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Runout includes profile?

Runout includes profile?

Runout includes profile?

(OP)
This is a two-pronged question for all of you regarding total runout...

First, I claim that total runout may be applied to a cone, IF the angle of the cone from the datum axis is given as a basic angle.

A colleague insists that it can't; his main evidence is that Y14.5 doesn't give an example of one (flimsy, eh?).  But I point to paragraph 9.4.2.1 (of 2009 std), which glaringly omits "cylindricity" from the list of other characteristics covered by total runout.  Thoughts?

Second, that same paragraph mentions "profile of a surface" as one characteristic that total runout may control.  We know that profile of a surface must be applied to a true profile (meaning a basic diameter), but I maintain that runout tolerancing is not meant to control size -- the diameter of the part should not be basic. Though the standard doesn't say this latter item, I infer it because they make no mention of the dial indicator being zeroed at a specific distance from the datum.  Thoughts?

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

RE: Runout includes profile?

J-P:

Either runout does not control size but circular runout controls a combination of roundness and coaxial while total runout controlling, in addition to circular runout, "straightness, angularity, taper and profile of a surface" per 6.7.1.2.2 in the 94 edition.

Yes, if the feature was tapered, the taper must be reflected in a basic dimension.  

Dave D.
www.qmsi.ca

RE: Runout includes profile?

Good luck measuring total runout on a taper.  I'd like to know how that goes.

RE: Runout includes profile?

(OP)
I don't see why it's any more difficult than checking total runout on a straight cylinder.

For a regular cylinder the dial indicator has to be rigged so that it travels parallel (0º) to the datum axis.

So for a taper, the dial indicator is rigged so that it travels at a prescribed angle (say 10º).  Either way, the angle of travel must be calibrated first!

But yes, both of these are more difficult than checking circular runout.

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

RE: Runout includes profile?

(OP)
Right Dave, but do you read that as saying that total runout controls size? (Since it mentions profile in the explanation.)
 

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

RE: Runout includes profile?

Total runout measures the total deflection over the entire length of a revolved surface.  A tapered surface will eat up a lot of that deflection just by the taper.  Effectively total runout contains a surface within a cylinder of a given thickness.

There is nothing in the definition of total runout that makes adjustment for the indicator deflection changing due to surface taper.

RE: Runout includes profile?

(OP)
But Tick -- I'm saying that "what if" the taper is given as a basic dimension?

If you say that it's not possible since the standard says nothing about a basic dimension, then I think paragraph 9.4.2.1 of 2009 should say that it controls cylindricity also. (It does say "taper" but I can control the taper even on a cone.)

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

RE: Runout includes profile?

J-P:

TheTick is correct when it comes to confirming total runout on a taper. Circular runout on a taper is easy using a divider head or chuck but total runout?? The only way is to use a machine chuck setting the tapered angle but that is not a measuring instrument. I know that there must be equipment out there that can do it but it would have to be a special purchase.

Figure 6-48 example explains the meaning of total runout and it is not about a true profile. It states "The feature must be within the specified limits of size.".  

Dave D.
www.qmsi.ca

RE: Runout includes profile?

(OP)
Thanks Dave.
I was right in thinking that runout does NOT encompass profile of a surface. ASME needs to revise paragraph 9.4.2.1.

But regarding inspection of total runout: we all agree that circular runout is easy (relatively). But are you saying that total runout even on a straight cylinder is difficult?

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

RE: Runout includes profile?

depending on the geometry,a taper can be checked for total runout. if it's a shaft it can be located between centers on top of a sin bar, tilted to the correct angle.
then the entire surface of the taper can be verified.

an other way would be to have a 4 th axis index head & that can turn & tilt to the correct angle.

RE: Runout includes profile?

(OP)
That's exactly what I was thinking.

If total runout has the indicator move along a rail parallel to the axis, what's the big deal about tilting the rail (or the part) to a prescribed angle?  The real question is whether the standard even allows a basic angle to be mentioned.

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

RE: Runout includes profile?

John-Paul,

Here's my take on it.

First, I would say that total runout can be applied to a cone.  Or a sphere, or any surface of revolution.  It would just be very difficult to inspect these shapes using a dial indicator method, because the indicator would have to be tracked normal to the feature's basic profile.  This requirement applies to circular runout as well, although it is often overlooked or ignored.

Second, the statement in Y14.5 that total runout can control profile of a surface is incorrect and should be removed.  A runout tolerance does not control the size of the feature.

There is another example in Y14.5 that muddies the waters even more.  See Figure 6-24 in '94 or Figure 8-18 in '09.  Before I begin my rant, what do you guys think of it?

Evan Janeshewski

Axymetrix Quality Engineering Inc.
www.axymetrix.ca

RE: Runout includes profile?

