unable to SHELL and SPLIT nor SPLIT and SHELL body from STEP file

[bradanlane]

I am trying to work with this (https://www.thingiverse.com/thing:1363148) object.

gecko model courtesy of WebmasterZero

I need to scale it up, shell it, split the shell, and then add things like screw holes, mounts for small LEDs, etc.

The author posted STL, IGS, and STEP files.

I can SPLIT the STL but I end up with infinitely thin walls which I can not thicken and can not add new design to.

I can upload the STEP file and SPLIT it but then I can not SHELL it.

I'd be interested in suggestions for steps which may work.

[bradanlane]

I tried uploading the IGS file and running a similar flow as with the STEP file:

1. upload
2. open
3. stitch all faces (this step was not required with the STEP file)
4. scale
5. create offset plane
6. split body

The result was the same. I get an error "No intersection between target(s) and split tool.

During the slit operation, it is clear the extended plane cuts through the entire body.

[TrippyLighting]

Splitting might be the current hurdle - although it did work for me - , but the real road block will be shelling it. This is complex geometry that was created by converting a qualms into a NURBS model either using T-SPlines or PolyNurbs evidenced by the 32MB file size of the STEP file. It also  has tight radii in some places.

[bradanlane]

Actually, a simple SPLIT using an offset plane is not a problem.

My solution has been to split the body into "top" and "bottom", project the split surface onto a sketch and then manually create a few enclosed splines inset from projected edge. I then create several extrudes only as much as I needed to fit the electronics inside.

It's not pretty on the inside but it will work.

[TrippyLighting]

That s probably the best approach in this particular case.

[bradanlane]

for completeness, I tried creating a series of offset planes. Then, projecting the model body where it intersected each plane. The hope was to create a series of outlines which I could then use to loft. That wasn't successful..

For some reason, the projected outline was not contiguous. Even after editing to make it contiguous, I was not able to create an offset. Forgoing the offset, I decided to just try creating all of the outlines and attempting the loft. Fusion 360 froze up on the third sketch plane.

[TrippyLighting]

That approach had zero chance of success 😉

Ideally you would have had access to the original quad mesh this model was created with. That would have allowed you to easily modify the critical areas around the eyes and mouth in sculpt mode and possibly would have increased your chance of being able to split shell this object.

But even then Fusion 360 might have had a problem shelling this. For example I tried splitting the model in halve vertically between front legs and rear legs and then just shell the less critical tail end. Fusion 360 didn't do this.

The other more powerful and mature (and more expensive) CAD application I use had no problem shelling the tail end, but only shelled the front with a really thin wall thickness due to the tight curvature. However, it also has many more options to deal with self intersecting geometry, which would have allowed it to create a thicker shell. However, I did not pursue.