This project is an upgrade for a low-cost Prusa i3 clone ($150 on ebay) to use a pair of bowden E3D V6 print heads.
Step 1: Component Overview
The upgrade components are designed to make the most of the existing parts and allow upgrades if wanted. The motor bracket allows the extruder that formerly was located in the carriage to be hung off the top of the machine frame. With the bowden tube exiting forward horizontal down to the print head.
The core part which holds the two extruder heads and funnels the cooling air over their fins (TFB0412EHN or other 40x40 fan). And the supporting metal carriage needs modifying (trimming/filing; hand file, hand drill and dremmel meta cuttoff discs would be best tools) to allow the V6 heads to pass through it. By placing the base part in the carriage the required circular holes can be marked out.
Step 2: Print Out the Components
The complete model in STEP format is included here along with the separate components in STL format for direct printing using the un-modified printer.
Step 3: Update Melzi Controller Board
This clone uses a melzi derived control board, the pinout for this. I'm using repetier with a raspberry pi as the print server and the LCD control button thing removed. The configuration file for use as a base when using the repetier firmware configurator tool.
When compiling (needs arduino IDE) the Melzi board is the same as a "Sanguino". when paired with arduino ide 1.6.8, to add sanguino board to the board list, go to File>Preference>Additional Boards Manager URLs, add the link below