Forget everything you know about 3D printing – the ‘replicator’ is here • Hacker News Board

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#31

Post by arthurcolle » Fri, Feb 01, 2019, 12:28 PM UTC

DrAwdeOccarim wrote: post #18

pontifier wrote: post #12

This is very similar to a patent I have filed on extremely fast 3D printing. I have mentioned this method of 3D printing here previously. Transmitting data to a volume at high speed can be done in many different ways, at any scale, and with a variety of materials. I hope to someday demonstrate the printing of a 2 story concrete house in an hour using my technique.

Has the application published? Would you mind putting the link here? I'd like to read it.

Same here, I hope he can post it. Would be really interesting to read what techniques are being used to accomplish the claims in question.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#32

Post by jfoutz » Fri, Feb 01, 2019, 12:57 PM UTC

Leynos wrote: post #13

AstralStorm wrote: post #6

Uh, that's a standard resin printer. Except horizontal plus rotation instead of vertical. Trades angular resolution for vertical. Yes, they can be fast. They should fix their headlines.

Could multiple projectors (at e.g., 120 or 90 degree angles) be used to speed the process further?

furthermore, multiple projectors could increase resolution.

if there's an energy threshold to overcome to cause hardening, and if you can arrange for 2 sources to just barely exceed that threshold, then you could have very crisp prints.

chemistry is statistical though. you can exceed the threshold, but nothing happens because you get unlucky with some fraction of the light. You don't exceed the threshold, but you catch a bad reflection and harden stuff you don't want. and there's probably not a crisp threshold for hardening. it's more likely just time under light.

But i think you're right. two projectors at half power (let's pretend it's linear), with the projections 90 degrees out of phase, i think the print quality would go way way up.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#33

Post by yorwba » Fri, Feb 01, 2019, 1:08 PM UTC

singularity2001 wrote: post #16

I don't fully understand the process of creating 3D video from 2D slices. Is that some sort of holographic procedure? Presumably such a video could also easily be computed from CAD models, right?

Reconstructing 3D models from 2D projections is a popular exercise in applied linear algebra courses (actually, 2D images from 1D projections are more common, because it's easier to visualize). The procedure is pretty easy to code up once you've understood the mathematics. Essentially you build a system of linear equations describing the influence of material density on the measured intensity, then solve it for density given intensity. https://scikit-learn.org/stable/auto_examples/applications/p...

Generating projections from a model is much easier, because you only need to write the rendering pass and don't have to invert it.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#34

Post by jtraffic » Fri, Feb 01, 2019, 1:37 PM UTC

There are subtle differences between 3D printing types that seem at first to be the same.

Stereolithography is horizontal, one layer at a time, and uses photopolymerization (that's Formlabs). (Also Digital Light Processing is close but distinct: https://formlabs.com/blog/3d-printing-technology-comparison-...)

Continuous Liquid Interface Production (CLIP) also uses photopolymerization, but pulls the object from a liquid bath and uses a buffer zone. Still horizontal slices. The upshot is it's much faster. (Carbon 3D is the company behind this.)

The method in the article uses photopolymerization to solidify the object as a set of slices, but the slices are not horizontal.

The big drawback to photopolymerization is it only works on certain resins which can often have undesirable mechanical properties (high elasticity or brittlness, for e.g.) Potentially this method could be a way forward in that respect, because you might be able to put structural materials in the resin solution and end up with a composite. It seems easier to do this way than with CLIP or SLA/DLP, but I'm purely speculating.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#35

Post by regularfry » Fri, Feb 01, 2019, 1:39 PM UTC

manjana wrote: post #24

ricardobeat wrote: post #22

These resin printers have been around for a decade. Multiple kickstarters, several commercial models on sale right now. To classify as a ‘replicator’ it needs to be able to mix different materials (metal, plastic) seamlessly in one print as to be able to replicate itself. Not there yet...

My thoughts. I remember Autodesk made a resin print of the Eiffel Tower and some other object with plastic polymers catalyzed by light about 4 years ago, there is a video on Youtube of it somewhere.

This is much faster.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#36

Post by _Microft » Fri, Feb 01, 2019, 1:42 PM UTC

regularfry wrote: post #20

_Microft wrote: post #4

The speed is amazing but the amount of waste seems rather large as they most likely can't (re)use resin that has already absorbed (an unknown amount of) light before.

It doesn't work like that. It's like a match: put enough energy in, and it transitions to a new state. Put less than the activation energy in, and it doesn't. The energy you've put in will be lost as heat, but the resin is unchanged until it changes completely.

There's a minimum amount of energy required for the process to happen. Below that, it can not. Above it, things can happen but how often depends on the intensity of the light. Increasing intensity will make it happen a lot more often. Some parts will receive far more light then others, making the polymerization progress far enough to actually build a solid object while the rest of the volume is illuminated little enough for the resin to basically stay liquid. (Remember that you need to shine into the container, therefore illuminating liquid that you do not actually want to polymerize but need to shine through to reach the material that should. A sort of collateral-damage if you like). The remaining liquid material is removed but will still contain partially polymerized material that's not grown large enough to actually behave like a solid.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#37

Post by phkahler » Fri, Feb 01, 2019, 1:54 PM UTC

>> The device, described on 31 January in Science1, works like a computed tomography (CT) scan in reverse, explains Hayden Taylor, an electrical engineer at the University of California, Berkeley.

I have been wondering if something like that was possible. I've also wondered if something more akin to holography could be used to create a 3D interference pattern in a liquid to create an object. Both seem like they'd be interesting and have limitations.

From the comments here I think some folks don't realize the mathematical details involved in this - they are not projecting a "picture" of the object from each angle going around. Yes, it's an image, but not it's not what you'd expect. It's more akin to an x-ray of the object, and probably with some extra processing beyond that.

EDIT: Looks like I'm wrong. It says the create an image of what the object would look like from each angle. I believe that means their quality is lower than it could be had they actually used more sophisticated methods to create the images.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#38

Post by Franciscouzo » Fri, Feb 01, 2019, 2:13 PM UTC

jfoutz wrote: post #29

steriolithography[1] is neat, and i think older than deposition style printers. This is kinda wacky. Rather than a conceptually simple layer by layer approach, this has this funky convolution. they're getting it for free with the simple rotation. You can kinda see how bulbous that airplane model is, because some finer details get 'overexposed'. i bet, if they could rotate 10x around 1 axis and 1x around another axis,…

I don't think it would be possible to rotate around another axis, the printed object would start tumbling around the resin. If they rotated the projector instead of the resin it would be possible.

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#39

Post by mkeeter » Fri, Feb 01, 2019, 2:16 PM UTC

stubish wrote: post #2

While you end up with an acrylic model, this should be suitable for lost-wax style casting. Being able to create an unpixilated identical or scaled copy of a model will be fantastic for fine art sculpture (or destroy the industry, if copies become too easy to make). Just take your acrylic model, attach casting channels, cover in ceramic, dry, pour in your bronze, cool, crack, trim, patina, ship. Avoid all of the fidd…

[disclaimer: I work at Formlabs, a 3D printing company]

This is already happening for jewelry, digital dentistry, and medical applications – you can buy specialized materials for investment casting.

For example, here's our blog post on casting jewelry from resin prints: https://formlabs.com/blog/introducing-castable-wax-resin-jew...

Re: Forget everything you know about 3D printing – the ‘replicator’ is here

#40

Post by sonusario » Fri, Feb 01, 2019, 2:33 PM UTC

There is a more volumetric 3d printing method which prints all at once, no rotation required: https://www.llnl.gov/news/volumetric-3d-printing-builds-need...