Positional tolerance of features in a circular array at tangency 1

[jszymkowski]

Looking for some suggestions...
I am having difficulty defining the positional tolerance of features in a circular array. In the attached illustration (first angle projection), the tangent point of each bump to the red diameter must lie in a tolerance zone defined by two cylinders 0.2 apart centered on datum axis A. I need to define this using ISO GPS rules.

Indicating the measured points must be taken at a tangency, seems to be the roadblock for me, but perhaps there is a better way to define this.

 

[3DDave]

How about using a note? Every symbol in the standard is described that way.

 

[mkcski]

I am not ISO GPS literate, so don't know if similar controls exist: But given Y14.5 conventions, you might consider using non-standard feature-of-size concepts. The "tips" define a circumscribed material boundary. And as 3DDave said, you might need some notes too.

Certified Sr. GD&T Professional

 

[jszymkowski]

Thank you, everyone. Notes are probably the way to go here if there are no specific ISO or ASME descriptors that could describe this.

 

[pylfrm]

jszymkowski,

Although I think I know what you mean, the way you've described the goal isn't entirely clear. On a real part, the bumps won't all be tangent to a single cylinder with a given diameter. I assume you actually want to control the point farthest from datum axis A on each bump; correct me if I'm wrong here.

Regardless, you may find some useful insights in the following thread:

thread1103-432346​

pylfrm