Powder Deposition Print Head

January 2011 - August 2011

University of Washington


Hopper prototype design.

Current Power Printers
Current 3D powder printers work by spreading a full layer of build material, then selectively applying binder to areas until the layer shape is formed. This process is repeated, eventually producing an object. Full color models can be built through changing the binder color.

The Project


Feed plate model.
Powder deposition, is closer to FDM technology. It prints the layer and necessary supports directly into the desired shape. The motivation behind the development of this printing method is the expansion of 3D printing to handle multiple materials or colors in a single build. For single material printing, the powder that is not part of the final object is reusable. However, this becomes a wasteful process when using multiple materials as even the unused powder would mix together.

Powder deposition attempts to minimize waste by limiting the unused powder that is placed on the build platform to support material. The current iteration of the print head can use two different build materials, and the concentration of each powder at a given point is controlled by pulse width modulation. A large scale version has been installed on Big Red, a former plasma cutter that has been turned into a 3D printer.

The powder is deposited through the use of vibrating motors which loosen the powder from individual nozzles. Since it was desired to control multiple powders and vary the concentrations of each, a feed plate like the one seen on the right was developed. By rotating the plate, the number of holes would vary and restrict the volume of powder released.

The feed plate is rotated by a stepper motor, which moves according to instructions from a data file. The data file contains a series of numbers from 0 to 15, each one assigned to a particular cluster of holes. An Arduino reads the data file and drives the stepper motor until it reaches the appropriate orientation.


Hardware.
The data file could be generated from 4-bit grayscale image through the use of a program written for the open-source environment Processing. In use, the image would be the shape of the current build layer. Throught Processing, a g-code file was also output to direct the carriage's x and y movements.

The print head was my senior design project at the University of Washington. I worked as a part of a team to develop a large-scale 3D printer from January to June of 2011. Reports about my work can be found below in the Documentation section.

Documentation
Winter 2011 |Exploration of Multi-Material Additive Manufacturing|
Spring 2011 |Development of a Multi-Material Powder Print Head|
Summer 2011 |Multi-Material Powder Print Head Project Update|

Code
Processing |Preprocessor for a 4-bit grayscale image|
Arduino |Firmware|

Model Files
Motor Offset |link|
Big Red Hopper |link|