Compact Bowden Extruder with 20-20 profile fitting

thingiverse

This is a sturdy and budget-friendly lever arm extruder, designed with a simple yet effective groove bearing and flat driving gear that can handle 1.75mm filaments with ease. MaxMicron printers have some flaws in their components, but this extruder design helps to mitigate those issues by providing a solid mounting system. The original extruder design from MaxMicron is prone to bending due to inadequate motor support on the bracket. This revised design fixes that problem by offering a robust mounting solution. For flexible filament types, the drive gap is minimized, and the components are extremely strong when printed in PLA with the right orientation. If you're replacing an existing extruder, you can reuse its hardware. However, if you're building a new one, you'll need the following parts: * NEMA17 47nm stepper motor with a 5mm shaft * Flat-ground 11mm brass gear with sharp teeth for grub screws * 12mm diameter x 4mm deep 2mm groove bearing for pressure * 2x M5 x15mm bolts and tee nuts for mounting to the profile * 1x M4 x12mm bolt to mount the groove bearing * 3x M3 x20mm long mounting bolts * 1x M3 x6mm short mounting bolt * 1x Extruder spring You may be able to adapt this design to fit a Mk7 or Mk8 drive. I prefer this design because the thin 4mm groove bearing keeps it compact, and the sharp gear provides a consistent grip. Some heat is required to get the fittings to seat properly in their holes during assembly, so some care is needed. Once built, it works great. The mounting bracket is designed for the 20-20 profile of the MaxMicron printer and similar builds. It's easy to edit the SCAD file to create a bracket for a 30 or 40mm profile. Print Settings: * Printer: MaxMicron Modified * Rafts: No * Supports: Yes * Resolution: 0.25mm layers, 0.4mm tip, 0.5mm width * Infill: 40% Notes: * Print the base with no supports. * Print the arm with supports using Slic3r and pillars/0.2 detachable. * The arm must be printed in the orientation shown. * Set for 5 perimeters and 5 layers on top and bottom. * Use 40% or higher filling. * PLA is excellent and strong enough for this design. Post-Printing Assembly: 1. Attach the base to the 20-20 frame using one bolt that will be hidden once the motor is in place. 2. Fit the gear to the motor, approximately positioned on the shaft. 3. Fit the motor to the base plate using the short M3 and two long M3 bolts, and tighten until recessed. 4. Adjust the gear until it's centered around the filament hole and tighten. 5. Clear the arm slot support material, and put the groove bearing in place. 6. Hold the arm with the retaining bump in the other end of the spring, and squeeze enough to get the arm hinge bolt into place. 7. If you've attached near the top of your 20-20 frame, it's convenient to hold the extruder while hot seating the PTFE fitting. Hot Fitting: 1. Tap the 5.2mm hole for the M6 PTFE fitting using a hot M6 screw (do not heat the PFTE fitting). 2. Carefully push/twist fit a hot M4 bolt through the outer arm, through the bearing, and just to the inside edge of the through hold. 3. Slowly and with minimum heat, use a gas lighter for short bursts between pushing for a few seconds at a time. How I Designed This: I designed this extruder using OpenSCAD rules.