Cold 3D Printing
August 10, 2013 03:13AM
This idea involves printing with two-component resins, glue / adhesive or silicone.

The object is printed inside its mold. The object and the mold is printed at the same time layer by layer.

The printing itself is similar to that of an ink-jet printer. Each layer is squirted out dot by dot on top of the previous layer.

The components of the materials should be mixed just in time. The curing should be fast. The curing can possibly be accelerated by using directed light or heat, like a lamp connected to the print-head. It is also possible to cure one layer at a time.

It is important to keep the surface layer level. This could be done by having a device for measuring distance attached to the print head. Add more stuff where needed.

Color, as well as liquid to control translucency and hardness, is mixed directly into the drop of liquid that is about to be printed. This makes it possible to print objects with unlimited variation of color, translucency and hardness.

It is also important to be able to print materials that don't stick to each other. One way to do this is simply have two different materials. The first material is for the object to be printed and the second material is for the mold. The mold material is preferably cheap and rigid.

For example, when printing a cartoon character with a traditional filament based printer, one would get a hard piece of plastic in a single color. When using Cold 3D Printing one could get a soft object with builtin skeleton, bendable limbs, proper eyes and all the correct colors and textures and mabe even hair if the resolution is good enough.

Using Cold 3D Printing one could have as high xy resolution as a regular ink-jet. The z resolution could be even greater.

The cons:
Can possibly take a lot of time to print anything, but it may be possible to print faster at reduced resolutions.

The pros:
It would be possible with this technique to create objects that was not possible to create before.
Can possibly have very high resolution. May even be capable of printing furry animals and eyeballs with transparency and all the bits and pieces inside. It is basically an ordinary printer with an extra dimension.
Will be able to print 3D object right out of a 3D modeler with textures.
Can possibly scale to very large objects because it cures fast and deforms predictably during printing, if at all.
Can possibly take gory special effect masks to the next level, even though this is not needed with all the CG.
Can possibly use great variation in different materials from things that look like flesh and wood, to all kinds of plastics and even things that just looks extremely realistically like something else because of detailed texturing and surface contours ( like a 100% realistic two by four with nails through it that is completely soft and harmless ).

Currently, affordable 3D printer have a significantly lower output quality than CG. This is not meant as criticism. I'm just saying that CG is very good, and when it comes to regular printers we can capture that easily in 2D. Cold 3D Printing could capture that in 3D by stacking regular prints on top of each other.
Re: Cold 3D Printing
August 10, 2013 03:58AM
Sounds awesome, have you tried building it yet?
Re: Cold 3D Printing
August 10, 2013 12:37PM
gmerz-

I would reason that the mixing nozzle would clog. Any power outage, or any hesitation on the part of the printhead, would allow the 2-component mix to solidify.

If the resolution is to be as high as an ink jet, the viscosity of the mix must be extremely low in the nozzle, and then harden rapidly after deposition. The nozzle size may be at least an order of magnitude less than the nozzles used to deposit viscous molten plastic.

Good idea. Is the technology there to create it? -Phuzzy
Re: Cold 3D Printing
August 10, 2013 05:06PM
Sounds like you need to work on developing the "hot-end" and nozzle - check out the bio-printers.
Re: Cold 3D Printing
August 10, 2013 05:55PM
What type of two part resin would you use? Does it exist?

What about hardening before it gets out -- plugged up tubing.

Perhaps a material that is set down -- then some other chemical to fix it.

Sort of like cyanoacrylic and accelerator

A injet type cartridge laying down part1 then another cartridge laying down the fixer.

How about laying down UV resin then passing over it with UV light
Very very thin layers cured very quick ---- super plastic jet 3D printer
Imagine 3 different colors of resins
Re: Cold 3D Printing
August 10, 2013 07:03PM
@cozmicray- isn't that how Objet/Projet works? UV cure every layer?

