Added a dual gear extruder with dual hotend capability

I took a standard $11 dual gear extruder ( right handed ). I drilled and tapped a 4mm thread for the spring screw lining up with the mounting bolt. I then purchased steel tubing 5mm od and 3mm id and cut to length for mounting the arm to the stepper.

The arm is mounted reverse making it left handed. I made plastic for the top that is a direct replacement for existing plastic. Allowing this assembly to be removed and the original to be put back on.

The rear of the stepper sits on a shelf so it is not trying to twist the plastic that it is mounted to. All of the screws have a washer to distribute the force and a lock washer so that they do not need to be over torqued.

It is nice to have a metal arm, dual hotend capability, and dual gear drive.

 

Although I am using a single hotend shroud, you could put on the original Robo shroud which holds two hotends. Looking to the right of the red arm you can see a pneumatic fitting for the second filament. I place a thread in the plastic so that you can insert any 6mm threaded fitting. On my arm I used a 6mm threaded fitting that accepts a 6mm tube, to the right of the arm I show a fitting that accepts a 4mm tube. These fitting are standard and cheap, with a quick release.

The back of the R2 has a plate that may be removed; a left handed dual gear extruder will mount directly. All you have to do is mount the extruder, connect a stepper cable then run your ptfe tube from the extruder to the fitting provided.

I have been playing with this for a month so it is all obvious to me. I should have put in more info.

I tried a bowden extruder first and did not feel I could get enough detail. So I redid everything to get dual gear direct drive on the main filament, settling for the bowden on the second filament. For me though I do not have use for a second hotend.

If you have a drill press and dremel you can modify the arm by eyeballing the hole location in the arm ( which is not critical). I used a 4mm tap but pretty much any screw will do.