Researchers at McGill University have successfully "printed" a variety of objects in ice using a modified a Fab@Home Model 1.
In addition to objects printed directly in ice, such a printer can be used as an early step in lost-ice casting.
The concept of an IceRap is to use water as a feed stock. This water is deposited onto a cold surface in a sub zero build environment. After being deposited the water freezes and then the next layer is deposited on top to build up a 3D object.
If this could be done successfully with a respectable resolution then water could be used as a cheap, near unlimited and environmentally friendly feed stock.
Obviously, any object printed from ice wouldn’t last long at room temperature and so would limit the useful applications. Although it could be an alternative for test test prints of half finished models with out wasting filament. Parts could also be stored in a freezer until needed.
Possible design ideas
This is only one possible method.
Step 1 - Create a sub zero (degrees Celsius) print environment
Probably the most practical way of doing this would be to place the entire 3D printer into a walk in freezer or similar. Alternatively, an insulated build area such as Nopheads 'wooden overcoat' or the Gunstrap's insulated build chamber could be actively cooled. This could be achieved through the use of a conventional compressor based system scavenged from an old freezer, a thermoelectric cooler (Peltier) or through the use of dry ice/liquid nitrogen. The system used isn't important provided the print area is well below freezing over the duration of the build.
Step 2 - Use your 3D printer to deposit fine beads of liquid water
The idea is that you deposit a very thin bead of water onto your build surface is the same way that would extrude plastic. Once a layer has been laid down there would be a delay of a few minutes while it freezes in the cold build chamber. Once frozen, the next layer is deposited and the process repeats. By keeping the beads of water only a few millimetres in size surface tension alone should be enough to keep them in place. I suspect that even limited overhangs could be achieved. Once printed, a quick once over with a hair dry or heat shrink gun would turn the object clear.
So how would you deposit very small beads or even individual droplets of liquid water in a controlled manner? Well thankfully this problem has, for the most part, already been solved with Adrian Bowyer's Reprappable-inkjet print head. Adrian's reprappable inkjet. A video of the print in action can be found here. With a little tweaking it should be possible to further reduce the size of the output nozzle jet to increase the printable resolution. It would also be necessaries to insulate the inkjet head and feed pipe to stop it freezing as it operates in a cold environment. Similar precautions would also be needed for the electronics and stepper motors if directly exposed to the cold. Condensation would be the real killer hear.
Step 3 - Use your 3D printers heated bed to help remove the printed object
If you use a heated print bed, this could be used to remove your printed ice object. It could also be use to help dry out a heated print chamber after an ice print.
There have been a few very successfully teams working towards ice rapid prototyping. A few include;
Professors Pieter Sijpkes and Jorge Angeles and other researchers at McGill University have successfully "printed" a variety of objects in ice using a modified a Fab@Home Model 1.
Missouri University Of Science and Technology
Please added any suggestions or ideas, no matter how small.
Some possible (fun!) applications could include:
- Sip your next Martini out of a cocktail glass made of nothing but ice.
- Adding food dye for colourful creations.
- Include cordial in your feed water so your printed object is edible and sweet.
- Print your own spiral drink cooler that cools your drink as you pour it.
- Design an ice swan centrepiece for your next dinner party.
- It might be possible (even though not easy) to supercool the water and let it crystalize as it exits the noozle, thus building the sculpture faster.
- Perhaps an IceRap could make some of the parts for a child printer -- Self-Replication. Either indirectly with lost-ice casting, or directly out of ice for parts of a IceRap that always stay below freezing.
The design could be made stronger using Pykrete instead of ice. Pykrete is a composite material made of approximately 14 percent sawdust or some other form of wood pulp (such as paper) and 86 percent ice by weight. Its use was proposed during World War II by Geoffrey Pyke to the British Royal Navy as a candidate material for making a huge, unsinkable aircraft carrier. Pykrete has some interesting properties, notably its relatively slow melting rate (because of low thermal conductivity), and its vastly improved strength and toughness over ice; it is closer in form to concrete. At room temperatures, it melts much, much more slowly, though little testing has been done to date. Pykrete could be used to make permanent, useful objects in colder latitudes from ubiquitously-available materials.