Fusion does an impressive job on Assemblies and multi-body parts.  Inventor on the other hand gets quite jealous…


In this article I’ll discuss some things regarding the Fusion/Inventor interaction regarding multiple component files.  I tried to push the limit on what it was designed to do and kept hitting the wall.  This article is the result.

The Inventor/Fusion functionality Simplified

Inventor starts the Change Manager when a Fusion DWG file is opened.  It then opens the original Inventor file, runs the Change Manager, and parses every change made by Fusion into the original file.  You could say:

  • Inventor is like the house
  • Subsequently, the part file is the man, and Fusion is ‘the pub’
  • The Fusion DWG is a cab ride home.
  • That leaves the Fusion Change Manager.  That’s the man’s lady. Her job is to make sure that the man comes back in ‘one piece’ (pun intended) and that anything on the man is, well …acceptable. 

If the man leaves and returns later in a cab, the lady is sure to come to the door and give the man a once over. If she thinks he’s been unfaithful, like coming home with someone else in tow, then she may refuse to let him back in, or refuse to communicate with anything but anger if the man does get in. You can’t blame her for being upset.

Assemblies (the Pub Party)

I gotta tell you I was VERY impressed with how well Fusion deals with an Assembly.  It is slick as greased glass.  Navigation was well laid out, and fast to navigate and isolate components.  Load time was fast as well.


There was a specific issue I had opening an assembly in the Inventor 2011 Beta (hush hush and all that), that did not yet get worked out yet.  Fusion blew past it like it was nothing. 

Here’s the down side.  When Inventor sees the Fusion Edited Assembly coming at it, it slams the door. (No pub parties allowed back at the house). The Fusion dwg will be opened as a non-Inventor dwg.  The changes will be there, but all the intelligence will be lost.


Opening a Multi-Body and Multi Component file (Getting the man and…someone attached to him into the house)

Multi Body and Multi component files refer to (ipt) Part files specifically. Multi-body is similar to what you would see in Inventor. Multi-Component is a result of inserting a component into the part framework, similar to a block in AutoCAD.

I decided to split a single body part into two separate bodies to see what I cold accomplish.


Fusion treats these very well, especially multi-body. I wanted to leverage this functionality, but that is not permitted at this time.


The Change Manager will permit the edits back in, but unfortunately only one body or component can stay.  Any added components or additional bodies in the part file will be dealt with in the Change Manager.

So she will give you 3 options:

  • Don’t get in
  • cut off the offending body by removing it limb from limb
  • or rejecting changes that caused the second body.

Imagine an irate wife with a machete trying to get rid of the companion, while you tell her to please put down the machete. She just start swinging in an attempt to separate the foreign body.  You really don’t get to say anything about it, and before you know it, you get cut up.  The Change Manager isn’t listening, and her mind is made up. Very often, the desirable portion is what gets whacked.


In the image above, I wanted to keep the red portion, but the Change Manger sees things differently.

Inevitably, it is not as fun as intended.  In some cases it is possible to reject the multi body changes, and retain some important modifications, but this completely depends on the operations.

Deleting the other body while in Fusion (lose it before you leave the club)

This will only work if you do not reference anything to do with the extra body.  Once any interaction is performed with the second body, the damage is done.  She will smell the previous companion as soon as the part comes home.  I kid you not, and the hacking process begins.  Not a pretty picture.

Inserting a component (umm, you get the picture)

Remember, this is a part file.  Inserted components will become a portion of the part.  Inserting a component and trying to get back into the house like that is SURE DEATH. The Change Manager will just go ape ! 

Here’s the funny part: Once another component is inserted, the original part file is forgotten.  Inventor then drags everyone to the OTHER COMPONENT’S house, by opening that file instead.


The Change Manager will go crazy, and tear out the original part data, because he doesn’t belong there. Remember, she tears things down, face by face.  No one makes it out alive.

Deleting the Inserted Component in Fusion (trying to get away afterward)

Forget it. Just as soon as the component is inserted into the part file, it is cursed, no matter what you do.


Ok, I went long to have some juvenile fun with this, but it’s ok.  I hope this article will help new users from heading the wrong way with too much time invested, and current users with some explanations for issues they may have experienced.

Fusion is really powerful, and can be used to get things on track in a hurry, and to improve the welfare of the part in the prototyping process.  The Change Manager keeps things on the up and up, and gets the changes back into the history based model browser.  Using them together as they have been designed provides a powerful option to sudden changes in the part design. 

Just remember that Fusion is still a technology preview, and is not intended to be a full functioned prototyping solution. 

As soon as I can determine a way to indicate which body to keep, I’ll post it immediately.  Unfortunately until they add multi-body functionality to the Change Manager, multi-anything is just not…safe.