The Makerbot Process

I wanted to write up this post for two reasons; one, to explain a do-it-yourself 3d printing platform to those new/curious, and two, to provide a solid explanation for those interested in purchasing a makerbot (a pretty hefty investment for most). Forgive me if some of this is rudimentary… I wanted to paint as complete a picture as possible.

SO. The Makerbot is a fused deposition modeling (FDM) printer (follow the link for more information on the process). All you need to know right now is that it prints plastic in a layer-by-layer process.

The printing process can be broken down into two major steps: computer software pre-processing and actual physical printing. I will limit this explanation to the Makerbot specifically.

First, a 3d model is designed in pretty much any 3d modeling software program. When it is finished, the model has to be processed before the 3d printer will understand it. Since the Makerbot prints layer-by-layer, the model needs to get sliced up (among many other things). The software run by most Makerbot users is currently Skeinforge, which happens to be totally free and open-source.

Skeinforge contains all of the settings for the user’s particular Makerbot– from speed, layer thickness, and extrusion temperature down to the exact distance the plastic extruder turns on before laying down a path (in fractions of a millimeter). These settings can (and must) be edited to get the most out of the printer. The 3d model is chopped up into thin layers by Skeinforge, and the output is a set of instructions that a machine can understand and use to build the model. The instructions are in a language called GCode. Since Skeinforge knows the details of the particular Makerbot, it tailors the build instructions to get the most out of the printer. When the instructions are compiled it lets you view them layer by layer. It uses lines and arrows to show you precisely what the printer will be laying down. Here is an example window from a build I did:

GCode is a simple language used by computers to control machinery. Most lines in a GCode program are literally just “move here” and then “move there” and then “move back here.” It controls other aspects of the machinery as well; a CNC router, for example, has a milling bit and the GCode might tell the bit how fast to spin. In the case of the Makerbot, the GCode controls the position of the build and the speed and temperature of the plastic extruder.

The prepared GCode is loaded into a program which will communicate with the Makerbot. The program Makerbotters use is called ReplicatorG. ReplicatorG specializes in reading GCode and translating it into Makerbot language. The Makerbot itself has its own program on it which specializes in turning ReplicatorG-Makerbot-language into physical movements.

Setting up the Makerbot to print is very easy. You have to put either foamcore or acrylic on top of the build platform, which snaps into place on the bot. Once ReplicatorG is open, you can jog the X, Y, and Z axes so that the print head is positioned a fraction of a millimeter above the center of the platform. When all is ready you hit the “Build” button!

So to give a brief overview, the process can be summed up like this: 3d modeling -> conversion to GCode (Skeinforge) -> printer setup (ReplicatorG) -> print!

From a designer’s point of view, the process is quick and virtually painless… When iterating and prototyping a design, the first thing you notice is how little time you actually spend designing. Having access to a machine like this is invaluable.


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