topic Can't delete sphere in STEP file in Fusion Support Forum

Can't delete sphere in STEP file

jim_thompson1 — Tue, 16 Nov 2021 23:50:27 GMT

I was trying to create a hollowed out version (in order to put cockpit etc) of this model https://www.thingiverse.com/thing:1691788 but get a weird behaviour. The original STEP file is referenced in the link above which I import to fusion360. A few simple extrusions and I get the basics of what I want however when saving the mesh as STL for 3d printing the sphere which the model is no doubt based on is present and the model is solid. Visually on Fusion360 it looks hollow and a section analysis confirms it is hollow (as per attached screenshots). There seems to be a trick in order to delete the sphere in the first place which is to rotate the STEP file a random angle before doing a circle extrusion cuts into the sphere. If you try and save the file or enable design history the sphere reappears so it must be present in the model at some root level. One attached picture shows the sphere that reappears after extrusions if you enable design history, save etc. I can't seem to select the sphere at anytime. Extrude cutting into this sphere has no effect.

No doubt Fusion 360 is not the best program to do this but I am most familiar with it and seems easy to achieve my desired result. Any tips how to delete this sphere?

Re: Can't delete sphere in STEP file

TheCADWhisperer — Tue, 16 Nov 2021 23:54:32 GMT

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

Re: Can't delete sphere in STEP file

jim_thompson1 — Tue, 16 Nov 2021 23:58:30 GMT

Wow, that was fast. Here is the f3d file as requested

Re: Can't delete sphere in STEP file

TrippyLighting — Wed, 17 Nov 2021 00:08:40 GMT

Can you share the original .stp file ? (zip before attaching)

Re: Can't delete sphere in STEP file

jim_thompson1 — Wed, 17 Nov 2021 00:16:49 GMT

Hi, original free download file I am using as mentioned is at https://grabcad.com/library/tie-advanced-x1-1

Re: Can't delete sphere in STEP file

TrippyLighting — Wed, 17 Nov 2021 02:08:14 GMT

Interesting!

From a CAD / Solid model perspective, this is quite a terrible model. While Fusion 360 recognizes this as a soli model, I don't believe that is justified. There is all sorts of internal structure that should not be there in a solid model.

I use another CAD software ZW3D and hat does not recognize the main model as a solid body but as a surface body. It also reports an enormous amount of gappy edges and a good number of other problems. The standard stitch tolerance in ZW3D is 0.01mm, and with that, I also could not stitch the mode into a solid. More experimentation is needed.

If I don't forget I'll check this out tomorrow in SolidWorks on my work computer.

Either way, this isn't per se a Fusion 360 problem. This is a pretty bad model!