D-bot MMU

thingiverse

This is a high-tech upgrade for the C/D-bot and related printers, using the cutting-edge Prusa MK2/S Multi-Material Upgrade (MMU) kit. Required components: * Prusa MK2/S MMU kit * 4 x 600mm PTFE tubes * M3 and M5 hardware * Dupont crimp, pins & headers Optional components: * BL Touch * Drag chain * 40mm fan adapter for hotend The Prusa MMU kit parts are open-source, but the retail cost of the 4 x Bondtech gears is almost as much as the whole kit. Custom metal cooling tubes and other kit parts can be difficult to source. Firmware: A modified Marlin 1.1.6 firmware is included. Although 1.1.6 supposedly supports the motor switch board, I made some necessary changes to get it working. Note: You will likely need to edit the Configuration.h file, especially if you use a different size bed or don't use the BL Touch. Electronics: The motor switch board takes a 4-pin connection from the RAMPS board and outputs to 4 stepper connectors. When connecting steppers, keep in mind that the 2nd and 4th stepper cables must be reversed due to the motor/idler being reversed compared to the 1st and 3rd. Loading & unloading filament: Unlike a Prusa printer, this Marlin firmware does not have built-in LCD options for loading & unloading filament. You can do this using software like Pronterface or Octoprint. To load filament, push it into the extruder until it just enters the gears, then send a command to extrude 660mm of filament so that it stops in the middle of the metal tube. Note: If you have "prevent cold extrusion" enabled, you need to either heat the hotend to print temp or send M302 P1 first. To unload filament, first send Tn command (where n is 0-3), then "print" the unload gcode attached here. This does a special ramming & tip forming procedure to ensure the filament is loaded and shaped correctly for the next print. Printing: Use Slic3r multi-material edition or KISS slicer with the Prusa MK2 MMU print settings. I increased retraction to 6.5mm due to the longer Bowden tubes compared to the Prusa MK2. You can probably increase speed quite a bit later, but it's best to start slow until you get the feel of things.