Edit existing model with hundreds of referenced features?

[JLude_86]

Hello everyone! I'm hoping someone here will be able to give me a hint or some pointers as to how to deal with a modifying an existing model feature with many features referenced to it.

A little background, I just started this job last week and have been somewhat familiar with creo (or so I thought) prior to starting with my new employer. They have asked me to take a model with nearly 300 features and modify it. The problem is the portion of it I need to model is basically at the top of the model tree so any modifications I try to make instantly cause a hundred or so features not to regenerate. I realize that this is difficult to answer without the model. I am looking for more strategy/approach solutions to this. Is there something I can do to modify the feature (a protrusion) without completely screwing the entire model up or is there no way around it but to do the changes and then reassign references?

I apologize if I missed a discussion topic similar to this and I appreciate any help/insight you may have!

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[TomD.inPDX]

This is the reason Co-Create maintained an edge in the industry: sustainability!

This is also the reason PTC created a Direct Modeling extension/option.

But to address you problem, I have to ask what your employer's standards are for modeling. If they want clean, easy to modify, logical model trees, then you ran across one that got past the checkers.

It is always dangerous to update a primary feature when you don;t know how the other features were related to it. You must review the model before anything else. You might even export a STEP file so you have an overlay for later.

Next, find out how and why all those features are failing... or how they are related to the primary feature and the change you are trying to make.

In the end, if it doesn't matter to anyone but your own sense of completeness, there is no reason you can't just fill in a region and re-create what you need to change. Yes, it is messy, but it is the fastest way to get what you need. Personally, it would bug me a lot to have to do that.

I have seen a lot of really cr@ppymodeling in my time. And mistakes from these models are super easy to make when you overlook something simple in the far corner of the drawing that should not have been affected. The end cost can be catastrophic! Be careful!

As for eliminating dependencies, I try to features in the model tree. This tells you what is dependent on what. I start grouping features (not a group feature; just move them together) and see if it has a completely useless relation. It is all too easy to just "click something" to make a relation... where you should always go back to some primary feature if you have any scruples at all (which you obviously do or your wouldn't be asking ).

If in doubt, ask you boss as to how they want you to proceed.

[TomD.inPDX]

...and welcome to the forum!

[ptc-5008082]

Start with your reference viewer and see how many faces etc are referenced on the features you need to change. If there aren’t millions you can try re-routing references to remove these dependencies.

Most people use ‘Edit References’ to change the references of a feature but you can use it to swap out an old reference and put in a new one.

Easiest way to think of it is as a model with a cube right up there as the first feature of a big old tree, it has 6 faces that could have things hanging off.

Work out where the faces are in space and create datum planes in the same position with the positive (brown) side of the datum plane pointing in the same direction as the solid face.

Make sure these planes are right at the top of the tree and preferably dimensioned from default datum planes.

Then use right mouse button Edit References on any feature in the tree (doesn’t matter which)

Select No for rolling back the model and then select Replace Ref from the menu manager

Leave it on Indiv Entity and then select the old reference – face 1 of cube and new reference – matching datum plane 1

Select All Children and all of the children that were using the face now use the plane.

If you do that 6 times in my example you can now delete the original cube as all of the children will now be routed to the newly created datum planes.

Obviously if it is not a cube you are starting with then creating something suitable as a replacement reference will not be quite so easy!

[JLude_86]

Thank you Charlotte! Your post certainly helped clear up some of my questions on the options in the menu manager and I intend to try your suggetions. I didn't realize there was an "All Children" option so that my help tremendously.

[Dale_Rosema]

I would also save a copy if possible. Name it similar - oldmodel_test_junk (something that you'll remember to delete later). That way you have a copy to reference in case things go ca-flooey. I always find that helpful too.

[dgschaefer]

Spend a couple hours studying the model, understanding the design intent from how it was built. Try to get in the head of the guy who built it, then you'll be in a much better position to make changes.

Creo has some very robust tools for reference management and it is generally very consistent in how it treats reference entities. The technique Charlotte described is one that you can use to replace an old reference with a new. There are also a replace tool in sketcher that will allow you to take an old sketched entity and replace it with a new. (There's also a 'replace' button in the references dialog, but that's not what I'm talking about here.) A sketch entity has an ID and it creates surfaces with IDs. When you delete something in sketcher, you break all the references down the chain, those IDs are gone. However, if you use the replace command, you can remove one sketch entity and replace it with another and all the IDs remain the same downstream. Creo will attempt to rebuild the geometry with the new entities in place of the old.

Keep in mind these relationships and look for ways to maintain the entities or replace them using the edit reference or replace tools and you should have good success.