Throwing out a silly idea—what about using a paste extruder with a slow setting epoxy dough? It could be metered through a mixing chamber. Not sure how to balance slow set with quick removal from the build chamber though. Adding a post cure probably contradicts the Reprap ethos... I know this would be less precise than liquid resin but it seems easy to accomplish currently. If it has been done I'd love for someone to point me toward that research.
Re: Cold 3D Printing
August 10, 2013 07:17PM
grumpenstein Wrote:
-------------------------------------------------------
> @cozmicray- isn't that how Objet/Projet works? UV
> cure every layer?
>
> Throwing out a silly idea—what about using a
> paste extruder with a slow setting epoxy dough? It
> could be metered through a mixing chamber. Not
> sure how to balance slow set with quick removal
> from the build chamber though. Adding a post cure
> probably contradicts the Reprap ethos... I know
> this would be less precise than liquid resin but
> it seems easy to accomplish currently. If it has
> been done I'd love for someone to point me toward
> that research.

whats needed atm the a double-acting syringe driver , i've been playing with those one way check valves you get for $1 in the aquarium places and those are more than suitable for handling paste extrusion valving,

one material i'd like to do it with is liquidnails, it's dirt cheap it's already a s self supporting past and putting it directly onto a heated bed it might cure by the time the following layer is started




-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-



Re: Cold 3D Printing
August 10, 2013 07:32PM
doesn't this sound like fab at home project started by MIT?
Re: Cold 3D Printing
August 10, 2013 07:40PM
@jamedanielv

It seems like that project is dead, or at least their website and forum are.
Re: Cold 3D Printing
August 10, 2013 10:34PM
I can't find the link to an interview or better description, but my understanding is that this one is using a two-part epoxy that cures the instant it leaves the nozzle -

Mataerial
Re: Cold 3D Printing
August 11, 2013 12:08AM
@Ian Johnson– Amazing video...To me it looks like a urethane resin or very dense foam.
Re: Cold 3D Printing
August 11, 2013 07:20AM
I am not capable of building this. I suspect ink-jet printers are complicated to build. It could be possible to reuse components from an cheap store-bought printer, but I doubt it.

Concerns about nozzle clogging is probably well founded, but I'm guessing that it would be possible to mix and eject the liquid so fast that premature curing could be avoided even if the curing is very fast. Think about how fast an ink-jet printer-head has to operate.

I very much like the UV resin idea. Preferably one would cure the dots as the print-head moves along, but printing a layer and then curing it in two separate sweeps could be very nice. I'm worried the dots may mix in an undesirable way. That problem could be addressed by modifying viscosity and surface tension of the uncured resin. The alternating printing and curing layer by layer is probably the fastest way to print though.

Regarding the syringe based printers, I consider those different from this idea which involves:

1. print curing liquid one dot at a time, one layer at a time
2. print the mold and the object at the same time
3. mix in colors and other components ( hardner, softner, transparency ) as late as possible before ejecting the liquid

Regarding 3, I really believe that the mixing and printing can be done in one single burst. These liquids needs to be mixed also, and I think the inertia from the nostrils of the different components should both mix it and cause it to eject onto the surface.

This could happen so quickly that the chemical reaction that causes the curing would not even start until the dot has been put on the surface. Maybe it is even possible to use chemistry to accurately time the delay like those time-release mechanisms sometimes used in medicines. That way it would not cure at all in the nozzle but afterwards it could cure almost instantly.

On the other hand, maybe this just happen to be really simple to do using standard liquids and components. Maybe it will just work without much research, tinkering, calibration or redesigning.
Re: Cold 3D Printing
August 11, 2013 12:13PM
grumpenstein

Doesn't the objet / projet cure resin in a large pool of it?

I don't know if they lay down layers but set them in a pool of resin?


??????
Re: Cold 3D Printing
August 30, 2013 08:41AM
Hello
I am interested to find out if anyone has any information on foam 3d printing – I am interested to find out from a personal point of view for some small engine parts projects I would like to get off the ground at home looking to use some sort of lost foam casting ideas – so I need something that can 3d print and give me accuracy
Any help would be appreciated
Re: Cold 3D Printing
August 30, 2013 03:23PM
@williamsmpiper I don't know if polyurethane foams will burn out very cleanly. The combustion products will be ~disgusting~ however. If you were to go down this route you would achieve the best results by casting a plastic 3d print in a low density, closed cell 2 part foam. I can't imagine any accuracy printing foam above say 5mm. After all it expands pretty significantly. Unfortunately this necessitates making a rubber mold.
Re: Cold 3D Printing
August 30, 2013 04:58PM
You could probably use a plastic and then melt it out instead of burning it. With PLA you could easily melt it out in an ordinary cooking oven, probably even ABS.

Alternatively you could even dissolve it out by for instance making the positive in ABS and then dissolving it out with acetone. This may be preferable to melting as the acetone with dissolved ABS in it will more easily flow out of the sand mold than molten plastic would. You would then bake out any residue remaining so as not to contaminate the cast.
Sorry, only registered users may post in this forum.

Click here to login