Spherical vs diametrical tolerance zone 2

The location in that DRF is a point so the tolerance must be spherical. It is located at the intersection of an axis and a plane that is offset from a datum plane.

Using a diameter symbol would leave the zone ambiguous.

Thanks Dave.
Makes sense. For my easy understanding one can say, that spheres must be controlled by spherical position. No exceptions

Wuzhee,
There is no rule saying spheres must be controlled with spherical position. Just like there is no rule saying cylindrical features must be controlled with cylindrical position.

Functionally, it probably makes sense most time but it's not always.

Side note: On your drawing, if datum feature B is the flat surface, I would recommend moving the datum feature B symbol away from the dimension line of the basic 9 dimension.

A should probably be aligned and B should not.

Since no limit on the departure from the point is given for the sphere, it's a spherical zone.

Without the reference to the zone would be diametral
With only a reference to the zone would be a width parallel to

pmarc said:

Side note: On your drawing, if datum feature B is the flat surface, I would recommend moving the datum feature B symbol away from the dimension line of the basic 9 dimension.

Click to expand...

You're damn right. I worked too much on this drawing my eyes just ignored it.
I know I'm wrong on my sphere only statement, I just made it easier for me. It will not be my most common positional tolerancing method assuming the number of spheres I make every year (probably less than 5)

3DDave said:

A should probably be aligned and B should not.

Click to expand...

You suggest switching datums, so A will be the plane and B the axis?

It is about the alignment of the dimension to the datum symbol and indicating a feature of size or not.

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AlternateL:

A circular runout to [A] could represent that the ball needs to seal as it turns and not deform the seal as it turns.
A position control to sets the depth control.

Not sure what software you are using to measure the feature, but I get callouts like that alot.

As Dave said, without that B secondary datum it is only diametrical as distance in Z is not required.

Many times you will need a clocking tertiary datum feature at your discretion to use in order to get many softwares to be able to create a X and Y plane. I use datums features that make sense to the machinists/setup and I output deviation in xyz so they can make offsets.