Cold 3D printing [solved?]

Cold 3D Printing V 2.0

I think I have cracked it, and it turns out to be much simpler than I first anticipated.

First I like to remind the reader how Cold 3D Printing works:

The 3D printer is basically an ink-jet printer, but instead of printing only a single layer of ink on a sheet of paper, it prints layer upon layer on top of each other to form a prism. Instead of ink, the material used is two-component resin that cures as it is printed.

Also, since one must print each layer on top of the previous, each layer must be completely filled in. The positive( the printed object ) and the negative( the mold ) is therefore printed simultaneously. After the entire block is printed, the object can then be separated from the mold. As a result one needs to be able to print two different resins that do not stick to each other, one for the positive and one for the negative.

Additionally one can add color or other chemicals that modify the qualities of the materials like transparency. This is done for each individual dot separately. Notice that the resolutions here is as high as an ink-jet.

The big problem, that has been pointed out to me, is that, as the resins need to cure quickly, the nozzle will eventually clog up. Also, even though ink-jet printers are old news and available in every store, replicating this technology in the garage may be costly, time-consuming and difficult. I believe I have solved both these problems in one big swoop.

The trick is to mix the resins using the same technique already used by ink-jet printers to mix ink. The inks are mixed on the paper and not in the cartridges ( on some printers at least ). A little bit of blue is squirted on top of a still liquid dot of red to create purple. The amounts of each color component is varied to create different colors. The magic is that the printer already does this out of the box. By changing the ink in the cartridges with resin components and controlling the "colors" printed, one can turn the ink-jet into a 3D printer without touching the electronics that produces dots. It will, however, be necessary to control the elevation of the print. It may be possible to find a printer where the paper is still while the print-head moves in the x y plane.

As an example, lets rework a photo printer that uses four ink cartridges, red, green, blue and black. Lets call these A1, A2, B1 and B2 respectively, and remember which is which for later. There are two different resins, A and B and each of them have two components. The two components of A is A1 and A2 and B is created using B1 and B2. Fill up the respective cartridges.

The computer model of the object to be printed must be scanned virtually and for each layer one must create a picture where the parts inside the model must be purple, 50% "red" A1 and 50% blue A2, and the parts outside the model must be half bright dark green, 50% "green" B1 and 50% "black" B2. I am assuming the 50% mixing ratio for both resins.

The resins must be chosen carefully of course. There are calibration issues. Liquid must continuously flow into the cartridges from large containers. There should be more cartridges to a printer. At least 5 more totaling: A1, A2, B1, B2, Red, Green, Blue, Opacity and Hardness. Adding cartridges to a printer might be problematic.

I am just making up this stuff as I go along. I am not going to build this myself. I'm hoping someone else will. I strongly believe that technology always approaches imitation of life and Cold 3D Printing will provide photorealism to 3D printing and it is difficult to see anything bad about that. Given the possibility of mixing resins outside the nozzles I think this could be done relatively easily by someone with the right skills. The difficulty level should be that of making traditional 3D printer from scratch.

Awesome idea or what?

Is there a resin available with the same low viscosity of ink-jet ink?

And will it respond to whatever is used to drive the droplets from a printer?

I'm not going to mess up my 8 cartridge printer !

....R

I'm guessing that there are materials like resin, silicone or other that will both have low viscosity and cure fast enough. The speed of printing may be adjusted accordingly. It may even be possible to use the same liquid as in a DLP projector based printer. The dots are very small, so could cure very fast. The liquid could be thinned out with alcohol that evaporated almost instantly.

I don't know how a dot of liquid is propelled from the print head. Mabe the ink has some metal particles in it. I don't know wether that will pose a problem. Mabe something will need to be added to a standard resin.

These questions can be answered by wrecking a very cheap printer. I'll see if I can get one of those cartridge refill kits for my 30$ 2-cartridge Cannon, but I have to research which resins to try.

8-cartridge printer sounds interesting. What is it called?

So you are looking for an element that can be in one state ready to print and then change that state once printed.
Having solved those problems you do realize the higher the definition the thinner the layers the more passes are needed. It'll take several days to print a lego man

Yes, yours is a more general description: "an element that can be in one state ready to print and then change that state once printed".

The possible resolutions here are crazy. Check out this 17" wide 9-cartridge printer: [www.epson.co.uk] . It has a resolution of 2,880 x 1,440 dpi. It would take a long time to print anything at that resolution as you point out. I do not think it is a problem given the potential quality of the result. Imagine printing a hamburger that is so realistic it's like a picture of a burger. Even the textures and consistency would be so perfect that you could not tell that it is fake until actually tasting or smelling it. It could be so realistic that a person without smell or taste could eat the whole thing without realizing that it is fake.

It may be possible to deliberately pick a donor inkjet that has low resolution and is very fast. That way one could get lower z-resolution and faster prints. I haven't researched this yet.

Here is a fast 300dpi inkjet head [phys.org].
Given that head, I get 1795272 dots/minute. A 4"x4" square contains 1440000 dots. That makes 1.25 layers/minute.
To build a cube of 4"x4"x4" would take 800 minutes or 13.3 hours at a resulution of 300dpi on all axis. This assumes that the dots are cubes which they are not. They would be more sphery and possible shorter then they are wide, so multiply the time to print by, say, 4 to get 53 hours at most, mabe.

Anyway, printing will be slow at this resolution. I don't find it that discuraging. I consider this to be more of a production method for stuff that cannot be produced by any other means than a rapid prototyping machine.

I think all the good Epson photo printers use 8 cartridges. My R1800 is a few years old now so I presume there is a newer model.

...R