Dimensioning Externally Generated Body

[FK_7297405]

Hi,

In order to limit the number of individual components and separate dimension changes in a CAD model, I decided to model all components as separate bodies within the same file. This allowed for easier relations alteration and referencing between bodies (eg. remove intersected body, add hole through all intersected geometries, etc). Once all the component were finished, individual parts could be generated for dimensioning and assembly purposes using the "Create part from body" feature.

Currently,  I am unable to see any reference axis or points when I go to dimension the individual part. "Annotate<Show Model Annotations" does not bring back any dimensions or reference points (No annotations can be shown in the current sheet/view for the selected objects). I am not sure if this is related to how the body was created or what the implications of copying external geometries features may do when trying to dimension a component - by all expectations I expected this to be a useful feature for multi-body modeling.

Help with this would be appreciated!  

[tbraxton · Accepted solution]

I have not tested this in Creo 7. Reading about the functionality when you create a part from a body an external copy geometry feature is created in the part. You can add references to a manually created ECG to include datum features, try to redefine the multibody generated ECG in a part and test if you can add datums from the master model to the extracted body part.

You should be able to add another ECG feature to include datums if it is not possible to add them to the auto generated ECG in the body part.

Datum refs in external copy geom

[barryschaeffer1]

Within the parts that you exported, have you had trouble showing dimensions using the Show Model Annotations command?

[tbraxton]

No but I am not using Creo 7 for production work. I think your question is different than that of the OP and is probably valid. I suggest that you start a new post detailing your specific issue. I infer from your query that you are attempting to show annotations that are defined in an external model propagated to a derivative model using external copy geometry in the derivative model.

[FK_7297405]

Yeah exactly that, the auto dimension tool does not identify any dimensions native to the copied geometry. I’m not sure how to get around this.

[tbraxton]

If you are wanting to show dimensions on a drawing of a copy geometry feature, that is not supported. Dimensions are not propagated in copy geometry features.

One workaround is to use the inheritance option (merge/inheritance) functionality in place of copy geom. This will bring the features (and therefore dimensions) into a derivative model. Since all features are accessible in the derivative model they can be shown in a drawing view. I strongly suggest that you understand the differences between inheritance functionality and copy geometry before adopting this approach in a production environment. One risk is that uneducated or careless users can propagate mistakes (up and down the top down hierarchy) through your design models unknowingly by manipulating inheritance features in derivative models.

[tbraxton]

I have just confirmed that the method in my post above does work.

1) Open the part created from a body

2) Redefine the ext copy geom and select the references tab and activate the references collection box

3) Select the datum references as required from the master model

4) LMB "OK" to finish the feature

You will now have the desired datums from the master included in your part

[FK_7297405]

Hi Tbraxton,

Thanks for the insight, would you be able to explain where you found your redefine commands for the ECG? I tried doing similarly, but could only view the "Edit references" and "Reference Viewer" utilities with base ID references from the original multibody part - not the screen that would allow me to enable the reference collection box as you mentioned.

Much Appreciated!

[tbraxton]

This short video will explain it in detail. One caveat is that you must have a license that supports the top down design tools which includes copy geom features. If you do not have the required license then you will not be able to edit the definition of the ECG.