Breaking the link of any imported object breaks my model

[clyde.fare]

On a long-running project, I've recently noticed that if I import anything and then break the link I get errors and several operations in the history go red indicating a problem. This happens for any object I try to import but only if I break the link. Running compute-all (in my main project) prior to importing does not catch any issues.

From what I can see there is a mirror operation within history which stops working after importing an object and breaking the link. Fusion360 does not flag the operation itself as problematic but when rolling history back to that point no mirrored components are getting created and as a result all subsequent operations on those components are failing.

Any suggestions?

Cheers

[davebYYPCU]

Without the file, we have read between the lines.

If you import the object, at the end of the Timeline, and immediately break the link, do you get failures?

If there’s an import, more modelling and then break the link, does that cause failures?

The suggestion is to investigate why the mirror fails, may be unrelated to unlinking an import.

Might help...

[clyde.fare]

"If you import the object, at the end of the Timeline, and immediately break the link, do you get failures?"

Yes

"If there’s an import, more modelling and then break the link, does that cause failures?"

Yes.

"The suggestion is to investigate why the mirror fails, may be unrelated to unlinking an import."

This makes a lot of sense, but I don't really understand how to think about this problem. If there's an issue with the mirror wouldn't compute-all catch it? I have attached my project file to this message hoping it will clarify my remarks (ran out of time to edit the original one). 

Many thanks for time.

[TrippyLighting]

I just started looking at this.

A mechanical assembly such as this one should not include any (body) move or position capture features.

[jeff_strater]

When I open this model (which appears to be post break link), it does not contain any errors, and compute all does not report any errors, either.

Can you share the design (F3Z) before the Break Link?   And, indicate which particular external component seems to be the problem when you break its link.  Thanks.

[jculleton3]

I often have this problem. Most often it is when the object I imported isn't really a complete object. (best way I could describe it).

For instance I create drawing and design something like a hinge or other thing. I assign constraints and or dimensions to the bodies. 
Where the mistake happens is I then create a component and add the bodies to the component so I can add ASSEMBLY CONSTRAINTS and then Save the component as (give it a name).

When I add the component to another model and break link I get all kinds of yellow messages and sometimes red.
Mostly because in my modeling frenzy I deleted a body or some other object from the main model I was working on and when I save the component the drawing / surface / plane / or previous body that was a reference no longer exists. 

I have finally gotten disciplined a little and make sure to move my sketches into the component before I extrude (afterwards it gives an error). I also stopped using the delete function for anything that once was used as a starting point and used remove instead, (it makes the component bigger in memory even though I can't see the removed object). 

I have had to open the component (model I saved from a component is more like what I mean) and then look for errors. Many times I have to open a new blank model and start a sketch on the bad model, project surfaces and edges, copy it to the new blank model by creating a new sketch and pasting it in there. Then I can re-extrude and do other things and have a model that won't break when I save it and bring it into a new drawing. 

The biggest mistake I have been making is creating complex models in the main level component and then try to save bodies as components which sometimes breaks because later in modeling I do something in that main component that deletes, removes, changes the base model or sketch the new lower level component was based on.

I know I don't explain things well but hopefully you find a useful answer somewhere in my ramblings.

JC

[TrippyLighting]

You probably want to clean up your workflow and not move sketches into components. You should first create and activate components and then add stuff to them.
See Fusion 360 R.U.L.E #1 &2

[jculleton3]

I just downloaded his file and it looks fine. 

I added a simple solid model of a HawkBill knife blade and it breaks the model big time. 

So I suspect there is something that was removed or deleted that causes the failure?
JC

[jculleton3 · Accepted solution]

Ok... I found where the model breaks and I have uploaded a screen cast. 
I can add an object and break it up to a certain location on your timeline. 

When I get to that point a REMOVE INSTANCE lights up red and a previous save position lights up yellow.

I believe your problem is in the remove instance. 

You may have to save an older revision of the model to a new name and then import changes to that model.

Good Luck that's all I can offer.

JC

 
This is the screencast URL but it is still processing.

https://autode.sk/3oBHrV9

[jculleton3]

sorry for the bad audio. Had the laptop lid closed OOOOPS.

JC

[clyde.fare]

Thank you very much for looking into my model!

Just so I understand, you have identified a point where a position somehow depends on an object that is then deleted and that this is causing the problems. To remedy this I should use a previously saved version that has been saved before I deleted the object/performed the position and then recreate my model from that point. You mention a means to reimport the changes I made to this new version model - how do I do that? Or do i need to do it manually?

One other question: why does compute-all not throw this error but importing an object and then breaking the link cause it? I guess this means I have to be very careful when deleting components because doing so can secretly break the model but i can be none the wiser until a much later stage.

Many thanks for all your help.

[TrippyLighting]

@clyde.fare I create large assemblies in Fusion 360 most days and have never seen anything break in any of my assemblies, because I inserted an completely unrelated component. The reason for that is that I have a very solid method for assembling my designs.

Lets start at the very beginning of the design:

You create several bodies and then move the bodies away from the origin, before you convert these bodies into components. That means that the components you have created all have the same origin, but the bodies are not located at a sensible point in reference to the origin. Not a big deal, just a design practice I would not recommend.  

Origins is one of the first things I look at when inspection other users assemblies.

You also mirror components, which is another practice I don't recommend in Fusion 360. Instead of 1 line entry on the BOM with an instance counter for all identical AL struts, you'll now have 2 line (or more, depending how often you have mirrored the same components) items, one for e originals, and one for the mirrored ones.

Then even though you already have properly assembled the frame using rigid joints, you then use a rigid group joint and assemble the whole frame again. Also not recommended.

Are you familiar with Fusion360 R.U.L.E #1 ?

The design has many instances of you first creating sketches and then bodies from sketches ad then converting the body into a component. Not recommended (see R.U.L.E #1).

To be continued ...

[jculleton3]

Yes. Make a second version before the offending remove command under a new name. 

When you start building from there try and import pieces of the old project.

In other words save out components and open them up by themselves. See if moving it around or what not breaks it.

If it doesn't break then you can use it in the new model.

I often violated the Rule#1 mentioned by TrippyLighting and have to take the component in question out of the model (save component as) and often then recreate the component by using the model as a sketch source and create a brand new component of the offending object. 

Its a pain but I have learned that I should always always always make a component first and then work on it. Otherwise I often break stuff. 

JC

[clyde.fare]

Thank you for your suggestions. As is perhaps clear from my model, I am not experienced with the use of CAD in general or Fusion360 in particular. I had not realised that first creating bodies then converting them to components was unwise and will endeavour to follow your Rule 1 in the future.

Regarding mirrors I had thought them very useful time savers because many of the components i've worked on have symmetry. Instead of using mirrors do you suggest using a rectangular pattern or are you suggesting that I should not use these kinds of 'short-cut' features at all?

[clyde.fare]

Ok understood, I will mark your previous post as the solution. Thank you for your help in this matter.

[TrippyLighting]

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@clyde.fare wrote:
... Instead of using mirrors do you suggest using a rectangular pattern ... ?

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Yes. Does not work in every case, but should work in this case.

I use all sorts of tricks to be more efficient, so no worries. Sometimes I even mirror components, because when I develop concept designs I don't need a BOM (Bill Of Materials).