What is the difference between Mirror and Copy in terms of bodies/comps?

[petrara]

What is the difference between mirroring and copying a body/component in terms of how Fusion handles them? I've got some issues lately with mirrored components, so I decided to copy/rotate instead. Not sure if the issue is related to the mirroring itself.

From what I could tell, copies of the same component act like "clones", whilst mirrored parts seem to be entirely new entities (having unique name), yet they will be affected by some commands, like Press Pull or editing the dimensions of the sketch, but unaffected by others like Extrude, or performing supplementary operations based on the original sketch (or even drawing in the original sketch).

All this rules and exceptions seem quite fuzzy for me... especially when to choose copy vs mirroring (assuming both can be used with similar results in a particular design - eg: parts to be copied or mirrored have a relevant symmetry).

Does anyone have a more clear understanding and would like to share it?

Thanks.

[jeff_strater]

This is a good topic, thanks for bringing it up.  There's a lot here, but let's start with the surface-level stuff, and we can expand from there if needed.

First, and most important, Mirror is, well, a mirror operation.  It will create a mirror image of the component/body you are duplicating.  Copy/Paste will not do this mirroring operation.  If your objects is symmetric, you can get away with a Copy/Paste.  If you can, then definitely, you should avoid Mirror.

Your understanding of Mirror is correct - Mirror always creates a new object.  Even for a component, Mirror creates a totally new component.

Copy/Paste acts differently for Bodies and Components, so that is important to understand, as well.  Component Copy/Paste is not really a true "Copy/Paste" operation.  This operation creates a new "instance" of that component.  All instances of a component share common geometry - bodies, sketches, etc.  Put a hole in a component, and all instances of that component will have that hole.  Add a sketch, and all instances will show that sketch.  Bodies, though, do not support instances.  Copy/Paste a body, and it will be a new body.  With one caveat - that Copy/Paste is a timeline feature itself - it executes at a certain point in time.  If you make changes to the body before that Copy/Paste Body operation, it will affect the copy, because it happens before the copy is done.  However, if you make changes after the Copy/Paste, those changes will only affect either the original or the copy, depending on what you've done.

I will try, later today, to record a screencast to illustrate some of this.  A video will make this much clearer.

[petrara]

Thank you for the explanation @jeff_strater  . Now I understand much better the behavior of "Copy" command.
Could you please go a bit in detail in regard to "Mirror"? I understand it creates a totally new component, but you also mentioned that "if possible", mirror should be avoided. Maybe you could explain around this subject? If a command is more "delicate" in terms of how it affects the design, is best to know most about it, so we avoid some of the issues...

Best regards.

[jeff_strater · Accepted solution]

@petrara - I didn't mean to imply that you should not use Mirror Component, only that if you don't need a true mirror, because your component is already symmetric, and can be positioned using a rotation or Joints, you should use an instance - it is more efficient, and will more accurately represent your BOM, if you take your design to that point.

Here is the promised screencast, with audio:

[Anonymous]

The video was great, and really helps the explanation...until I need a mirror (because my part is not symmetrical) and don't necessarily want to finalize all the geometry on the original until later. For instance, I'm designing a set of cabinets and the left and right sides are mirrors, but I don't know the final locations of the holes for the shelf supports until the client decides how many shelves.

[jeff_strater]

Sorry, I did not mean to imply that you should never use Mirror, only that you should understand the difference, and use each where appropriate.  If you really have a mirror-image component, then, by all means, you should use Mirror Component to do that.  Just understand that Mirror will create a new component.  That is good in your case, because it will allow you to put a different set of holes in the original and the mirror version of it, as long as you create those holes after the mirror feature in the timeline.  If you have more specific questions, feel free to ask.

[Anonymous]

Thanks for the quick reply!

I Didn’t get the impression from your post that I shouldn’t use mirrors anytime. The video was very helpful in demonstrating all the differences. I guess what I can do is modeled the cabinet literally without one of the other side, and when the shelf support hose or determined, make the mirror at that pointiDidn’t get the impression from your post that I shouldn’t use mirrors anytime. The video was very helpful in demonstrating all the differences. I guess what I can do is model the cabinet without one of the sides, and when the shelf support holes are determined, make the mirror at that point.

[spongman]

are there any plans to create mirrored component instances that bidirectionally echo edits to either the mirror or the source (much the same way as copied). if you can handle translations and rotations, why not scaling (include mirroring)? presumably it's just an affine transformation of the coordinate spaces of each component instance...