With all 4 extruders, the platter, and the Z axis, the machine requires 10 independently controlled motor axes. No current 3D printer controller is capable of driving more than 5 stepper motors at once. While researching options to overcome this limitation we discovered a project called Decapede , which aims to sell a 3D printer / CNC controller that can drive 10 motors (thus the name). The Decapede can also drive 8 heaters and read from 8 thermal sensors. The processor is an Arduino Mega 2560. More information can be found at http://printm3d.com/portfolio-item/decapede/ or http://reprap.org/wiki/Decapede.

We got in contact with the developers early on, who incorporated our feedback into the design and offered to let us test a prototype. Unfortunately, as time went on it became evident that the Decapede would not be read in time to complete the senior design project. Currently, several prototypes have been produced and various bugs have been discovered in the design. Once the issues are resolved, the developers plan to launch a crowdfunding campaign to fund production.

Our fallback plan was to use a standard 3D printer controller, the RepRap Arduino Mega Polulu Shield (RAMPS) version 1.4 (http://reprap.org/wiki/RAMPS). RAMPS can drive 5 motors and 3 heaters. This means that we would be unable to run all 4 extruders. By splicing the motor connections we were able to run two axes in parallel, thus allowing us to drive two extruders with the standard RAMPS controller.

A standard ATX computer power supply was chosen for several reasons. First, they can provide the high power necessary to run the machine. Secondly, they are cheap and readily available. They also meet the 12 Volt requirement of our electronics. Modern switching power supplies are also very efficient and provide clean output.

In order to select the appropriate power supply we first had to determine the power requirements of the machine. The following chart shows a breakdown of each component and it’s peak wattage. We expect each component to draw less power under normal operation. Also, although we have a 240 Watt heated bed, it will only draw 120 Watts since it will only be operating at 12 Volts as opposed to 24.

Our selected power supply is a Thermaltake Toughpower 750W purchased from Newegg for $70. In order to convince the power supply to operate outside of a personal computer, we had to ground the PS_ON line. This was done by connecting a paperclip between the green wire and a black wire.Another important consideration is that not all power supplies are capable of delivering their maximum wattage on the 12 Volt line. We verified that our chosen power supply would deliver 720 Watts at 12 Volts.