(OP)
Hmmm Evan,

I see what you're getting at.  That profile of a surface is not applied to a "true profile"  because of the +/- dim on the diameter.

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

RE: Runout includes profile?

John-Paul,

Yes, the diameter is plus/minus and not basic.  So the profile tolerance's usual control of the "magnitude" of the feature is overridden in this case.  Of all the things in Y14.5 that drive me nuts, this might be number one.  The profile tolerance ends up controlling the form, orientation, and location of the cone - everything but the size.  This is exactly what a total runout tolerance would do.  So why did they avoid using total runout on the cone, and choose to use a mutated profile instead?  To me this doesn't make sense, and is an example of Y14.5 being example-based and not rule-based.

Evan Janeshewski

Axymetrix Quality Engineering Inc.
www.axymetrix.ca

RE: Runout includes profile?

John,
I think it can too, The reference you stated says circularity and taper, I believe that is cylindricity, just like they say coaxiality not position or concentricity. They slipped in some generic terms. I asked this in another thread, isn't runout just an inspection method not really a functional requirement?

RE: Runout includes profile?

I have seen where a profile geometric tolerancing is specified, to control diameter, angle & so on.
in addition runout or total runout is also applied.
where that feature needs to more precise.

but it appears to me total runout is specified normally to parts that simply rotate & are not static.

RE: Runout includes profile?

run out & total runout (when perpendicularityis required) are very easy to verify on rotating shafts, gear shafts, & so on.  

RE: Runout includes profile?

This is why they love it so, it is easy, some here are worried we apply tolerances that are too complicated for the down stream,  I say this is the opposite case, it is easy for them but what does it mean to me, nothing. How much taper? How much eccentricity? How much roundness? This is what I need. When it doesn't pass then we have to sort it out.

RE: Runout includes profile?

The importance & cost of the product will dictate the quality required. GD&T is that tool to make sure the designers requirements are satisfied.

GD&T is not that difficult, once one is trained for it.
and if applied correctly it can improve you drawing.

back to the original post
runout is a seperate feature it should not be used to
control size of diameters.
It is one of the more easier attributes to check
& so is roundness, taper,cylindricity & true position.
I have done it all.

The one I dislike is profile of any surface. however
it can be easily checked with the right equipment.
if the manufacture doesn't have the right tools.
thats an other story.

 

RE: Runout includes profile?

"Runout doesn't control size". If the relative tolerance numbers are small to the size tolerance that is not really true. So to ignore it beacause it was not stated there is silly, they make general statements, these standards are not tablets from GOD.

RE: Runout includes profile?

Runout does not control size.  Simply picture a cylinder twice the diameter that it should be but perfectly straight.  Runout is in, size (and profile) are out.

RE: Runout includes profile?

Maybe it is too late in the day, but, if I have a diameter tolerance of and .005 a runout of .001, once you establish a number, it can only vary by .001, right? that is what I mean.

RE: Runout includes profile?

yes I agree my last staement should read can not instaead of should not control runout.

fsincox

that is correct diameter & runout seperate attributes.

however total runout can incorporate perpendicularity & taper depending on the feature.

RE: Runout includes profile?

sorry for the bad typing
bad on me :>/

RE: Runout includes profile?

(OP)
fsincox -- No, they are two different things.  You asked: "If I have a diameter tolerance of and .005 a runout of .001, once you establish a number, it can only vary by .001."

It's not problem if the diameter over a run of 50 parts varies by .005. But runout is asking if an individual part is consistent around its circumference.  So imagine making two shafts each with perfect runout (i.e., no wobble as it's checked with a dial indicator), yet their sizes (the distance across the center) might differ significantly.

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

RE: Runout includes profile?

(OP)
One other point -- I think when they say that total runout can control taper, that doesn't imply that it must be a straight cylinder.

If I call out a cone with a basic angle of 10º we can say taper is properly controlled if the actual part doesn't deviate from 10º.   

What I mean is that I don't read the phrase "controls taper" to be equivalent with the phrase "prevents taper."
 

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

RE: Runout includes profile?

Belanger

if a .001 total runout is specified on a flange face.
the face can not deviate more than .001 across the face.
is it not controlling perpendicular?

if a .001 total runout is specified on a cylindrical diameter
it can not deviate more than .001 across the length regardless of the diameter size.
is it not controlling taper?


Best Holidays to every one

Take Care

 

RE: Runout includes profile?

I am sorry, John, I just want to check one thing, if I have a part with a .500-.505 diameter size callout, and the surface is indicated total runout of .001  to a datum axis. This same diameter can measure .500 in one place and .505 in another? I think, I misunderstood runout.

RE: Runout includes profile?

