Fusion 360 Shell question (here instead of main list)

[Kathryn Born]

Hi All, 

If I don't find a solution here, I'll post on the larger group - this just seems a little niche of an issue. 

Ok - Fusion 360. Grrrrr. 

I've got 2 things I need to do that generate errors in fusion with a cryptic message and no clear way to fix within the software. 

1. Making something hollow

2. Converting to Brep and hacking a downloaded model

These issues/errors are somewhat similar

1. To make something hollow, you use the shell tool. Except the shell tool craps out with an error. (see image) I can get this to work if I do one face at a time, which is nonsense. I've putzed around with the "Delete tool in the patch workspace" and I have 0 idea what I'm even trying to accomplish by "not repairing the gap."

Does anyone know? 

My second question is similar, I import a small mechanical gear "thing", and try to convert it to BRep so I can modify the mechanism for a wind up motor. The error says it has too many faces, and you can't select just one section. In some forums, people talk about reducing the faces in software I don't have. Are there any solutions in Fusion 360? 

OK, just throwing out darts to see if anyone knows what I'm talking about and has worked through this. 

Thank you in advance if anyone knows this. No worries if no. 

[Ray Doeksen]

Should link to the source of the file ... there may be something going on that the file itself is responsible for, we can't tell without it though.

Where is the elephant shape from?

How thick is the shell supposed to be? 2 mm?

Do you absolutely need to convert to Brep to get the gear-results you need? 

[Ray Doeksen]

Youre making this hollow in order to build it out as the housing of a mechanism, right?

Have you tried working on a half of an elephant, with the whole elephant assembled afterwards?  

There may be a different process that comes to mind if you keep the actual final goals in mind. You don't NEED to make it uniformly hollow right off the bat, you need to get your motor inside, that's a slightly different thing. 

[Kathryn Born]

Hi Ray, thank you for the reply. The file is now here - http://a360.co/2sLjSuM

It needs to be hollow for 2 reasons: 1. so it can house the mechanism, and 2. so it will be pretty. For the flea circus, the beauty is in the motion of the gears itself, not the exterior. 

The inspiration was this video -- they found this Faberge egg from 1919 that had an elephant walk out.  https://vimeo.com/141676340 (I don't want the rider on top). 

But anyway,

With clear SLA printing, the word "transparent" is thrown around loosely. I think those elephant body walls need to be as thin as I can print them so you can see the gears and machinery. This can somehow be adapted for a 4- legged walker. https://www.youtube.com/watch?v=nBy2W23qlAM . This one is simpler but it limps around. https://www.youtube.com/watch?v=VbSL5W8Ua6M

Another beautiful elephant. This shape might give me more options, but I just wanted to get the first shell printed out and then just play around with it and see what could work. 

Thx in advance for looking at it. 

[Kathryn Born]

Realized I didn't really answer the question. So part 2. 

Yes, it could be sliced in half or with the legs separated. At some point, I would have sawed apart the model. 

My other option is a resin mold, and the hell with SLA printing, but I like the printers and I'm not into mold making anymore. 

K

[Ray Doeksen]

I think, that since what you are after ultimately is a framework, a housing for one of those coiled-spring motors, that you want more than just a shell, and ... will the mechanism drive the legs or something?

Or just vibrate it along? 

If you need to chop off the legs as separate parts and maybe the head, going from that STL from thingiverse might be introducing some bad geometry that you don't need to work with.

You could shell it in the slicing software by just demanding 0% infill?

[Kathryn Born]

The legs would move/walk/stumble. 

But right, Cura has a hollow option and hollowed it out in one click. But PreForm (Form 1) doesn't offer that (as far as I've researched and heard), so you have to import it hollow. So if I could import to PreForm as gcode from Cura, it would work, but ... alas. 

So right, I'm sure it's just some bad geometry, but my own designs aren't likely any better. Anyway, my wish is that Fusion would write more clear error messages and offer a path to remedy it. This model was originally thingverse, then I lowered the poly count 60% in Maya. The original model caused an error, my version caused an error. 

Ultimately, I'm looking for a 3D modeling tool that will help me mod found models better. Like the tri-color walking machine turns out to be downloadable stl already - https://grabcad.com/library/walking-robot-mechanism-1 - but I wasn't able to put it into fusion and pull it apart. Maya was slightly better, but still made a mess of it. Fusion has a feature that's supposed to convert these things, but they generate errors in reality.

Anyhoo - that's for giving it a shot.