Copy Geometry? or Drive Extrudes from other components in Assy

[mmead]

I’m going to try and make this make sense.

We’re populating the inside of a shelter system with stuff.  On the floors, walls and ceilings are a lot of holes to mount things to.  As we install components were adding holes to the base shelter model and then constraining stuff to the holes. 

When we have the end item produced in real life we need drilling templates for all the surfaces.  We are modeling the templates to mimic the surfaces as we go.  I want the surface of the shelter to drive the position of the holes in the templates.

Should I put a blank template in the shelter, activate that template, and drive the hole placement by referencing the features in the assembly?

Or should I add Copy Geometry to the blank component model tree and drive the entirety of the template off the copy geo?

If I drive everything from features in the assembly I have the benefit of being able to move the template around on the surface, the holes stay constant to the shelter, and fall where ever on the template.

If I use Copy Geo I don’t really get to choose the placement of the template, it lives in default location.  And it seems location is defined on the sketching location referencing the Copy Geo

I was told once that copy Geometry was a more stable answer than using features in an assembly to drive features in a component.  But in the grand scheme of things this template is a simple piece.  Do I need to worry about stability in something simple, if in fact what I was told was true?

I feel like this is a lot of typing that probably didn’t do a great job explaining my problem.

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[dschenken]

Assembly cuts are computationally expensive, or at least memory expensive, because to create them Creo creates an on-the-fly family table to manage the cuts. That's how intersected parts can appear in one window with holes and another without - they aren't the same part.

Copy-geom is more straight-forward and only duplicates the selected geometry.

It could be done by assembling parts representing the templates and tying holes in the mounted components to axes and datum curves for the templates.

I would not worry too much about using holes in the shelter to locate the items; the assembly should reflect the desired outcome, so if a cabinet is to be 20 inches above the work surface let Creo do the work to track where the cabinet mounting holes need to be relative to the floor.

The problem that can come from doing things the 'right' way is that if one mounting hole gets moved and the related assembled component moves, but the other holes don't move and it goes unnoticed because the model covers it up and there's no mismatch warning. If datum curves/axes are driven back from the assembled location then they can't avoid lining up (tolerances aside.) Why do I mention this? I've seen it happen. That's when people start looking for those offset bolts that don't appear in the Mil-specs or the McMaster Carr catalog.