I like my 3D printer, but there are a lot of things I’ve decided I want to change about it since I built it a couple of years ago. One of the things I want to change is the style of extruder I’m using. I’m currently using a Wade’s style extruder, they’re kind of large and have big external gearing on them, they look cool while running, but it doesn’t have a ‘clean’ look to it, in my opinion.

I decided to used a stepper motor with a built in planetary gear drive and get rid of the big external gear set. Additionally I wanted to house the motor as I don’t like the look of bare motors in finished equipment, and I eventually want a printer that is a finished piece of equipment.

I searched around for designs I would like, and found a couple. The one I really liked was for 1.75mm filament only, and had no source files so I could modify it to 3mm(2.85).  Here’s a link to the one I liked, made by Thingiverse user robkar. You’ll see my extruder looks like a pretty close copy, with some minor changes, and I really like how it looks.

I drew it up in Autodesk Fusion 360, this was really my first Fusion 360 project and I’m pretty happy with it. I look forward to using the CAM features to build some jobs for my CNC router as well.

Below is the extruder block and arm, since the hot end is actually separated from the filament drive section by a Bowden tube, it’s probably better to call this the filament drive.

Filament Drive

This is the motor housing, unlike the original design of this extruder I made the motor housing a single box with an end cap, vs two motor housings and an end cap.


Motor Housing


The design printed out pretty easy. I use an e3D-v4 hotend with a .4mm nozzle @ .15mm layer height and translucent blue PLA, with some hardware added it has a super tight grip on the filament and should do well.  I need to pick up another motor and drive gear, and then I will make a mirrored version for the second extruder.

New Filament Drive


I still want to make some changes to this design:

  • The arm compresses the filament against the hobbed drive with one 4mm bolt, and because it has to be below the hole at the midpoint which the filament goes through it causes an uneven pull on the extruder arm, warping it slightly. While it doesn’t seem to affect the performance of the filament drive at the moment I think I am going to redesign the block and the arm to have a second bolt above the filament, this should evenly distribute the load in the arm.  The other option would be to machine it in aluminum and then I could get away with one bolt.
  • I need some way to mount the filament drives to an extrusion. I could add tabs to the motor case itself, or design a compression clamp of some sort which holds the motor housing in place.
  • Additional cooling may need to be considered. My existing extrusion motor doesn’t get very hot, so I’m not too worried about it, but enclosed spaces can drastically change thermal buildup over long operational times.  I’ve added a few vents to the sides, and the motors for the new printer will be installed within an airflow channel in the printer.

More details as they come. I’m researching ideas for the printer frame, I’m thinking of a freestanding, rigid and enclosed design. I also want to achieve high speeds at low layer heights and have at least 2 material extrusion. I’m not worried about multiple colors, but alternate support materials or printing flexible materials into nylon materials and things along those lines would be cool, I think.


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