How to measure sphericity on Hexagon PC-DMIS

[SM_19]

I am looking to measure how uniform a sphere is on my CMM. How do I do this?

Thanks

[SingularitY]

Use the circularity dimension.

[Schlag]

Circularity is 2D only

[SingularitY]

Good thing I've never ran into this yet! I've read In here before that it could be used for spheres also.
I take it the Form dimension is under the location tool?

[tking]

Form.

[Douglas]

Form (Rn) in the location tolerance for a circle does not return the same result as circularity using Y14.5, is there a little more that could clarify that?

[AndersI]

Rn in the location dimension depends on what mathematics you used when measuring the circle, probably LEAST SQUARES. Circularity does another best fit of the hits (CHEBYSHEV), as the standard dictates (at least ISO does, I'm not that well versed in ASME).

[dph51]

What tKing said.

[tking]

Thanks, dph51

[SingularitY]

From the PC-Dmis help menu..

The Insert | Dimension | Circularity menu option determines the roundness of a circle, sphericity of a sphere or the conicity of a cone. This dimension type is considered one sided, meaning a single positive value tolerance is applied.

[Douglas]

will the result be the same as Rn within the location tolerance for a sphere?

[SingularitY]

I would have to do some testing to find out. I'm curious.

[Douglas]

me too I've noticed the slight difference on circles but was always unsure why, either way our engineering does not use GD&T much at all I add them as I see fit to kick out of round parts back, so either works well enough for me but always been curious... Probably Andersl has it dead on above

[Fradders]

https://www.pcdmisforum.com/forum/pc...ing-sphericity

[BKulpa]

Profile, form only?