Caution: This Dual Extruder is designed to be used as part of an existing or new 3D printer. Some adaptation is needed to make it fit any particular printer. This adaptation is up to the user. Although I provide instructions to guide the adaptation, some creativity and ingenuity will still be required of the user.
Full disclosure: I have yet to get the dual extruder mounted and fully tested on my printer. I have extruded plastic through both nozzles to verify hardware and software functionality, but printing awaits a new X Carriage design. I share it so that others can help prove and improve my design.
Print two each (It's a dual, remember?) of the Extruder Body, Tensioner, Large Gear, and Small Gear from Thingiverse. I used 40% fill. Note the support material used with the Extruder Body.
Vitamins (metal parts):
Four M4x35mm socket head bolts with nuts. (nozzles)
Four M4x16mm socket head bolts with nuts. (leveling)
Two M4x?? socket head bolts with nuts. (X Carriage mounting) Actual length needed depends on your X carriage.
Two M3x25mm socket head bolts with nuts and washers. (tensioner hinge)
Four M3x35mm socket head bolts with nuts and washers? (tensioner tightening)
Two M4x25mm socket head bolts with nuts (tensioner bearing axles)
Six M3x10mm socket head bolts (motor mounts)
Two M3x8mm or 10mm set screws with nuts. (small gear mount).
Two M4x50mm all-thread bolts with 6 nuts (three each – 2 Nylocks) and 4 washers. (main axles)
(These are hard to find. I found them in stainless with Phillips pan heads at the local hardware store. M4 threaded rod could be used; use a Nylock instead of the plain nut in the pocket on the gear.)
Two nozzles using 16mm groove mount of the same type, or at least the same length. I have used Ubis nozzles; the J-nozzle should work also. Others using 16mm groove mount may work, but are untested. A different nozzle mounting method would require modifications to the scad files.
Two NEMA14 bipolar stepper motors. The ones I use have 3.2 Ohm coil resistance.
Six 624 Bearings.
One piece of 4mmID, 5mmOD brass tubing (McMaster-Carr) long enough to be cut into two pieces the same length as filament drive gears. Details follow.
Two filament driver gears (Makerbot MK7 (SKU2394) – 5mm hole)
M3x5mm set screw (2) (filament drive gear)