topic Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata in Fusion Design, Validate & Document Forum

Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

zackfranchino — Sun, 25 Sep 2022 14:58:13 GMT

Not sure if this title is any good (it isn't) but I'm hoping someone can help me out or at least point me in the right direction.

Just recently started playing with Assemblies in Fusion360, and I'm hitting a snag with this particular assembly and cam combination.

The assembly works fine when manipulating the lower rod manually:

And it works when using an offset circle as the cam:

And this cam works by itself:

But not together:

As you can see, the cam just gets stuck. I went up the chain of joints, disabling one at a time, waiting for the point where it would break, and I would know which joint was causing me problems... But it never happened. Each individual thing worked, just not when connected to the rest of the assembly.

Any other tips/tricks appreciated as well, especially pertaining to modelling automata in fusion 360.

Thanks in advance!

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

TrippyLighting — Sun, 25 Sep 2022 07:02:47 GMT

Can you share the model?

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

zackfranchino — Sun, 25 Sep 2022 14:59:17 GMT

Yep, I just attached it to the original post

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

TrippyLighting — Mon, 26 Sep 2022 13:48:51 GMT

Are you familiar with Fusion 360 R.U.L.E #1 & #2 ?

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

zackfranchino — Mon, 26 Sep 2022 17:16:50 GMT

I'm not familiar with those! Mostly self/Youtube taught. I gave your link a read, did I create something out of order?
Like I said in the OP, this is really my first real foray into components and assemblies. Most of my Fusion360 experience up to this point has been designing things for 3d print, so I've used/created bodies, but never had a use for components.
Any ideas for me? Not strictly opposed to starting over to do it properly if I need to.

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

jeff_strater — Thu, 06 Oct 2022 22:22:17 GMT

Pretty sure this is a bug with tangent relationship. I noticed that the main extrude for your cam is broken:

and I thought that might be related, but I rebuilt that cam a couple different ways, and still had the same issues. So, I think it is more geometry related than anything - something about that cam profile (composed of all arcs) seems to cause problems. Even adding fillets on the sharp corners did not help. I created bug FUS-114622 for this issue. Thanks for reporting it.

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

TrippyLighting — Thu, 06 Oct 2022 22:34:40 GMT

@jeff_strater Thanks Jeff! I had lost track of this thread ...

Re: Inconsistent behavior when using assemblies/tangent relationships with irregular cams. Automata

zackfranchino — Sat, 08 Oct 2022 04:37:05 GMT

Well, can't say I'm happy about the outcome, haha! But thanks for looking into my issue. I'll keep trying to rebuild the cam in different ways and hope to find a solution.