World's Most Clever 3D Printer?

A few of the tech newsletters I get were abuzz this week about the Peachy Printer, a $100 3D printer that's based on a saltwater tank.  Yeah, that's what I said.  

The printer achieves its low cost, as a kit, by coming up with a way of eliminating the most expensive portion of a typical 3D printer, the structure including the XYZ motion control, motors and the large table which objects get printed on.

Most of you have seen something like the MakerBot, the Cube, or something from the open source RepRap project.  These printers produce their objects by applying a thin, molten layer of various plastics on the printer table.  The mechanics are quite similar to a CNC router, with an XY table, and a Z axis that raises and lowers the plastic heater/extruder.  The Peachy Printer is a stereolithography printer, which was really the first type of 3D printing and rapid prototyping developed.  In this approach, the object is  made by shining a laser on a fluid resin that polymerizes into a plastic where the laser hits.  A few thousandths of an inch below the top of the fluid was a platform that the plastic was formed on.  The platform is lowered and layer by layer the object is created.  The result was usually a thin, translucent, plastic shell model of your object. 

Peachy's first clever trick is to replace the large tank full of this fairly expensive material with a thin layer that floats on saltwater.  The next trick is that instead of precisely lowering the big table, they eliminate the table entirely, and raise the floating layer of resin higher as the part builds.  A saltwater drip system, like an IV, raises the level of the resin and allows the newly made object to hang down into the water.  The laser that polymerizes the plastic is directed by mirrors positioned magnetically by galvanometers, much like the coils in electric (analog) meters.  Instead of driving motors with a stepper motor controller, the mirrors are positioned with analog voltages - sounds - produced by the ubiquitous sound card in every computer.  The deflection (angle of the laser) depends on the sound level, which is usually pretty precisely controlled by the output DACs.  Check out this video and the one on their home page.


Peachy Printer has gone through capital raising with Kickstarter, GoFundMe, and BackerKit, raising the better part of a million bucks. 

Now for the bad parts, the "watch out for".  They haven't published any specs, yet, on how big an object it can print.  The website says nothing is shipping yet, and printers are expected to start shipping in July.  The Kickstarter fundraising started in September of 2013, 18 months ago, and they've already shipped out some beta test units.  I didn't dig very deep, but I think it's a safe conclusion that if early beta test went well in 2013, they'd be in full production by now.   The cheapest printers are $100 kits, there are also $400 and $1000 price points (different sizes).  The resins aren't exactly cheap, but you don't appear to go through a lot of it. 

One to keep your eye on.