Boundary fill? Something else?

[jwilkins8475]

I have an assembly that I'm trying to make a miniature model out of that's suitable for 3d printing. Before anyone asks, I can't post a picture of it or upload the design, as it's proprietary and I'm not about to get mixed up in international intellectual property laws.

You can maybe think of it as a model of the Earth, with all its oceans and mountains and caves and all that, but in reality, it's an egg-shaped module filled with electronics and other things - there are  hundreds of individual components. I've managed to use an ellipse to "hollow it out," so to speak, and get rid of the things a miniature model wouldn't need (PCBs, mechanical mounting points, etc.), but I'd like to fill the entire thing so that it prints as a solid piece while maintaining its outer appearance. I can't use the same ellipse that I did to hollow it out to form a "core" and just join it to the outer shell, as at the proper size, it either intersects with and sticks out past visible features, or if I go for the smaller end of the spectrum, it leaves the outer shell as a thin skin that's not really attached to the core at all, and ends up un-printable, even with supports.

I ran across the Boundary Fill command, which I never knew about, and it seems to be exactly what I'm looking for, but I can't make it work to save my life. I've, I think, closed up all the gaps and holes in the model's features, and put an offset plane on the top of the hemisphere, but no matter what (whether I get 100 cells or just one) it always finishes the compute and leaves me right back where I started - wondering how to fill a half sphere with material.

I'm sure there's a better or easier way to go about this, but even after watching around two dozen Boundary Fill tutorials, I can't figure it out. Can someone point me in the right direction?

[davebYYPCU]

Scaling down by a long way is fraught with errors.  You lose a lot of surface detail as well.

In that case, redraw at printer size a half section. and revolve it.

Exported STL files are hollow.  Slicing settings do the rest.

Might help...

[Drewpan · Accepted solution]

Hi,

Two points.

Why do you want to create a sphere or egg solid? It will use a large amount of material when printing. Spheres and

eggs are some of the strongest shapes there are structurally so as long as a hollowed shell is thick enough it will not

crack. It is actually possible to STAND on an egg and it will not break under the average load of a human (if you do it

right😎).

If what you want is just the outside then simply scaling the outside shell to the size you want and then turning it into

an stl file should work. You can set the wall thickness in the slicer and the detail will be printed on the outside and the

walls on the inside.

Cheers

Andrew

[jwilkins8475]

I did that with the shape I uses to hollow out the assembly and get rid of all the unnecessary interior parts and leave the outside untouched, but the interior surface is still very irregular. Using that shape to form a "core" still leaves me with voids and hollow points and parts of the surface that are too thin to print.

[g-andresen]

Hi,

As long as you do not upload the file with corresponding notes for review, the hints can be no more than a poke in the fog.

günther

[jwilkins8475]

Yeah, well, it's not my model to upload. Like I said.

[TrippyLighting]

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@jwilkins8475 wrote:
Yeah, well, it's not my model to upload. Like I said.

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Then create a dummy model that exhibits the same problem.

Otherwise you might just be out of luck!

[jwilkins8475]

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@Drewpan wrote:

set the wall thickness in the slicer

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This ended up giving the result I was looking for. Not sure why I didn't think of that. Sometimes you get set in a mode and end up wearing blinders, I guess.

The model ended up 1:10 in size, with 8mm wall thickness, and I no longer need supports of any kind.