(OP)
mfgenggear -- I would say yes it controls perpendicularity, and yes it controls taper.  My original post went further, and speculated that if a basic angle were given to describe an intended taper, then total runout could still be used to maintain the taper and keep it from deviating too far from that prescribed angle (just tilt the rail that the dial indicator rides on).

Fsincox -- No, the part you propose would not be legal, because of the runout tolerance.  But I think we were saying this: Just because a part passes a runout check (it might register zero deviation) that does not mean that the part is the correct size. Thus, runout does not control size.

You kind of said that already when you stated earlier (time=16:33) that "once you establish a number" in your scenario, but I goofed and missed that. You say that we will have "established a number," meaning that we verified the diameter some other way. The runout tolerance will then ensure that the rest of the part maintains that size, so I guess in that respect in has some influence on size.

Merry Xmas, all!

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

RE: Runout includes profile?

Fsincox

look at it this way.

The diameter would be inspected by means of a micrometer.
measurements would be taken 120 degrees apart or more.
the maximum & minimum are the variation in size.

The run out would be inspected by means of a dial indicator.
the part would be rotated on it's axis point , centers or diameters. the movement on the dial would be it's total run out. now verifying all the way across the length would be total run out.
if the diameter is at the low limit & it passes run out.
it's good.
if it's on the high limit of the diameter & it passes run out
it's good.

It is two independent verifications.

RE: Runout includes profile?

I agree with John-Paul, but I think I see what fsincox is trying to say.

Total runout does not control the size of the feature.  But one might say that, for a cylinder, total runout controls the range of local sizes that the feature can have.

Another way of looking at total runout is in terms of deviations from the basic profile.  The deviations do not have to have a certain value, but they must be consistent.

Evan Janeshewski

Axymetrix Quality Engineering Inc.
www.axymetrix.ca

RE: Runout includes profile?

Thanks, guys, I have started to respect your opinions enough, I was beginning to think I missed something. I realize the point I was trying to make is obscure, but, that in it self kind of helps make the point I was going for, namely a listing of the thing controlled by runout would not contain size yet it can in this case. Runout is not a size control tolerance, as many here have strove to point out to me, but it can have an effect on size tolerance variation in a part. I think the statement in the standard as referred to earlier is a general statement not an absolute.

RE: Runout includes profile?

Legality issues aside, why not just use runout and (if absolutely necessary) a straightness callout? Checking straightness can't be any more difficult than trying to move a dial indicator along a part at some oddball angle. I see no benefit to using total runout on a taper.

RE: Runout includes profile?

(OP)
I think because straightness can't be referenced to a datum, and thus it would not verify that the taper is at the correct angle.  Total runount -- with the mention of a basic angle -- does control the degree of taper.

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

RE: Runout includes profile?

Quote (Belanger):

I think because straightness can't be referenced to a datum, and thus it would not verify that the taper is at the correct angle.  Total runount -- with the mention of a basic angle -- does control the degree of taper.

Good point. Circular runout also provides such a control by constraining the position of each circular element of the taper to the datum within the allowable tolerance. A refinement could be made with concentricity if necessary (maybe the only good use of it).

Thing is, shops are set up to do TIR on a cylinder or a flat. I think you'd get some funny looks if you put it on a taper.

RE: Runout includes profile?

So in the final analysis can we now agree here that while total runout is not advertised as a size control, it will have that effect given the conditions I have stated above, the only thing restricting the size variation is the runout tolerance, what do you want to call it? The point being, that the standard in making those kinds of statements is generalizing and you must be actually looking at it from their perspective because it is not "literally" true.
Frank
 

RE: Runout includes profile?

To the OP, I do not see why cylindricity is not covered, bottom line.
Frank

RE: Runout includes profile?

(OP)
Frank -- total runout certainly CAN control cylindricity, but my point was that it is not a "must."

If the standard stated that total runout always "must" control cylindricity, then that symbol could never be used on a cone, which was the thrust of my OP.

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

RE: Runout includes profile?

John-Paul,
Thanks,
Frank

RE: Runout includes profile?

I am not an inspector nor do I play one on TV, but it does seem that if you could set it up at the basic angle you could, did you ever really get an agreement/consensus?
Frank
 

RE: Runout includes profile?

(OP)
Yes -- the general agreement was that even though the standard doesn't show such an example, total runout on a cone communicates a certain idea that is valid. (And the inspector at the meeting didn't have a problem with it!)
 

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

RE: Runout includes profile?

Thank you, John-Paul.
I recently have become the engineering rep. on my companies new GD&T committee. In that function, I saw that my company had a gotten a proposal from you for training. Say about a year ago, in the Northern Illinois area. I was disapointed as I recognized your name from here and would have enjoyed a chance to meet and talk with you in person.
Frank
 

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