Surface Profile question

[[Cl...]]

I have a surface profile callout 6x equally spaced (60° circular pattern rotating around X) for each of the six features I'm recalling 3d curves into Free Form Surfaces. Since These profiles are not called back to any Datum, should I create an alignment for each one and allow rotation around X?

[[Ro...]]

Hi Clarke,
If it's a 6x pattern it needs to be best fit and evaluated as a group. You can evaluate each profile separately, but they need to be evaluated in the same best fit alignment.

If you're using curves, you could create a best fit alignment from curves, and select that in your profile evaluation of each curve/surface.

[[Cl...]]

Thanks Robert. Since these aren't called back to any datum, what about allowing rotation around X?

[[Ja...]]

You should allow for all degrees of freedom not just rotation in X.

[[Cl...]]

Just for rotation not translation, correct?

[[Ke...]]

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If the profile is not called out to any datum, then shouldn't all rotations & translations be free?
If there isn't another profile/location callout that evaluates the features when constrained to a datum, then the engineer may not have completely understood what they were putting on the print(?)
Is this for an internal customer, or an external customer?

[[Cl...]]

External (Medical device) Only a customer spec is called out on the print.

[[Cl...]]

I just found the spec. It is ISO 2768-2 Class Medium K. Calypso does not have as an option this spec.

[[Ro...]]

That ISO spec is a general tolerance document to control geometric tolerances on untoleranced features. It shouldn't apply to your profile if it's already toleranced in the drawing. If the profile doesn't have a tolerance then you would use that spec.

[[Ja...]]

If no datums are specified on profile callout, it just means that you are best fitting the nominal surface to the actual surface without any constraints.
Meaning your nominal surface should be free to rotate and translate in all axes so as to achieve that bestfit with lowest possible deviation.

[[Ch...]]

Since these are 6x pattern, you may want to use Geometry Best Fit, from Resources, Utilities menu, instead and allow rotation around the proper axis.

Similar to a pattern of holes and SIM REQTs : if you rotate individually, Calypso might rotate a lot to fit of your features, but in assembly - depending on the function, they wont be able to rotate this much individually, etc.

Then in your Profile characteristic - you would choose your Geometry Best Fit for all 6.

Good luck, and happy measuring !