Creo Drawing Datums issue

[yguo]

I just start to use Creo recently, and I've got an issue when I try to set the datum for detailing a GD@T drawing.

Following are my questions,

1) What is the best way to define datum in drawing?

I like to define datum with the toolbar in the drawing. It shall be quick in 2D. Someone say, it's better to build the datum first in 3D. I do not know why.

2) My current issue is

On a drawing, I used to define datum, A, B, C. One plane, and two cylinder holes as datum feature. For some reason, I deleted mark of datum B and C from the drawing. Now I want to re-add datum B but it does not allow it saying " same datum name exist". I check the 3D, there is an axis I built with a name B, in the last position of the tree. But I can not delete it. I can press the delete button.  It just stay there. 

And also, I went through the tree of drawing, I delete all the feature with name datum B. But still dose not work.

My estimation is maybe creo remember the B and C datum in its memory because I used to define it in drawing. Is this correct?

But How to fix this issue?

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[StephenW]

Try renaming in the axis. If it's used in a GD&T callout, you can't delete the datum.

Even though you are creating GD&T callouts in the drawing, it is likely adding those to the model (depending in your settings).

[vfleury · Accepted solution]

1. I place datums and rename/activate those in 3D but define my geometric tolerances in 2D. IMHO, it's more easy. And you can move your box in an actual box in 2D.

2. For your axis, in 3D, open properties and use the first button for deactivating.

Maybe a prompt will appear if you are using it in a geometric tolerance.

Then you can delete your axis.

[yguo]

Thank you. This fix all the issue I have with the datum.