accuracy requirement, i.e., the surface could be anywhere within the ±0.25 boundaries and could potentially vary within a given part by that much. So, one could imagine a profile that zigzags between those boundaries and still meet the profile tolerance. The runout requirement seems to say that wherever the profile starts in the profile boundaries for a given part, the profile cannot move by more than ±0.15 closer to either boundary, thereby actually controlling the shape of the profile.
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RE: Total runout
It's like saying that flatness on a surface controls parallelism. Sure, flatness controls ONE element of parallelism (form), but such a statement is an overreach.
IRstuff -- Yes, the figures are the same, and I would agree with your statements. Profile can trump runout, but runout doesn't trump profile.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
And it basically means that any circular cross-section cannot "wiggle" more than 0.15, while the entire profile may vary within 0.25
RE: Total runout
How profile inherently controls size if it lacks datum reference?
Ref Fig 8-8,page 163 of ASME 2009.
RE: Total runout
So for Fig. 8-8, ask yourself what the maximum length would be. The basic length is 60 mm, but with the profile wrapped around the part (actually, all over the part), then the maximum permissible length would be 60.6 mm (0.3 mm outward on all sides).
Notice that all of this has nothing to do with a datum; it's the same surface being toleranced everywhere.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
I was wondering, is it possible to "officially" email the ASME committee with questions and receive official responses? I'm just curious, because I am a new member to the group, and so no one will take my word for it, and also most of the older guys in the group wouldn't put any stock in anything on internet forums. So it'd be great to get an "official" answer to my question.
Either way, thanks everyone for the help!
RE: Total runout
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
We must intimate ASME committe regarding this statement written in 9.4.2.1 of ASME 2009.What do u think?
RE: Total runout
RE: Total runout
intimate that: He intimated that he intends to leave."
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RE: Total runout
RE: Total runout
What exactly is preventing us from using runout the same way?
RE: Total runout
At any rate, the paragraph in question (9.4.2.1) is talking about total runout, which is presumably applied to a cylinder, not a cone. Thus the diameter must be a basic dimension.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
Just look at Para. 8.4.4 Conicity"
"A profile tolerance may be specified to control the conicity of a surface in two ways: as an independent control of form as in fig. 8-17, or as combinations of size, form, orientation, and location, as in Fig. 8-18."
It's all right there in black and white: conicity, not cylindricity, two ways, one with controlling size and one without controlling size.
Denial much?
RE: Total runout
About Para. 9.4.2.1 "Applied to Surface Around an Axis."
It actually says: "Where applied to surfaces, constructed around a datum axis, total runout may be used ot control cumulative variations such as circularity, straightness, coaxiality, angularity, taper and profile of a surface."
Since when angularity and taper apply to cylinders?
Also, there is big picture there, Fig. 9-1 showing “surfaces constructed around the datum axis”.
There is a conical surface right in the middle of it.
So, if profile can be used to control angularity (not size) of conical surface, and total runout can be used to control angularity (not size) of conical surface, why under certain circumstances they cannot be used interchangeably?
RE: Total runout
When a blanket statement is made, such as "total runout controls profile of a surface," that is saying that every time total runout is applied, you get everything that profile of a surface would control in that same situation.
But that is simply not true for total runout. You can find all the specific cases you want where it might be true (well, just one: the cone without a datum surface), but that does not justify a blanket statement implying "in all cases."
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
I really don't think words "may be used" constitute blanket statement meaning "anyplace, anytime"
My very first post 3 days ago was: "The standard doesn’t say “runout controls all the possible cases of profile”."
My very last post said "under certain circumstances"
If somebody was making a blanket statement, it wasn't ASME Y14.5-2009, and it definitely wasn't me.
Sorry again.
RE: Total runout
I suppose the phrase "such as" is not meant to be an all-inclusive list. So I concur with your point that, under certain circumstances, they are the same.
It's just that 9.4.2.1 is a strange statement because profile of a surface is not covered by total runout, other than a rather unique situation (more to come...)
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
See the attached picture: it is my interpretation why -- when applied to a circular feature -- profile of a line/surface must be applied to a basic diameter.
First, the standard does say in paragraph 8.2 that profile is to be applied to a true (i.e., perfect) profile.
In the first picture on my graphic, no basic dim is shown because the basic dim is of course zero. But in the second, third, and fourth pictures, we should all agree that the radius needs to be basic. So why then, in the last picture, would it be OK to suddenly drop the basic dim and use a toleranced diameter? Answer: it isn't OK. And the cylinder idea that started this discussion is simply an extrusion of the last picture in my attachment.
