The basic idea behind this extruder is a quick-release mechanism that is operated by turning the knob at the side. Turning it clockwise by 120° will release the filament permanently. Turning it backwards by 120° will re-lock the filament. Further it includes a gear drive with a ration of 3:1. The extruder is symmetrical, so you can position it however you want. Just switch the bowden tube adapter between top and bottom.
The dimensions in this part are set exactly without taking in account that 3D-printers usally produce smaller holes, i.e. for the 625ZZ bearing the hole is exactly 16 mm. If you print it like this most of the parts are probably to tight. The way I like to do this is to use the horizontal-expansion function of the slicer (that how it is named in cura, the naming in other slicers might differ). For my printer a horizontal-expansion of -0.15 mm gives a nice tight fit without manual post processing. For your printer you might need slightly different setting. Try to find them, it's makes designing stuff much easier and the designs are less printer dependet.
After assembly with the instructions in the images above make sure that the knob is screwed on only very lightly and first set your desired tension with the two screws on the side of the extruder (if you use fixed tension you can obviously skip the last part). After that turn the knob and "click" it over several times until it is just slightly lose in the in the filament-tensioned-position and quite tight in the filament-free-position. You will see what I mean when you play around with it. If you over-tightened the knob, so that it is not loose in the initial position anymore, pull it outwards and turn it back.
- 2 x 625ZZ bearing
- 1 x 623ZZ bearing
- 1 x filament drive gear (MK8 or compatible)
- 1 x NEMA17 stepper
- 1 x spring (~ 8x20 mm)
- 4 x M3 threaded inserts (4x5 mm) (additional inserts for mounting)
- 4 x M3 nuts
- 7 x M3x6 mm screws
- 7 x M3x20 mm screws
- 1 x M3x10 mm screw
- 1 x M3x30 mm screw
- 1 x M5x60 mm screw
- 2 x M5 washer
- 1 x M5 nut
- 1 x Bowden tube adapter (E3D mount)