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.
- Fused deposition modeling (FDM): the typical plastic filament-extruding hobbyist printer. Low resolution, but fast and creates very strong parts in one of wide varieties of well-known engineering materials. Tricks (e.g., two extruders) can give limited multiple colors or materials.
- Selective laser sintering (SLS): a laser melts a pattern into one layer of powder at a time. Can make even stronger parts than FDM by using nylon, titanium, etc. Very common in industry, but usually too expensive for hobbyists. These are the printers used to make rocket engines.
- Stereolithography (SLA) as explained above works like SLS but cures liquid resin with light instead of melting powder. Has many subvarieties. Advantage is scary high resolution (certain engineering choices give 160 nm (!) feature size [1]), but at the cost of relatively limited material choices because materials need to be liquid UV curable (though Form 2 has a good library now [2]) and definitely no multi-material or color parts. I'd consider this new 3D rotation printer a variety of SLA. [Edit: for clarity, I lumped CLIP and DLP here with SLA]
- Inkjet-based printers: these are the _really_ cool ones. Objet makes a printer [3][4] that uses inkjet heads to deposit multiple colors and materials in the same part layer-by-layer (kind of combining FDM and SLA). Upside is multiple colors and materials and resolution (e.g., Lego uses these for prototyping), downside is ridiculous price and low speed. Other printers like HP's and Z Corp's combine inkjet heads with SLS powder instead.
There are also a few weirder ones, e.g., paper layering, but I don't think they're widely used.
Another con to resin based approaches that's not always obvious is that some of these resins are pretty nasty and dangerous to touch when wet or pour down the drain. That makes the cleanup process a pain, at least in the context of at-home or small-scale printing. Powders are aslo a big pain but they're too expensive anyway.
The big problem with stereolithography resins is that they tend to degrade with time, especially if left in the sun. Photocuring is carried out by creating free radicals to induce polymerization. Well it turns out that these same free radical producing chemicals stick around even after the curings done and can make more free radicals if left in light. These free radicals can cause some pretty nasty damage to polymer chains. The chemistry is improving though, at the very least to allow more interesting materials like silicones.
One can mix in composites to stereolithography resins, but in general this isn't done. The problem is that whatever you mix in scatters light, so light doesn't penetrate as deep, so curing takes longer. Unless the composite used is transparent and has the same index of refraction as the resin, it would not be possible to use this tomographic approach to make parts.
There is one application of composites that's extremely disruptive though: producing ceramic parts. It has been found that you can mix in ceramic powder with the resin fire it in an oven to make very detailed ceramic parts[0]. Structural properties aren't necessarily that good, but that's ok because it's good enough to make very complex and detailed investment casting molds[1]. Investment casting molds for making single crystalline jet turbine blades are very complex and require a very complicated process to produce, with this process they can be made in one step. That's a huge disruption right there and investment casting is a pretty general process. The detail produced by this process is so high that the the triangulation of STL became a problem and a special file format developed for fax machines had to be used to represent all the slices.
The other benefit with having multiple projectors/lasers at different angles are that you can use different wavelengths: one that causes polymerisation, one that inhibits it.
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, that tumble would sharpen up some of those edges, since you wouldn't be baking the same adjacent space so much.
Think about a 6 sided pencil. if you just rotate around the main axis, it's probably going to look pretty round without the crisp hexagon sides. but if you can also rotate around a minor axis, you could also project just the hexagon shape for a while and still preserve the cone of the tip of the pencil since most of the solidification came from the sides.
There's an opportunity for deep optimization there. Seems tricky. but pretty cool.
it's almost like pca. what projection (or series of projections) maximize hitting the target, and minimize the overbaking, all while taking into account the characteristics of the resin. maybe you can let it cool for a bit, and have more freedom to expose without hardening.
also, not a replicator. this is just one _fabulously special_ super material you mess with, not metal and plastic and cloth and fur and chitin and whatever.
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.
No it isn't. A normal SLA printer like a Form One prints a slice at a time and crucially it doesn't "print" in the middle of the liquid - only at the surface.
This works as the article says, like a CT scanner in reverse. The resin solidifies all at once in the middle. It's very different.
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.
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.
>> 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.
Holography actually sounds pretty promising but the issue is that most holography systems are phased (they trace the hologram with a single laser.) If a holography with hjgh energy could heat up the inside shape of a liquid in a beaker, it could turn it into a solid. The issue would be thermal diffusion but if a dense enough liquid were used, it could work!
> The team realized that the process could be reversed: given a computer model of a 3D object, the researchers calculated what it would look like from many different angles, and then fed the resulting 2D images into a ordinary slide projector.
