Cannot Evaluate Profile

[[Ma...]]

I am having an issue measuring profiles of planes on a small part I'm measuring. (The profiles are with respect to 2 datums which are a plane and a cylinder.) The machine measures the datums and the planes on which the profiles are taken without any error message. But when I try to execute the profiles, I get an error message that reads: "Evaluation of characteristic not possible". Does anyone have an idea what could be causing this issue?

P.S. The error message gives no indication of the reason the characteristic cannot be evaluated.

[[Ja...]]

Max,

Can you show part of your design/print?

[[Ma...]]

It's private so I can't.

[[Ri...]]

Fill in your secondary datum as your tertiary datum as well, so it should be Datum A for Primary, Datum B for Secondary, and Datum B for Tertiary.

See if that works. Calypso tends to not like incomplete DRFs in Profile characteristics.

This may or may not be your problem, but I would start with that first.

[[Ma...]]

Yes- I just discovered in the CALYPSO online help that the DRF requires either 0 or 3 datums.

[[De...]]

It sounds like you need a third datum to lock your rotation. Unfortunately, if you are not using free form then Calypso needs a fully defined datum reference frame to evaluate profile.

As a test you can simply add the plane you are checking in as your third datum. If that works then this is the culprit. This works if you only have one feature called to those two datum features, however if you need to check more than one feature to the same two datum features you need to go a step further.

When I have this issue, and there is no datum for rotational clocking, I create an alignment using the two datum features that are called out.

I then select this alignment as my alignment in a geometry best fit alignment and select all features that are called to the two datum features since you need to account for the simultaneous requirement if they are called to the same datum features. The best fit alignment then needs to allow rotation around the axis that is unconstrained by the two datum features.

Finally I create a theoretical clocking feature that references the geometry best fit alignment.

This feature can then be used as your clocking feature in your profile characteristics to lock rotation while still allowing rotation to be best fit for all feature that simultaneous requirement applies to.

[[Ma...]]

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Actually I didn't need to create an alignment with the datums. I simply used my cylinder as the second and third datum on each of the three planes where I took the profile. It worked even though I have multiple features measured to the same datums.

[[To...]]

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Can you create a simple sketch that replicates your application?

[[Ma...]]

The problem has been solved.