So I’ve been thinking about making a 3D prototyping machine for a while now. I’m lazy and making the parts by hand is a chore. 3D printers and cutters open the ability to draw a model on my PC and create it without actually measuring and cutting all the parts.
So far I’ve seen a couple types
CNC Mills/Lathes (computer numeric control)
Deposition 3D Printers (Melted Wax or Plastic)
SLA (Stereo Lithography Apparatus)
Liquid Powder Printers (liquid hardener added to a powder bed)
Paper 3D Printer(sheets of cut A4 paper with glue)
1. CNC routers are great tools, they are subtractive and are used to manufacture parts out of wood, plastics, and even metals by cutting chunks from a solid block of material. Most CNCs have a cutting tool mounting on a XY linear slide which allows a cutting tool head to travel across the entire region. The tool head is mounted on a Z axis which lowers the head to cut or lifts it up to jog to the next area.
One of the big drawbacks of a typical CNC is the inability to cut underneath the material. Since the tool only cuts from the top you would not be able to do things like cutting the bottom of an arch without flipping the material over.
CNCs can produce very strong models. The result will have the strength of whatever material you cut, so long as your tool head is powerful enough to cut through.
Some great CNC links include
2. Deposition/3D Printers are additive. Instead of cutting away material they have a tool that deposits little droplets of wax or plastic. The plastic or wax is melted in the tool head and ejected out of a nozzle.
Most of the wax/plastic units I have seen offer no choice in colors. Wax tends to be weak and will break if dropped. The abs plastic depositing machines are usually strong. Comparable to Lego bricks. These typically can’t print archs either since the print head needs some support underneath in order to print successfully. Some printers offer two heads, one that ejects the material and one that creates supports that are removed after the model is finished.
RepRap is an interesting deposition type printer that uses a thermoplastics to create models too. Its more of a hobbyist machine that has the ability to machine it’s own parts. Replication! Well at least the non metal parts, circuits and others are still bought.
Another open source machine that has achieved some popularity is Fab@Home
Most of these machines though only print in a few colors, pretty much the color of the material being feed through the thermal extruder.
There are also some versions of these machines that use chocolates, sugar glue and other fun materials but the general rule is they liquidfy and deposit it in layers which eventually harden
3. Now SLAs are the definitions of awesome. They work with a bath of a UV sensitive resin. There is a platform that first sits near the surface of the bath exposing only a hairline fraction of the entire UV resin tank. A fancy 100mW or more UV laser turns on and cures the resin that it hits. The SLA machine does this layer by layer and since the laser is such a fine tool and more controllable than a extuder head it can achieve higher resolutions than deposition printers can.
These models have great accuracy but their models also only come in one color. The models are fairly strong, stronger than wax but most plastic printers can printer stronger models.
To my knowledge no one has made a homemade SLA.
4. Now I added the powder type 3D Printers into their own category because even though they deposit materials they act similar to SLA. In a powder type 3D printer there are two trays. One for powder to be used and one for the model. The model tray is initially empty. It then gets filled with a layer of powder and a print head moves over the powder depositing a liquid hardener that reacts and hardens the powder at select locations. Another layer of powder is then added and the process repeats until the model is done. Then the model is separated from the unhardened powder and is dusted off and sealed. Because the powder acts as a support complex shapes can be made. If the model was a hollow ball the powder material would support the shape while its being printed but it would come out as unhardened powder.
Since these liquid deposition tools don’t need to be heated they usually rely on a inkjet like tool head which allows it to easily achieve higher resolution since the tool head is created by a stereolithograpy method and it is typically faster since the print heads have a matrix of nozzles.
Also a lot of these models use actual inkjet print catridges so a wide variety of colors can be printed on the model. Something the other machines did not offer.
There have been some successful replications of these machines but none that also produce color on the DIY side of the world. Let me know if you find one and I will post it.
5. Paper 3D Printer? Now this one is a completely new concept. MCOR had the bright idea to glue layers and layers of paper while cutting the paper to make a 3D model. I have to say this was pretty smart. The models come down drastically in cost since glue and paper are commonly avaliable and cheaper than thermoplastics. (I don’t even want to think about how expensive the SLA resin is ) Now this company hasn’t actually sold their printer but its pretty interesting. It seems like it would be a lot greener than the other methods. CNCs produce waste, thermoextruders produce heat and their models are not always recyclable and SLAs are extremely expensive.