Are there any shapes that a 3d printer can't print?

[bordelond]

Sounds like the powder-based printer mentioned in **Folly’s **post #16 could handle this, but:

Is a linked chain a significant challenge for a 3d printer? Or was it once a challenge for the early models?

[TriPolar]

@bordelond

Sounds like the powder-based printer mentioned in **Folly’s **post #16 could handle this, but:

Is a linked chain a significant challenge for a 3d printer? Or was it once a challenge for the early models?

It could be done if each link could be supported separately from the others so they don’t touch. It’s not really a practical use for a 3D printer though.

[AndrewL]

@bordelond

Sounds like the powder-based printer mentioned in **Folly’s **post #16 could handle this, but:

Is a linked chain a significant challenge for a 3d printer? Or was it once a challenge for the early models?

Not really, you just need enough ability to handle overhangs to print open loops. Most cheap hobby printers can print interlocked objects.

[Saint_Cad]

What about a true Menger sponge?

[Machine_Elf]

@Saint_Cad

What about a true Menger sponge?

What is a “true” Menger sponge? If you mean one composed of infinite iterations, then I agree. But for some finite number of iterations, it ought to work just fine, right up to the limit of resolution of the printer.

[Ethilrist]

@Folly

It also depends on the type of 3d printer. The large (expensive) Selective Laser Sintering machines would not have a problem as the layers are built up by in layers of powder. So you have the powder there to support the structures that are temporarily ‘floating’.

3D printing tech may have changed since I first saw it; if you tried to print an object that was completely enclosed within another one (say, a ball inside a sphere to make a rattle), even if you could print the interior ball resting on the bottom of the larger sphere, wouldn’t the space between them (and the interior of the inner ball) be filled with the unused fusable printing material?

[Folly]

@Ethilrist

3D printing tech may have changed since I first saw it; if you tried to print an object that was completely enclosed within another one (say, a ball inside a sphere to make a rattle), even if you could print the interior ball resting on the bottom of the larger sphere, wouldn’t the space between them (and the interior of the inner ball) be filled with the unused fusable printing material?

It’s been 13 years or so since I last had access to one, but yep I think you’re right.

A rattle would defeat it without further modification.

[TimeWinder]

@Folly

A rattle would defeat it without further modification.

This would defeat every 3D printing system I’m aware of, ignoring “cheats” like making the ball-container connection so weak you can shake it apart. The usual solution to this case (and a lot of others where the whole object is “unprintable”)would be to make the “container” in two pieces which snap or screw together.

“Some assembly required” printing can probably print nearly anything, but likely violates the OP’s intent.

[Folly]

Well there we go then as an answer to the OP! a rattle!

[msmith537]

We have one in the office (for some reason). You can add some scaffolding around portions of objects that are floating in the air. Sort of like a “sprue” used in molded parts. Then just break it off when it’s finished.

[Chronos]

You could also make a very small hole in the outer shell, to drain the excess powder out of.

[eltro102]

the 3d printer could first make a hemisphere and then possibly form a droplet of its resin and drop that from the nozzle so that it hardens enough not to adhere to the hemisphere already formed and then build the rest of the sphere on that