Flatness on offset planes

[[Ma...]]

I have scanned 3 circle paths on 3 planes and one is offset so I made an offset plane but when I try to get flatness off of them it come out as perfect even thought the individual planes have some form deviation. Any thoughts?

[[Ch...]]

offset plane is theoretically perfect I believe.

 

 Just create regular plane from scans and check flatness before offsetting ?

[[Ma...]]

If I recall the feature points into plane the result is like 1.7 which I know isn't right and its called out as a continuous zone so they have to be evaluated as one plane. 

[[Ke...]]

If its a Flatness callout, but the planes are offset (are that offset by 1mm?), perhaps, you need to evaluate Profile of a Freeform Surface (with no Datums)? ...do you have Freeform on your CMM?

[[Ma...]]

Unfortunately not on the offline seat, our CMM is down for calibration this morning, they are offset by 11.3 mm and the other two are on the same level, I would think there would be an easier way to do it. 

[[Ke...]]

 

"How to Control Offset Planes

To design and inspect two offset, nominally parallel planes so they act as a single functional feature:

1. Use Basic Dimensions: Apply exact, untoleranced (basic) dimensions between the surfaces.
2. Apply Profile Tolerance: Attach a Profile of a Surface symbol (e.g., \bigcirc \mkern-5mu \vert{} \mkern-5mu \bigcirc with a value of 0.05 mm) to the Feature Control Frame (FCF) for both surfaces. This ensures both surfaces are held coplanar within the same tolerance zone GD&T Tips - For Coplanarity Use Profile - Tec-Ease. [1]
3. Add Datums as Needed: Depending on how the planes mate in an assembly, you can orient the profile zone relative to an established datum system, or leave it datainless for free-floating coplanarity"

"Common Mistakes to Avoid

• Using Flatness on Both: If you try to call out individual Flatness on two separate offset surfaces, each surface is evaluated indepenantly. The GD&T specification does not enforce that the two planes be co-planar, parallel, or at the correct basic offset to one another Flatness OR Profile ON Flat Surface. "

Edited June 8