The one exception I keep referring to is Fig. 8-17 of the standard. There the diameter can be toleranced, only because on a cone like that the profile tolerance "shell" can scoot left and right. In other words, we don't need a precise diameter to lock onto; you can move it back and forth to suit any diameter. Therefore the plus/minus tolerance on that diameter is OK.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
If we extend the same logic to “round” pieces we will see profile acting as roundness, runout (not controlling size) and “real” profile controlling pretty much everything.
In fact profile is so versatile, it’s probably impossible to make blanket statement about it.
To me Y14-5 simply means “you think profile, but sometimes runout may be good enough” (I said “sometimes”
RE: Total runout
Unfortunately don’t have enough time right now to come up with similar picture for round piece.
RE: Total runout
What we are supposed to be talking about is a situation where the profile wraps around the entire part, thus intersecting in some way with size.
So imagine if I added the all-around symbol to the middle picture on your graphic, CH. Would you say that the plus/minus tolerance on the height is OK?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
Very interesting thread, here's a quick response for now. Overall, I agree with J-P.
The statement (or intimation, anyway) that Total Runout can control variations in profile of a surface is, at best, very misleading. I wish that Y14.5 had not included this statement in the 2009 standard, and I will advocate removing it from the next revision.
Even though there may be special cases in which we can get a similar end result by using either Total Runout or Surface Profile, this does not mean that we should make this kind of statement. If we do, then by the same logic, we could also say that Flatness or Perpendicularity can control variations in profile of a surface.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Total runout
The radius isn’t. So using radius as transition from square to circle is “not kosher”.
I can imagine dimensioning everything in basic, say, for profile of a wing, or some other shape consisting of several “radii”. Features of size on the other hand are pretty much controlled by, well, size. So in many cases we only need geometry control as a refinement.
So I can imagine profile being used not to its full power, but in the way that allows some other geometry control to substitute it. (Not that there is something wrong either way)
RE: Total runout
This isn't about "features of size." It's about the shape of a part, and the dimensions defining that shape. So I don't care if it's a partial arc, or a full circle, or whatever shape; the rule is that a profile tolerance must be applied to a "true profile."
I think you are confusing dimensions that describe the shape of a part with size and location dimensions. (See the graphic I posted at 13:56 today.)
A couple of questions that might help here...
First, if I added the all-around symbol to the middle picture on your graphic, would you say that the plus/minus tolerance on the height is OK?
Second, if we're discussing a profile tolerance, what are the dimensions for the "true profile" for a flat slab and a round piece?
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
RE: Total runout
And earlier in that same paragraph, it states that profile is "used to define a tolerance zone...relative to a true profile."
Put those two statements together, and you'll have the gist of my posts today. It has nothing to do with datum references or tolerancing the distance from a datum; those are separate issues.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
Could you please explain in light of said paragraph, where is basic dimension in Fig. 8-14? Should they add “all around” symbol to it? Where is basic dimension in Fig. 8-27?
Using profile as refinement of toleranced dimensions – right there in the standard book.
Profile must always be accompanied by basic dimension – blanket statement, not really in the book.
Sorry.
RE: Total runout
I am not talking about the dimensions that relate the profiled surface back to a datum or to anything else. I am talking about the actual dimensions that define the shape itself. Please notice that this has nothing to do with a refinement of size or location. Rather, it has to do with the true profile -- the shape itself.
Therefore, the basic dims that define the shape in those figures you ask about are zero! (Again, I'll refer you to the graphic I posted yesterday at 13:56 -- that might explain it better.)
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
So, invisible dimensions? Two can play this game.
Look at the enclosed picture. Imagine that cylinder is actually a cone with basic angle of zero degrees (invisible). Can I use profile then? How this profile is different from total runout?
RE: Total runout
If we can get past that foundational concept, then we can gladly discuss a part is truly a cone (i.e., with a designed-in angle of taper).
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
I am also disappointed that you only see zero dimensions where it suits your case.
I can see this discussion turning into bickering and will gladly leave it where it is before things turn sour. We couldn’t convince each other – better luck next time.
RE: Total runout
I didn't see the discussion going south, but I'm also willing to let it go. Peace, out...
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
I was originally on JP's side on this, but I can see CH's reasoning as well. The problem is that the standard gives a mixed message with regards to what types of dimensions can be used in conjunction with Profile tolerances. I don't think we can say that one is right and the other is wrong - there is evidence to support both opinions.
