How do I create a mechanism but use assembly references to create the part and avoid circular references?

[ptc-4397158]

How do I create a mechanism but use assembly references to create the part and avoid circular references?

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[TomD.inPDX]

These are two different questions. Either you have external references in your part or you don't by eliminating then as you clean up your part file.

If you are using dynamic references dependent on your mechanism position, you probably cannot update the part during the analysis playback.

Generally you are limited in many respects when you try to use dynamic values without regeneration. It is pretty much self protected from doing this.

If you have a more specific example, maybe we can find a way to solve your challenge. Maybe I am overthinking your question.

[ptc-4397158]

Thanks for the response Antonius. Let me be more specific. I am trying to setup a simple pin mechanism. My assembly has 2 parts with a pivot point on each part. I created the second part by creating a component in the assembly and referencing the assembly datum planes. The pivot point on the second part was created by referencing the pivot point on the first part. I want to be able to change the position of the first part's pivot point and have the pivot point on the second part automatically update when regenerated. I then added a pin connection to the placement of the second part and removed the datum plane references so it would move. When regenerated I get circular reference warnings even though the mechanism does move but the base part spins around as well.

[ptc-4397158]

Attached is a very simple example of what I'm trying to do.

[TomD.inPDX]

It never pays to shortcut the assembly process. In this case, I would not have tried to create the new part in the assembly.

If nothing else, I would have made prt0003 with only a set of datum planes and a datum axis and assembled with this the pin constraint.

I may also have has the primary pin axis as part of the assemble datum set and constrained both parts to it.

In general, mechanism constraints will be very particular as to which part or assembly the subsequent selections will allow.

There are occasions where you can confuse the system, obviously.

[ptc-4397158]

After some more research, it looks like skeletons might be the answer. Especially as the model gets more complicated.

[TomD.inPDX]

There is some planning to do, and skeletons makes this simpler. Core Creo doesn't have skeletons so I have to make due with what I have. But there always seems to be a way to "make" it work

[dgschaefer]

What you are doing is what Solidworks calls "in context editing". It's actually a recommended top down design technique in SW, but in Creo it can create a mess (I'd argue it does in SW too, but that's for another forum). Directly referencing another part within the assembly for feature creation is generally a bad idea in most circumstances. Better to pull down from some kind of master part or skeleton.

If you have Advanced Assembly Extension (AAX) skeletons are very robust and powerful. The skeleton or master part would contain the basic geometry needed to build each part. I like to put geometry in my skeletons to represent anything that two or more parts need to share. You then create a publish geometry feature in your skeleton for each part that needs geometry out of the skeleton. That publish only contains the items that part needs. In your part you'd use a copy geometry in the assy to select that publish geometry and pull that data into your part. You'd then build your features off of that copied geometry. For parts that move, you'd need to use an external copy geometry feature that removes the assembly position from the equation. You'd need to either use the default position or a coordinate system to locate the copied geometry.

If you don't, you cans till use a skeleton like master part to drive your assembly, however the parts need to remain fixed to each other in order to copy geometry. Copy geometry and publish geometry features will not be available, but you can use a merge feature to bring your entire master part into each component. In order to create the motion, you'd create two assemblies, one where the parts are fixed to each other and where the merges are created and another where you'd create the mechanism constraints.

Those are very basic descriptions of the processes involved, but hopefully should get you started on the right track.