I just uploaded a few bowden extruder designs that I’ve been testing. They are all dual drive, direct drive, print in a single piece, and none of them have a quick release mechanism for the filament (I usually load and unload filament using gcode scripts).
The extruders will behave similarly, they all should provide plenty of extrusion force given a large enough motor, but the parts, form factor and cost differ. See my Calibrating Extruder Grip post for info on configuring a new extruder. Here’s some notes on the differences between the extruders:
Gearstruder J7
- Uses one NEMA17 motor
- Uses Printrbot Gearhead drive gears
- Configurable fixed gap
Pros
- Compact
- Gears never need cleaning
Cons
- Drive gears are about $25
Gearstruder J4
- Uses one NEMA14 motor (preferably a large one)
- Uses Printrbot Gearhead drive gears
- Configurable fixed gap
Pros
- Small
- Gears never need cleaning
Cons
- May not have enough torque for use with smaller nozzle diameters
- Drive gears are about $25
Fostruder K4
- Uses two NEMA14 motors
- Uses knurled drive gears
- Uses a M5 brass insert and a M5 threaded bowden coupler
- Configurable gap or tension
Pros:
- More compact than the Fostruder H4
- Easy to install, knurled gears don’t need to be aligned
Cons:
- Slightly lower resolution than the Fostruder H
- Requires two motors (in series or parallel)
- Knurled gears deform the filament
Fostruder H4
- Uses two NEMA14 motors
- Uses hobbed drive gears
- Configurable gap or tension
Pros
- Slightly better resolution than the Fostruder K
Cons
- Slightly larger than the Fostruder K4
- Hobbed drive gears may need cleaning if they fill with filament
- Requires two motors (in series or parallel)
Quadstruder K7
- Uses a NEMA17 Motor
- Uses 4 drive gears, two as gears, two knurled gears for the filament
- Uses a 5mm dowel pin and bearings
Pros:
- Cheap and effective
Cons:
- lots of parts
- Knurled gears deform the filament
- Brass gears wear over time
Quadstruder K7 v2
- Uses a NEMA17 Motor
- Uses stainless steel gears to drive both knurled gears
- Uses a 5mm dowel pin and bearings
Pros:
- Cheap and effective
Cons:
- lots of parts
- Knurled gears deform the filament
All of my extruder designs can be found in this collection.