I'm pretty sure the researchers were using a normal computer projector and not a slide projector. But in my imagination, they printed a bunch of slides, fed them into a carousel projector, and pointed them at an old Smuckers jelly jar full of resin.
Readit News
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.
- Fused deposition modeling (FDM): the typical plastic filament-extruding hobbyist printer. Low resolution, but fast and creates very strong parts in one of wide varieties of well-known engineering materials. Tricks (e.g., two extruders) can give limited multiple colors or materials.
- Selective laser sintering (SLS): a laser melts a pattern into one layer of powder at a time. Can make even stronger parts than FDM by using nylon, titanium, etc. Very common in industry, but usually too expensive for hobbyists. These are the printers used to make rocket engines.
- Stereolithography (SLA) as explained above works like SLS but cures liquid resin with light instead of melting powder. Has many subvarieties. Advantage is scary high resolution (certain engineering choices give 160 nm (!) feature size [1]), but at the cost of relatively limited material choices because materials need to be liquid UV curable (though Form 2 has a good library now [2]) and definitely no multi-material or color parts. I'd consider this new 3D rotation printer a variety of SLA. [Edit: for clarity, I lumped CLIP and DLP here with SLA]
- Inkjet-based printers: these are the _really_ cool ones. Objet makes a printer [3][4] that uses inkjet heads to deposit multiple colors and materials in the same part layer-by-layer (kind of combining FDM and SLA). Upside is multiple colors and materials and resolution (e.g., Lego uses these for prototyping), downside is ridiculous price and low speed. Other printers like HP's and Z Corp's combine inkjet heads with SLS powder instead.
There are also a few weirder ones, e.g., paper layering, but I don't think they're widely used.
[1] https://www.nanoscribe.de/en/products/photonic-professional-... [2] https://formlabs.com/materials/ [3] https://www.youtube.com/watch?v=M1sOdZqwn5Y [4] https://www.stratasys.com/polyjet-systems
There is one application of composites that's extremely disruptive though: producing ceramic parts. It has been found that you can mix in ceramic powder with the resin fire it in an oven to make very detailed ceramic parts[0]. Structural properties aren't necessarily that good, but that's ok because it's good enough to make very complex and detailed investment casting molds[1]. Investment casting molds for making single crystalline jet turbine blades are very complex and require a very complicated process to produce, with this process they can be made in one step. That's a huge disruption right there and investment casting is a pretty general process. The detail produced by this process is so high that the the triangulation of STL became a problem and a special file format developed for fax machines had to be used to represent all the slices.
[0]https://www.researchgate.net/publication/229293237_Photopoly... [1]http://ddm.me.gatech.edu/page8/page8.html
* rotating the projector instead of the tube to reduce distortion from resin movement (like in a CT scanner)
* speeding this up, using higher energies to compensate
* using multiple projectors at e.g. 90degree angles, to reduce time (and thus probably distortions through movement in the resin)
* using other wavelengths with e.g. more energy, or just better absorption properties for the resin
or are there any obvious problems with that?
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, that tumble would sharpen up some of those edges, since you wouldn't be baking the same adjacent space so much.
Think about a 6 sided pencil. if you just rotate around the main axis, it's probably going to look pretty round without the crisp hexagon sides. but if you can also rotate around a minor axis, you could also project just the hexagon shape for a while and still preserve the cone of the tip of the pencil since most of the solidification came from the sides.
There's an opportunity for deep optimization there. Seems tricky. but pretty cool.
it's almost like pca. what projection (or series of projections) maximize hitting the target, and minimize the overbaking, all while taking into account the characteristics of the resin. maybe you can let it cool for a bit, and have more freedom to expose without hardening.
also, not a replicator. this is just one _fabulously special_ super material you mess with, not metal and plastic and cloth and fur and chitin and whatever.
[1] https://en.wikipedia.org/wiki/Stereolithography
Their problem is that the projector they are using is projecting a 2D plane.
It would be a different story if it was a circular projector (think of a LED strip).
It has to be then rotated only along a single axis.
Turning the projector circle physically can possibly add additional precision.
Magnetic fields can be used to keep the container sphere in place.
I am now going to take the screenshot of this conversation and send it to my self in a registered mail.
Yes, they can be fast.
They should fix their headlines.
This works as the article says, like a CT scanner in reverse. The resin solidifies all at once in the middle. It's very different.
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.
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...
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.
I'm pretty sure the researchers were using a normal computer projector and not a slide projector. But in my imagination, they printed a bunch of slides, fed them into a carousel projector, and pointed them at an old Smuckers jelly jar full of resin.