Rand 3D Webcast Working with Legacy Datums in Creo Parametric 4.0+ Questions and Answers

June 1, 2020 Natasha Reaves

Thank you for attending my Creo Legacy Datums Webcast. If you missed the live webcast, you can view the recording here. https://resources.rand3d.com/creo-tips/rand-3d-webcast-working-with-legacy-datums-in-creo-parametric-4  
I had several questions asked during the webcast which I have answered below: 

Question 1: Is that "Create DFS option" new since Creo 5?

Answer to Question 1:

The Datum Feature Symbol command was introduced in Creo Parametric 4.0. In releases before Creo Parametric 4.0, a Set Datum was used.


Question 2: How many differences are there for Legacy Datums between Creo 3.0 and 4.0?

Answer to Question 2:

In Creo Parametric 3.0 (and earlier versions), a Set Datum was created as a property of a plane or axis feature. These referenced were either selected from existing references or created in the drawing.

In Creo Parametric 4.0 (and later versions), a Datum Feature Symbol is created as either a standalone annotation or inside of an annotation feature.


Question 3:

It appears you were able to add DFS to the model, why didn't you show annotations in the drawing?

Answer to Question 3:

Ideally, I would show the annotations in the drawing. What I wanted to demonstrate in the presentation is that you can add a datum feature symbol to the model or in the drawing.


Question 4:

If a DFS is created in Drawing mode, do they exist only in the drawing, or will it also exist in the model?  Does it matter which mode it's created in?

What are the impacts of not converting?

Answer to Question 4:

A DFS (datum feature symbol) created in Drawing mode exists only in the drawing; it will not exist in the model. If you want the flexibility of changing the references to affect both the model and the drawing, create the DFS in the model.

The impact of not converting to DFS in Creo 4.0 (and later versions) is that if you need to make changes to dimensions or geometric tolerances, you will first have to associate the dimension or geometric tolerance to model geometry, which is why we need to create a datum feature symbol. Also, the older method of using set datums is based off of outdated standards. You will be required to convert legacy datums to comply with the latest design standards.


Question 5:

In Creo 4.0 why would the rotate datum be grayed out?

Answer to Question 5:

If we are referring to the   Image1_rotate-text-position  button in the Additional Text group of the Datum Feature tab, you must enter text in the text field (make sure to hit <enter> key afterwards) in order for the button to highlight as shown.



Question 6:

How do you attach the DFS to a feature dimension in the model?

Answer to Question 6:

You just select the dimension to attach the DFS to. Once to select the dimension, you can move the frame to a desired location.


Question 7:

I'm new to Creo, why does it seem so difficult for such an easy operation?

Answer to Question 7:

A great question. I will say that as with most operations in Creo, there is a process. The process typically does not change much between versions. As the basic concepts are more important than the commands required to perform a task, in time you will be more comfortable with the process.


Question 8:

How do you get the dimension to show up?

Answer to Question 8:

I am not sure of the context, but you can show dimensions in the drawing using  Image8_Show-Model-Annot Show Annotations option.

And you can display dimension in the model tree by selecting  Image7_settings  (Settings) > Tree Filters > and check Annotations option. 


Question 9:

I think they was already stated but I wanted to confirm. If I am using an older drawing that uses ASME Y14.5 1994 per the drawing, will I have to use a CREO version prior to 4.0 in order to edit any of the datums or to create new GDT off of the legacy datums?

Answer to Question 9:

If you are using an older drawing that uses ASME Y14.5 1994 AND you need to edit this drawing in Creo 4.0 (or later version), you will need to open the model in the Creo 4.0 (or later version) and convert the existing set datums to datum feature symbol annotations. 


Question 10:

On a drawing I made recently, I got a duplicate datum name error.  But the way we do our drawings I need the ability to have datums A, B, and C in multiple parts shown on the same drawing in order for the tolerance notes to make sense.  Is that error message telling me that I have multiple datum C symbols on a particular part (which is something I don't want and thus is a useful error message) or is it warning me that I have multiple datum C symbols per drawing (and if that's the case is there a way to disable that warning?).

Answer to Question 10:

The following is the response from the attendee who asked the above question:

I figured out a work-around: by creating the DFS’s in the part instead of in the drawing (the key step I was missing was showing the dimension annotations in the part so that I could then select them when placing the DFS), I was able to create a separate datum C symbol on each part and then show them on the drawing annotations without it complaining.  So it does allow multiple datum C’s, one for each part, as desired.  My mistake was I expected incorrectly that when I created the datum feature symbol in the drawing attached to a part dimension that it would become a symbol associated with the part.  But it was associated with the drawing view, not the part, and thus CREO was somewhat justified in its complaint that I had two datum C’s because they were both tied to the drawing (in their respective views), not to the parts. 


Question 11:

In the newer style (Creo 4.0+), how are datum extension lines controlled/edited? They are currently displaying with a dashed line, and it needs to be a solid extension line.

Answer to Question 11:

This question will be addressed in an updated version of this blog.


Question 12:

Do the drawing mode options work if a combined state was used to create the drawing view?

Answer to Question 12:



Question 13:

I do not see my draft datum created in the drawing in the model tree under annotations. I am using CREO 4.0 is there a specific way for the draft datum to appear the model tree on the part? Or does that only appear for legacy datums and not ones created in 4.0?

Answer to Question 13:

Draft datums do not appear in the model tree or in the part. In Creo Parametric 4.0, if the Annotate tab is active, draft datums will appear in the Drawing Tree under the Datums area ( Image1_Draft area ). If the Annotate tab is not active, you will not see annotations in the tree, though they are visible on the drawing.

If you want datums do not appear in the model tree, create the datum in the model. Then later when you are in the drawing, you will see that datum in the model tree. And you will be able to show the datum in the drawing using the  Image8_Show-Model-Annot (Show Model Annotations) option.


Question 14: Can we step through an example of troubleshooting a set datum that is placed on a datum axis that is at an angle/normal to current orientation plane?

Answer to Question 14:

This question will be addressed in a future blog.




About the Author

Natasha Reaves

Technical Training Engineer<br><br>As a graduate of North Carolina Agricultural and Technical State University, she earned her Bachelor’s and Master’s degrees in Mechanical Engineering. After graduating, Natasha served as a mechanic in the U.S. Army National Guard and worked as a mechanical designer for a multinational telecommunications and data networking equipment manufacturer. Her love of CAD manifests at Rand 3D, where she enjoys teaching Creo Parametric and CATIA training classes. She holds certification from Dassault Systèmes as a CATIA V5 Expert Mechanical Designer and Certified Surface Design Associate.

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