this is a proof of concept in the use of driving more than 2 filaments (3 here) using 2 motors. one motor drives the filament while the other drives a cam that pushes the filament into the drive shaft.
i am currently preparing to test this, but wanted to get it out there. current issues are that is does not have good access to the drive mechanism for cleaning or feeding filament and that much of it was designed to be machined instead of printed. the side plates are to big for a cupcake, but i ws able to print a few of the pieces on one. it may also not be compatible with other motors until there is a redesign, as the motors are integral to its strength.
if anyone has improvements, let me know.
EDIT: added an IGES assembly file(let me know when you find its broken, and how to fix it) and SW2005 part and assembly files. also added an exploded image
EDIT: lookes like this has been worked on a bit already by wildseyed http://www.thingiverse.com/thing:10783 . not sure if i should list it as derivative.
Finally got more than 1 hot end functional at a time, so to check out the filament drive in action see http://youtu.be/CVaYHlLkvWM
it works! all 3 filaments running:
mill (or print) the side plates, machine the drive shaft and camshaft, print the infeed and top plates.
i am using:
2 - 32 pitch gears of 19 and 54 teeth.
4 - 5x13x3mm bearings for the drive and cam shafts.
3 - 608 bearings for idlers.
4mm teflon tubing.
3 - 4mm x 1/8 pipe push-lock fittings.