Direct Drive (Gearless) Extruder

thingiverse

This direct drive extruder, employed with 3mm ABS for six months and now also used with PLA, was created by modifying the original Sells Mendel extruder. It has been split to add a spring for idler tension. The design allows printing of the entire extruder except for the hobbed bolt or MK7 gear. Two versions were made: one uses an MK7 pinch wheel, while the other employs an 8mm hobbled bolt cut and drilled for motor shaft mounting. The smaller 8mm diameter allows greater force application to the filament. It can also go faster with 1.75mm filament; the hobbed bolt design is compatible with MK7 gear drive for this use. Additionally, a 40mm fan bracket is included in the design. For assembly, drill a 4mm hole for built-in support using a 4mm drill. You'll need either a MK7 pinch wheel or an 8mm hobbed bolt (cut, drilled with a 5mm hole, and tapped across for grub screw fixation on the stepper motor shaft).