Total Runout on a Cone 3

[Belanger]

I suspect this topic has been covered here before, but I'll toss it out there again.
Does anyone have a problem with total runout applied to a tapered cylinder? I claim that it's OK, as long as the angle of taper relative to the datum axis is given as a basic dimension.
Some folks try to say that it's not allowed since it's not in the standard, but this forum has discussed how the standard gives basic principles but can't show every possibility.
May be fodder for Y14.5-Next.

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

http://www.gdtseminars.com

 

[CheckerHater]

Good!
But "indicator on defined guideway(s)" is exactly how you will measure Total runout, isn't it?

 

[MechNorth]

As far as measurements go, yup, they're the same. I don't have an issue with that, other than perhaps runout is redundant or rather something of a special case of profile.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com

 

[CheckerHater]

Good.
Let me explain the idea in finer detail.
If you are to control Angularity, you will slide your indicator along guideway representing the angle.
Enter 14.5-09 Para 9.4.2.1: "When applied to surfaces, constructed around a datum axis, total runout may be used to control cumulative variations such as circularity, straightness, coaxiality, angularity, taper, and profile of a surface"
It's right there, total runout indirectly controls angularity. Only for angularity your indicator is touching fixed part, for runout - rotating one. Is there a way to specify angularity without basic angle?
Not to mention that total runout indirectly controls profile as well, so hierarchically it is standing on the higher level, isn't it?

 

[MechNorth]

When I read that section yesterday, that jumped out at me, so I was a bit (?) more flexible in my answer then. I think that angulatity on a rotating part is still ok, but there would need to be a basic angle invoked or you would have a dispute between a tapered tol zone & a constant-thickness conical one.
I don't see that runout would be above profile; is the inverse not also true, that profile applied to a revolved surface gives you total runout, angularity, circularity, straightness, coaxiality, taper?
The new (?) definition of total runout seems to make it synonymous with profile of a surface for a continuous surface of revolution (i.e. no interruptions). I think that it falls down when you have multiple (interrupted) surfaces unless a Continuous Feature is invoked. For Hierarchy, however, I look also at which one does more; runout controls can't be applied to non-revolved surfaces whereas profile controls can. That makes profile somewhat more robust overall with the exception of using it on directly size-toleranced (+/-) features.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com

 

[CheckerHater]

I won't argue that profile has more power (where profile is applicable).
Now, if we specify both runout and circularity, will circularity be refinement of runout? I guess that's the idea of one control indirectly controlling the other, and that was my idea of "hierarchy".
This is why i wouldn't go as far as calling runout "special case of profile". One is one, the other is the other.

 

[axym]

I agree that inspecting a surface of revolution for Surface Profile or Total Runout would involve exactly the same setup:
-If an indicator was used, it would have to be tracked along the basic profile. The only difference would be that the Surface Profile measurement would involve an absolute reading and the Total Runout measurement would involve a FIM reading.
-If a point-based coordinate metrology technique was used, the tolerance zones would both be based on the basic profile. The only difference would be that the Surface Profile zone would remain fixed at the basic profile and the Total Runout zone would be allowed to offset away from the basic profile.

So is Total Runout really a special case of Surface Profile? I would say no, that Total Runout is a distinct characteristic, and that the distinction should be made clear. But the standard really muddies the waters on this. It allows the mixing of Surface Profile with directly toleranced dimensions in certain special cases, giving a result equivalent to Total Runout. As CH quoted, it also states in 9.4.2.1 that "total runout may be used to control cumulative variations such as circularity ... and profile of a surface". This statement is extremely misleading at best, and if we're honest with ourselves it's wrong. If applied to a basically defined profile, Total Runout does not control Profile of a Surface. I agree with CH, Surface Profile has more power. Surface Profile can indirectly control Total Runout, but Total Runout cannot indirectly control Surface Profile. This is because the Total Runout tolerance zone has an extra degree of freedom (offsetting) that the Surface Profile tolerance zone does not have. Or, in the indicator world, it's FIM versus an absolute reading.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

[CheckerHater]

I guess they meant it in arithmetical sense.
If your surface profile is .10 off and the whole contraption is .20 eccentric, then total runout will measure .30 (in theoretically correct perfect world).
But like it or not, it will make profile refinement of runout.

 

[MechNorth]

OK, the lights came on re the floating zone. Sorry, it's been a dim couple of days.

Still don't see profile as a refinement of runout though.

I guide students towards the use of profile for cones (with basic dimensions). One reason is that it controls size as well as everything else, in one inspection setup rather than multiple. If a linear tolerance is applied for size or angle, it needs to be verified independently of surface location wrt datums, form, etc. I've used conical tapers extensively for almost 20 years, and based on the functionality profile eliminates the issues of separate size & location & form. I won't argue that there aren't conical applications that won't benefit from separate treatment, but I haven't experienced them yet.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com

 

[fsincox]

J-P,
Reading through Groeg Henzold's book: He refers to runout for "any other direction" (other than perpendicular or parallel) and it's application is specifically shown applied to a cone.
Frank

 

[Belanger]

For total runout?

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

http://www.gdtseminars.com

 

[fsincox]

J-P,
Yes, it discusses it for both types of runout. Even though it is an ISO text, it does indicate to me others must agree with the concept of it.
Frank

 

[Belanger]

Thanks, Frank. I've always thought the idea was sound, but too many people think that since it isn't explicitly in ASME that it isn't allowed.

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

http://www.gdtseminars.com

 

[dingy2]

I will put my 2 cents on this topic.

I can see total runout on a cone but it would be difficult to measure using conventional equipment. One would still place the part in a chuck but instead of having the travel of the dial indicator parallel to the axis, it would travel on the angle given. It would not control the location of the angle though. The total runout would be the TIR or FIM of the indicator full length of the cone. This would probably apply on small cylindrical features or cones that can be chucked. I think that it would be a bad day for someone in Quality trying to confirm this requirement and I would love to see the measuring equipment.

Profile of a surface on a cone would control size, angle and variations in the surface probably using a CMM. One could fail this requirement just through location of the angle alone. All cone related dimensions would be basic.

Dave D.

http://www.qmsi.ca

 

[fsincox]

J-P,
this one is for you. This is my first attempt at uploading and basically a test.
Frank

 

[Belanger]

Thanks, Frank! He should probably have shown a basic angle there, but it's a good example to get the idea across.

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

http://www.gdtseminars.com

 

[fsincox]

That is in the text on next page, I think:
"However, during the checking of total runout in any directon, the positions of the dial indicator are along the guiding line (theoretically exact generator line of the toleranced feature) parallel to the theoretically exact position with respect to datum axis B."
I think TED is how they refer to basic?
Frank

 

[Belanger]

yep.

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

http://www.gdtseminars.com