Question about circular runout

[SteelAndSteel]

Hi,

First of all i am using ISO. I have noticed that the meaning of circular runouts change if the arrow is not pendicular to the surface, can someone explain that to me?

My main question is that i want to put a tolerance to the cone below (the thing which are brown)

http://s11.postimg.org/a7kc6jolv/image.jpg

Could i use this option
A circular runout to add a tolerance for every circular slize, then i add straightness so the angle of the cone stays intact

or is there a more commen way to do this?

http://s11.postimg.org/a7kc6jolv/image.jpg

 

[3DDave]

J-P,

You're easily correct. I tend to disagree with those with disagreeable usernames.

The '94 standard spends a lot of ink to say:

When a surface is formed by revolving a profile that is co-planar with an axis of revolution, runout is the range of variation in surface radius at any point along that profile as measured perpendicular to a tangent to the profile at that point when the part is rotated about that axis. Total runout is a measure of runout variation for all points on the profile.


Just to kick the '94 ASME Y14.5 committee, the figures are, per the Standard, only to illustrate what is defined in the text. Since they didn't bother to define runout in the text, it isn't clear that the runout related figures are correct or representative of all interpretations.

The committee applying angularity to an axis as a position control when the position control already controls the same thing is amusing. They could have gone all in and declared that, since you can tilt a part and use a dial indicator to measure angularity, just call that FIM and voila, it's runout of a flat item. Which it really is, assuming the axis of rotation is just an infinite distance away. And since you can guide the dial indicator along any path, all measures that can be done with a dial indicator could be runout.

 

[Belanger]

On closer inspection, yes the 1994 standard showed the dial indicator normal to the surface in the pictures, but you're right Dave -- they didn't really define such in the text. The 2009 edition corrects that blip by adding such a statement in para. 9.4.2.

As for this idea about what it truly means to be normal to the part surface, I recall a detailed discussion of this a long time ago. See the following thread, and maybe start reading at the posts beginning on November 24:

http://eng-tips.com/viewthread.cfm?qid=310831

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

 

[CheckerHater]

pmarc, could you elaborate on angularity being measured normal to datum?

 

[pmarc]

Where did I say anything about angularity being measured normal to datum on your illustration?

Dial indicator for angularity check needs to be oriented to datum axis through basic angular dimension. If drawing of this part is not showing basic angle, inspector won't be able to identify the angle between the dial indicator and the datum axis properly.

 

[CheckerHater]

My bad, I guess it looked that way at first glance.
Your nit picking rises interesting question (I think it was discussed before in some form):
We assume that "true geometric shape of a feature" is the one defined with basic dimensions, while runout can be applied to features of size as well. In this case indicator is set perpendicular to what? (Even more interesting in ISO when angle is a size)