Runout to check positional location

[prdave00]

Quick question as a sanity check...

I have a tube with the OD as Datum A and position of the ID controlled by .002" RFS. Let's assume for the sake of this question that the OD and ID are of perfect form. Our supplier is saying they use circular runout to verify the positional tolerance is met and claim that since the runout is less than half the positional tolerance, these parts should meet print. Is that a fair assessment?

Fortunately they are bringing a CCM online so they can actually verify conformance to the positional tolerance, so this matter of using runout when I specify position only needs to be tolerated long enough to get some sample parts.

 

[dgallup]

As run out is a composite measurement of both position and form, the position has to be as good or better than the run out.

 

[Belanger]

Actually, there's no need to have it be half; the runout reading could be up to .002 and still be good.



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

 

[dingy2]

If the ID has a diametrical tolerance zone of .002, it does means that the feature is allowed to radially shift no more than .001.

A diametrical tolerance zone of .002 equates to a circular runout of .002.

Dave D.

http://www.qmsi.ca