I wasn't sure whether to post this in here or on the open source hardware board. Since I am building a 3-D printer from mostly from scratch... again... I have been thinking about extruders. The main problem that I am partaking in challenging is the multi-color extruder. The design I have in mind would have 4+ colors attached to one main motor, but activated by small servos.


My thoughts on this would be to one high torque motor that drives to main gears with the filaments attached to swing arms that engage/disengage based on program. The other option would be to use two motors in sync with same everything. I already do this with my Z-axis for even lift, so synchronizing this shouldn't pose a problem. Only software for the servos would add a few lines of code, and it looks like a copypasta job to accomplish all of this. The only potential problem that I have been wrangling with is I need a default subsurface color, and I need white and black to be colors of their own to make CMYKW. Unlike 2-d you don't have the advantage of your medium coming precolored white. You also need a default color to take up a considerable amount of the volume so you're not wasting all of your color through the entire structure. This issue of color and motor strength to power the colors are the simple problem.
The main problems are shape and make of the extruder nozzle, and how the mixture will be done in the extruder so you only get the color that you want. I believe the mixture can be controlled in software, but extensive testing will have to be accomplished. With this being on my number 2 in my project list I am hoping for some ideas from veteran 3d printer enthusiasts. Just to give you a heads up on what I am working on.. I am rebuilding my printer which is composed of wood, tube, and cold rolled steel. I won't be able to touch any printing methods tell I finish rebuilding my printer. My print bed only moves along the z-axis... and I am not using any standard measurements for anything. My axis are powered by something by something inch threaded rod 14 turns per inch, and I mainly print PLA for anything. So this project will have to be adjusted to my custom settings in firmware, and
All abs printing is out of the equation as of right now.Tell me what you think, and I would love some pointers on what you think I should do to move forward now that I have a cut from dirt rough idea.