Here are some thoughts on CH's latest figure with the Profile tolerance on the cylindrical surface with a directly toleranced diameter. Is this compliant with the standard? On the one hand, the true profile is not fully defined by basic dimensions which violates Paragraph 8.2. On the other hand, there are figures showing a Profile tolerance on a conical surface with a directly toleranced diameter. Applying this same idea to a cylinder is not a big leap. To me, the standard contradicts itself here. I would say that if you polled the Y14.5 subcommittee on whether or not CH's cylinder application is legal, the result would not be unanimous.
My personal opinion is that the true profile should always be fully defined using basic dimensions (this includes basic linear dimensions, basic angles, basic diameters and radii, etc.). This is the only path to a rigorous definition of the tolerance zone. I do not support the use of directly toleranced dimensions in conjunction with Profile tolerances, even though the standard still includes figures showing this. One reason is that these examples are non-rigorous and require certain assumptions to be made. The second reason is that these examples muddy the waters as to how a Profile tolerance zone works (resulting in many discussions like the one in this thread). In the examples involving Profile on a conical surface with a directly toleranced diameter, the form of the tolerance zone is theoretically exact but the size of the tolerance zone is not. This makes the Profile tolerance zone behave like a form tolerance or a Total Runout tolerance, but only for features that can have a directly toleranced dimension. There are no rules describing exactly how this works, only examples.
So I wish that the Y14.5 would make it clear that Profile tolerances must work in the way that J-P describes, but I acknowledge that the standard allows them to work in the way that CH describes. Y14.5 is trying to move forward with more sophisticated and rigorous Profile techniques, while not abandoning past practices involving simple geometry with directly toleranced dimensions. This is still a work in progress.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Total runout
Unfortunately the trend out there seems to be using profile for everything. It may have something to do with CMM becoming more affordable and widespread.
So if we have to loosen up some of our strict views, then we have to take it simpler: as long as we are able to figure out where the tolerance zone is, the control is legit – no matter profile or runout, or else. That was the point I was trying to make.
RE: Total runout
http://eng-tips.com/viewthread.cfm?qid=302470
Evan, as I see it (and ref. to the thread above for the blow-by-blow discussion) the only reason that a toleranced diameter is acceptable along with profile on a cone is that the profile tolerance can be adjusted back and forth, thus allowing it to conform to any diameter. This is true if no datum is referenced to locate the zone longitudinally.
Allow me to quote from DeanD3W, who posted this on 17 JUL 2011 (my emphasis added):
"Profile on a cylinder absolutely requires a basic diameter. Profile on a cone requires complete definition by basic dimensions, but if no datum features are referenced that definition may be only the basic included angle of the cone (since the tolerance zone is free to translate in the axial direction it effectively become variable in size). If translation in the axial direction is constrained by a referenced datum feature then a basic dimension to the cone's apex may complete the definition, or as an alternative, a basic diameter combined with a basic dimension to define the axial location of that diameter may be used."
But indeed, the ONE thing we can all agree on is that it would be helpful if the standard gave more direction on this whole aspect of profile.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
RE: Total runout
You are not alone out there! I am just choosing not to rehash old arguments that will only serve to add confusion and leave us all in the same place in the end. :)
Frank
RE: Total runout
J-P
You were looking for a thread where ± direct toleranced dimensions and profile combination has been discussed:
I think is this one
http://www.eng-tips.com/viewthread.cfm?qid=320954
You and Dean went back and forth about this issue.
If it's not the thread you are talking about, please disregard my post
RE: Total runout
A) With Direct tolerances, profile will lose size control, it will only control orientation and form.
B) With Basic Dimension, profile will control size,orientation and form.
Now the question arises that where to use basic dimensions and where to use direct tolerance.I think Standard has not specified anything like this but i have discussed with one of the expert.According to him:
"Direct tolerances really only work well for individual features of size. If the feature(s) in question ACT like features of size in their application, then dimension them as features of size (i.e. with direct tolerances), but if they ACT like surfaces (i.e. not features of size), then treat them like surfaces and use basic dimensions with profile tolerances.
Now, what do I mean by "Acting" like features of size? Well, does this feature with the plus/minus (direct) tolerances on it fit into a slot on the mating part, or does the mating part always bias this part to one side of this potential feature of size (therefore, NOT acting like a feature of size)"
What u guys think of that?
RE: Total runout
You are taking Mark Foster's statement out of context. He was talking about a rectangular part and about allaround profile+ basic dimensions (or ± direct tolernaced dimensions).
Here in this thread CH , J-P were talking about cylindrical surfaces, conical, --surfaces around an axis-- which IMHO is not the same thing.
You just take a statement from something and extrapolate in something else.
Sorry, I don't think that's the right thing to do.
Anyway, majority of the guys on this form are also on linkedin....so it's easier for them to see the context for the disscusion.
Just my 2 cents
RE: Total runout