Raj's Minimalistic Extruder MK1 for Printrbot

thingiverse

A compact extruder design, inspired by MakerBot's Stepstruder, uses Printrbot's extruder mount but replaces six parts with only three. It can be doubled for dual nozzle printing and is paired with a Minimalistic Mk7 replacement by whosawhitsis. The design requires a NEMA 17 stepper motor, MK7 stepstruder hobbed gear, a 40mm fan, a 623-size bearing (3x10x4mm), a heavy-duty spring (~30x8mm), a hotend (16mm), and two linear bearings (8mm ID, 15mm OD). Potential issues include proper spring tension, stepper motor heat, bearing alignment, binding of the bearing on the plastic arm, extruder overheating due to close nozzle proximity, and maintaining print speed. The author added foil tape behind the hot end as a precautionary measure and used five smaller springs stacked together with an M4 screw for quick filament change. This design performs well at 100mm/min and can handle up to two-hour prints without overheating issues.