3D Printing

A place where current 3D printer users can document the process of 3D printing.

Introduction

The printer currently being used in the physics lab Dennis 128 is a MakerBot Replicator 2. The Replicator 2 can print both ABS and PLA filament, and has a build volume of 11.2" L x 6" W x 6.1" H. It also comes equipped with a dual extrusion system to be able to print objects in two colors.

Software

A very user-friendly program to use to communicate with the Replicator 2 is MakerBot's own ReplicatorG, which can be found as a free download here: http://replicat.org/download. There are installation instructions included on that website, as additional downloads are required (Python and some drivers).

3D Modeling

Thingiverse

3D models can be uploaded and downloaded online through a free website called Thingiverse (http://www.thingiverse.com).

ReplicatorG

ReplicatorG is the main interface between the 3D model and the printer. Since 3D models are usually .cad, .obj, or .stl files, the printer cannot directly print them. ReplicatorG uses a tool called Skeinforge to take the 3D model as a .stl file, and turn it into gcode. Skeinforge slices the model into layers and determines what paths the extruder needs to take for each layer based on the parameters set in ReplicatorG. The resulting file is a .gcode file, which can be printed directly from the computer if connected via USB. To print without connecting a computer, the .gcode file needs to be converted to a .s3g file and saved to an SD card, as discussed below.

Interface

ReplicatorG will display a 3D interactive preview of the open .stl file. The column on the right offers some options on how to orient the model on the actual build platform. Some of these options include moving, rotating, or scaling the model before it is printed. It has default "snap-to" settings to center the model on the platform, and move it so that its bottom most side (the first layer) is laying just on the surface of the build platform. A model that lies below the build platform will result in an error and will not print correctly, and a model that lies above the platform will print with severe warping, since the first layer of plastic will have nothing on which to adhere.

Converting to gcode, and Print Settings

Once the model appears in the preview the way it is intended to be printed, it can be converted to gcode by either clicking on the icon at the top of the screen with an arrow and a sheet of paper with a 'g' on it, or clicking on the button on the column to the right labeled "generate gcode." A new window will pop up with settings for how the model is to be printed.

Slicing Profile: It is best to use Replicator Slicing Defaults, since the machine being used is a Replicator 2.

Extruder: Since the Replicator 2 has a dual extrusion system, either the left or the right extruder can be used.

Raft/Support: Depending on the shape and orientation of the model, a raft and/or supports might be necessary to print. Objects with flat bottoms and no overhangs do not require a raft or supports. A raft should be used for objects with a rounded, curved, or otherwise nonuniform bottom, or for an object with relatively little surface area on the bottom. The raft will add a stable, flat bed of plastic on which the printed object can adhere. If the object has overhangs, or very steep vertical curves, supports will be needed in addition to the raft. Supports are essentially pillars of plastic printed under the overhangs or curves so that the overhangs have something to rest on as they are being printed. The supports and rafts can be cut away from the final product after it has finished printing.

Post-Processing