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Datum Target Points in Merged Model

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Datum Target Points in Merged Model

I'm working in CREO 4 and I have a casting model with datum target points defined in it and then I have an external merge setup for the machining model. I need to reference the datum target points from the casting model to establish my machining datums but I can't find out how to get these target points and datums to show.

 

Please help.

13 REPLIES 13
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Re: Datum Target Points in Merged Model

Assuming you have "point display" checked, when you regenerate the merge part the datum points should display.

Also check if the points are associated with a hidden layer.

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Re: Datum Target Points in Merged Model

That works to show the points but is there anyway to carry over the datum annotation feature and datums or do I have to recreate them in the machining model?

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Re: Datum Target Points in Merged Model

Now I see what you want; as far as I can tell, yes you have to recreate them in the machining model

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Re: Datum Target Points in Merged Model

Have you tried making it an Inheritance instead of a merge?

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Re: Datum Target Points in Merged Model

I tried this but couldn't get it to work either.

 

I'm also not sure of the difference between the 2.

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Re: Datum Target Points in Merged Model

If you bring in the casting model as a workpiece in the manufacturing assembly, doesn't it bring in the datum points you need, too?

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Re: Datum Target Points in Merged Model

The points carry over but the datum target annotations do not.

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Re: Datum Target Points in Merged Model

Are the datum targets annotation features? If they are features then you should be able to use an inheritance feature to pass them from the source to the target model. I have not confirmed this (for annotation features) but inheritance allows for feature level control when passing to the target model. Annotation features did not exist when the inheritance was first implemented so they may not behave as other feature classes in this context.

 

One of the use cases for inheritance was specifically for cast/machined designs so it is useful for that. I have some data on the implementation of inheritance vs. merge functionality, I will post that when I dig it up.

 

 

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Re: Datum Target Points in Merged Model

I tried to do that and then do "show model annotations" but nothing comes across. I created these using the "datum target" feature under annotations and then created a Datum A with the datum tag feature (names might be wrong since I don't have creo in front of me)

Re: Datum Target Points in Merged Model

I just did a quick test case using inheritance. I can see the target annotation created in the source model within the expanded tree of the target model inheritance feature. Visibility is not affected by show annotations as previously noted.

 

With the target model active:

The datum tag annotation is not found by the search tool

The datum tag is not available for use as a datum when creating GTOL annotation features

 

This would lead me to conclude that it is not recognized as a datum tag in the target part.

 

I am not up to speed on the MBD implementation so it is possible that this is by design. I would open a call with PTC and ask what is the best practice to propagate  MBD datums when using top down design tools (inheritance). If they have not considered this with the latest MBD enhancements they need to.

 

Please post back here after PTC support responds.

 

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Re: Datum Target Points in Merged Model

I've seen a lot of problems in using layers with the use of Inheritance/Merge top-down methods.  I stopped using that technique for that reason.  What I do now is make a family table of cast generic, with machined instances.

 

I think you'll find that the points issue is layer-based.

 

Best of luck!

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Re: Datum Target Points in Merged Model

This issue logged in PTC support database. Workaround is re-creating the Datum Tag in the inherited part.

 

Inherited Datum Feature Symbol cannot be selected as a Geometrical Tolerance datum reference with C... 

 

Summary is:

 

  • Reported to R&D as SPR 7967632
  • Works to product specification for Creo Parametric
  • A change in functionality is being considered for a future release by Product Management but no timeline can be committed to at this time

 

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Re: Datum Target Points in Merged Model

Copy Geometry can copy annotations from one model to another, so using that instead of, or in addition to, merge might be an idea. Unfortunately, playing around here I can only get the datum tag to follow, not the target markers. I'm on Creo 3 at the moment, though, and Creo 4 has revamped the way MBD works, so it might work on Creo 4. Or you could probably do it by using symbols instead of the "proper" datum target markers.

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